Sildenafil citrate therapy for severe early-onset intrauterine growth restriction

Maternal tadalafil treatment does not increase uterine artery blood flow or oxygen delivery in the pregnant ewe

Increasing placental perfusion (PP) could improve outcomes of growth-restricted fetuses. One way of increasing PP may be by using phosphodiesterase (PDE)-5 inhibitors, which induce vasodilatation of vascular beds. We used a combination of clinically relevant magnetic resonance imaging (MRI) techniques to characterize the impact that tadalafil infusion has on maternal, placental and fetal circulations. At 116-117 days' gestational age (dGA; term, 150 days), pregnant ewes (n = 6) underwent fetal catheterization surgery. At 120-123 dGA ewes were anaesthetized and MRI scans were performed during three acquisition windows: a basal state and then ∼15-75 min (TAD 1) and ∼75-135 min (TAD 2) post maternal administration (24 mg; intravenous bolus) of tadalafil. Phase contrast MRI and T2 oximetry were used to measure blood flow and oxygen delivery. Placental diffusion and PP were assessed using the Diffusion-Relaxation Combined Imaging for Detailed Placental Evaluation-'DECIDE' technique. Uterine artery (UtA) blood flow when normalized to maternal left ventricular cardiac output (LVCO) was reduced in both TAD periods. DECIDE imaging found no impact of tadalafil on placental diffusivity or fetoplacental blood volume fraction. Maternal-placental blood volume fraction was increased in the TAD 2 period. FetalD O 2 ${D_{{{\mathrm{O}}_2}}}$ andV ̇ O 2 ${\dot V_{{{\mathrm{O}}_2}}}$ were not affected by maternal tadalafil administration. Maternal tadalafil administration did not increase UtA blood flow and thus may not be an effective vasodilator at the level of the UtAs. The increased maternal-placental blood volume fraction may indicate local vasodilatation of the maternal intervillous space, which may have compensated for the reduced proportion of UtAD O 2 ${D_{{{\mathrm{O}}_2}}}$ .

Tadalafil for Treatment of Fetal Growth Restriction: A Review of Experimental and Clinical Studies

Fetal growth restriction (FGR) is a major concern in perinatal care. Various medications have been proposed as potential treatments for this serious condition. Nonetheless, there is still no definitive treatment. We studied tadalafil, a phosphodiesterase-5 inhibitor, as a therapeutic agent for FGR in clinical studies and animal experiments. In this review, we summarize our preclinical and clinical data on the use of tadalafil for FGR. Our studies in mouse models indicated that tadalafil improved FGR and hypertensive disorders of pregnancy. A phase II trial we conducted provided evidence supporting the efficacy of tadalafil in prolonging pregnancy (52.4 vs. 36.8 days; p = 0.03) and indicated a good safety profile for fetuses and neonates. Fetal, neonatal, and infant mortality was significantly lower in mothers receiving tadalafil treatment than that in controls (total number: 1 vs. 7, respectively; p = 0.03), and no severe adverse maternal events associated with tadalafil were observed. Although further studies are needed to establish the usefulness of tadalafil in FGR treatment, our research indicates that the use of tadalafil in FGR treatment may be a paradigm shift in perinatal care.

Childhood outcomes after maternal antenatal sildenafil treatment for severe early-onset fetal growth restriction: a randomized trial (STRIDER NZAus)

In this follow-up at 2.5 years of children from the STRIDER NZAus Trial (N = 112), in which women with singleton pregnancies affected by severe early fetal growth restriction were randomized to sildenafil citrate 75 mg daily or placebo until 32 weeks, there was no difference between groups in survival without neurosensory impairment, defined as any of cerebral palsy, deafness, blindness, cognitive delay (Bayley III cognition or language score >1 SD below mean) or motor delay: 30/56[54%] vs. 34/56[61%]; aOR = 0.74, 95%CI: 0.31, 1.77. However, children exposed to sildenafil appeared to be more likely to have cognitive delay (13/45[29%] vs. 4/40[10%]; aOR = 3.71, 95% CI: 1.01, 13.63) but less likely to have emotional-behavioural difficulties (2/43[5%] vs. 8/38[21%]; aOR = 0.19, 95%CI: 0.03, 1.00). Conclusion: maternal sildenafil treatment for severe early-onset FGR was not associated with altered survival free of neurosensory impairment at 2.5 years' corrected age.

Interventions affecting the nitric oxide pathway versus placebo or no therapy for fetal growth restriction in pregnancy

BACKGROUND

Fetal growth restriction (FGR) is a condition of poor growth of the fetus in utero. One of the causes of FGR is placental insufficiency. Severe early-onset FGR at < 32 weeks of gestation occurs in an estimated 0.4% of pregnancies. This extreme phenotype is associated with a high risk of fetal death, neonatal mortality, and neonatal morbidity. Currently, there is no causal treatment, and management is focused on indicated preterm birth to prevent fetal death. Interest has risen in interventions that aim to improve placental function by administration of pharmacological agents affecting the nitric oxide pathway causing vasodilatation.

OBJECTIVES

The objective of this systematic review and aggregate data meta-analysis is to assess the beneficial and harmful effects of interventions affecting the nitric oxide pathway compared with placebo, no therapy, or different drugs affecting this pathway against each other, in pregnant women with severe early-onset FGR.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (16 July 2022), and reference lists of retrieved studies.

SELECTION CRITERIA

We considered all randomised controlled comparisons of interventions affecting the nitric oxide pathway compared with placebo, no therapy, or another drug affecting this pathway in pregnant women with severe early-onset FGR of placental origin, for inclusion in this review.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane Pregnancy and Childbirth methods for data collection and analysis.

MAIN RESULTS

We included a total of eight studies (679 women) in this review, all of which contributed to the data and analysis. The identified studies report on five different comparisons: sildenafil compared with placebo or no therapy, tadalafil compared with placebo or no therapy, L-arginine compared with placebo or no therapy, nitroglycerin compared with placebo or no therapy and sildenafil compared with nitroglycerin. The risk of bias of included studies was judged as low or unclear. In two studies the intervention was not blinded. The certainty of evidence for our primary outcomes was judged as moderate for the intervention sildenafil and low for tadalafil and nitroglycerine (due to low number of participants and low number of events). For the intervention L-arginine, our primary outcomes were not reported. Sildenafil citrate compared to placebo or no therapy (5 studies, 516 women) Five studies (Canada, Australia and New Zealand, the Netherlands, the UK and Brazil) involving 516 pregnant women with FGR were included. We assessed the certainty of the evidence as moderate. Compared with placebo or no therapy, sildenafil probably has little or no effect on all-cause mortality (risk ratio (RR) 1.01, 95% confidence interval (CI) 0.80 to 1.27, 5 studies, 516 women); may reduce fetal mortality (RR 0.82, 95% CI 0.60 to 1.12, 5 studies, 516 women), and increase neonatal mortality (RR 1.45, 95% CI 0.90 to 2.33, 5 studies, 397 women), although the results are uncertain for fetal and neonatal mortality as 95% confidence intervals are wide crossing the line of no effect. Tadalafil compared with placebo or no therapy (1 study, 87 women) One study (Japan) involving 87 pregnant women with FGR was included. We assessed the certainty of the evidence as low. Compared with placebo or no therapy, tadalafil may have little or no effect on all-cause mortality (risk ratio 0.20, 95% CI 0.02 to 1.60, one study, 87 women); fetal mortality (RR 0.11, 95% CI 0.01 to 1.96, one study, 87 women); and neonatal mortality (RR 0.89, 95% CI 0.06 to 13.70, one study, 83 women). L-Arginine compared with placebo or no therapy (1 study, 43 women) One study (France) involving 43 pregnant women with FGR was included. This study did not assess our primary outcomes. Nitroglycerin compared to placebo or no therapy (1 studies, 23 women) One study (Brazil) involving 23 pregnant women with FGR was included. We assessed the certainty of the evidence as low. The effect on the primary outcomes is not estimable due to no events in women participating in both groups. Sildenafil citrate compared to nitroglycerin (1 study, 23 women) One study (Brazil) involving 23 pregnant women with FGR was included. We assessed the certainty of the evidence as low. The effect on the primary outcomes is not estimable due to no events in women participating in both groups.

AUTHORS' CONCLUSIONS

Interventions affecting the nitric oxide pathway probably do not seem to influence all-cause (fetal and neonatal) mortality in pregnant women carrying a baby with FGR, although more evidence is needed. The certainty of this evidence is moderate for sildenafil and low for tadalafil and nitroglycerin. For sildenafil a fair amount of data are available from randomised clinical trials, but with low numbers of participants. Therefore, the certainty of evidence is moderate. For the other interventions investigated in this review there are insufficient data, meaning we do not know whether these interventions improve perinatal and maternal outcomes in pregnant women with FGR.

The effects of sildenafil citrate on intrauterine growth restriction: a systematic review and meta-analysis

BACKGROUND

An increase in vascular resistance of uterine vessels is associated with intrauterine growth restriction (IUGR). Sildenafil citrate, a phosphodiesterase-5 inhibitor that stabilizes cyclic guanosine monophosphate (cGMP) and increases nitric oxide levels, improves placental perfusion by dilation of spiral arteries and is beneficial in managing IUGR. This study aims to determine the effectiveness of sildenafil citrate in improving perinatal outcomes in IUGR pregnancies.

METHODS

Meta-analysis was performed on data extracted from all studies specific to sildenafil citrate in IUGR management, searching relevant articles on PubMed, Medline, Google Scholar, Embase, and Cochrane databases. Publications identified by the manual search, based on references in reviews, were also included. Dichotomous results were presented as risk ratio (95% confidence interval), while continuous results were expressed as mean difference (MD); samples represented by the random effects model.

RESULTS

Nine trials were included where the sildenafil citrate effect was compared with a placebo or no intervention. A significant increase in birth weight [SMD (95% CI), 0.69 (0.31, 1.07)] was seen in IUGR pregnancies managed with sildenafil. However, gestational age (SMD (95% CI), 0.44 (-0.05, 0.94], fetal death rate [RR (95% CI), 0.56 (0.17, 1.79)] in IUGR pregnancies was not changed by sildenafil. Neonatal death [RR (95% CI), 0.93 (0.47, 1.86)] and neonatal intensive care unit (NICU) admissions [RR (95% CI), 0.76 (0.50, 1.17)] were not significantly different between sildenafil and control groups.

CONCLUSION

Sildenafil citrate increases birth weight and prolonged pregnancies but did not affect stillbirth rate, neonatal death, and NICU admission.

TRIAL REGISTRATION

The study was registered in PROSPERO on September 18, 2021 (CRD42021271992).

Early Onset Intrauterine Growth Restriction-Data from a Tertiary Care Center in a Middle-Income Country

Background and Objectives: In this study, we aimed to describe the clinical and ultrasound (US) features and the outcome in a group of patients suspected of or diagnosed with early onset intrauterine growth restriction (IUGR) requiring iatrogenic delivery before 32 weeks, having no structural or genetic fetal anomalies, managed in our unit. A secondary aim was to report the incidence of the condition in the population cared for in our hospital, data on immediate postnatal follow-up in these cases and to highlight the differences required in prenatal and postnatal care. Materials and Methods: We used as single criteria for defining the suspicion of early IUGR the sonographic estimation of fetal weight < p10 using the Hadlock 4 technique at any scan performed before 32 weeks’ gestation (WG). We used a cohort of patients having a normal evolution in pregnancy and uneventful vaginal births as controls. Data on pregnancy ultrasound, characteristics and neonatal outcomes were collected and analyzed. We hypothesized that the gestational age (GA) at delivery is related to the severity of the condition. Therefore, we performed a subanalysis in two subgroups, which were divided based on the GA at iatrogenic delivery (between 27+0 WG and 29+6 WG and 30+0−32+0 WG, respectively). Results: The prospective cohort study included 36 pregnancies. We had three cases of intrauterine fetal death (8.3%). The incidence was 1.98% in our population. We confirmed that severe cases (very early diagnosed and delivered) were associated with a higher number of prenatal visits and higher uterine arteries (UtA) pulsatility index (PI) centile in the third trimester—TT (compared with the early diagnosed and delivered). In the very early suspected IUGR subgroup, the newborns required significantly more NICU days and total hospitalization days. Conclusions: Patients with isolated very early and early IUGR—defined as ultrasound (US) estimation of fetal weight < p10 using the Hadlock 4 technique requiring iatrogenic delivery before 32 weeks’ gestation—require closer care prenatally and postnatally. These patients represent an economical burden for the health system, needing significantly longer hospitalization intervals, GA at birth and UtA PI centiles being related to it.

A review of ex vivo placental perfusion models: an underutilized but promising method to study maternal-fetal interactions

Studying the placenta can provide information about the mechanistic pathways of pregnancy disease. However, analyzing placental tissues and manipulating placental function in real-time during pregnancy is not feasible. The ex vivo placental perfusion model allows observing important aspects of the physiology and pathology of the placenta, while maintaining its viability and functional integrity, and without causing harm to mother or fetus. In this review, we describe and compare setups for this technically complex model and summarize outcomes from various published studies. We hope that our review will encourage wider use of ex vivo placental perfusion, which in turn would generate more knowledge to improve pregnancy outcomes.

Sildenafil during the 2nd and 3rd Trimester of Pregnancy: Trials and Tribulations

Sildenafil, a phosphodiesterase 5 inhibitor with a vasodilatory and anti-remodeling effect, has been investigated concerning various conditions during pregnancy. Per indication, we herein review the rationale and the most relevant experimental and clinical studies, including systematic reviews and meta-analyses, when available. Indications for using sildenafil during the second and third trimester of pregnancy include maternal pulmonary hypertension, preeclampsia, preterm labor, fetal growth restriction, oligohydramnios, fetal distress, and congenital diaphragmatic hernia. For most indications, the rationale for administering prenatal sildenafil is based on limited, equivocal data from in vitro studies and rodent disease models. Clinical studies report mild maternal side effects and suggest good fetal tolerance and safety depending on the underlying pathology.

Halting the Canadian STRIDER randomised controlled trial of sildenafil for severe, early-onset fetal growth restriction: ethical, methodological, and pragmatic considerations

Objectives

To determine the efficacy and safety of sildenafil citrate to improve outcomes in pregnancies complicated by early-onset, dismal prognosis, fetal growth restriction (FGR). Eligibility: women ≥ 18 years, singleton, 18 + 0–27 + 6 weeks’ gestation, estimated fetal weight < 700 g, low PLFG, and ≥ 1 of (i) abdominal circumference < 10th percentile for gestational age (GA); or (ii) reduced growth velocity and either abnormal uterine artery Doppler or prior early-onset FGR with adverse outcome. Ineligibility criteria included: planned termination or reversed umbilical artery end-diastolic flow. Eligibility confirmed by placental growth factor (PlGF) < 5 th percentile for GA measured post randomization. Women randomly received (1:1) either sildenafil 25 mg three times daily or matched placebo until either delivery or 31 + 6 weeks. Primary outcome: delivery GA. The trial stopped early when Dutch STRIDER signalled potential harm; despite distinct eligibility criteria and IRB and DSMB support to continue, because of futility. NCT02442492 [registered 13/05/2015].

Results

Between May 2017 and June 2018, 21 (90 planned) women were randomised [10 sildenafil; 11 placebo (1 withdrawal)]. Baseline characteristics, PlGF levels, maternal and perinatal outcomes, and adverse events did not differ. Delivery GA: 26 + 6 weeks (sildenafil) vs 29 + 2 weeks (placebo); p = 0.200. Data will contribute to an individual participant data meta-analysis.

Pregnancy in Congenital Heart Disease, Complicated by Pulmonary Arterial Hypertension—A Challenging Issue for the Pregnant Woman, the Foetus, and Healthcare Professionals

Background and Objectives: Pregnancy and delivery in patients with congenital heart disease (CHD) and pulmonary arterial hypertension (PAH) carry a very high risk for maternal and foetal complications and are contraindicated according to the guidelines. In the last decades, when an available modern PAH-targeted medication therapy and a new management concept improved patients’ well-being and survival, some PAH-CHD females decided to conceive. Of note, despite advanced treatment and modern healthcare system possibilities, dealing with pregnancy in a diverse PAH-CHD population is still challenging. The study aimed to share our experience with PAH-CHD pregnancies and discuss the risk assessment and current management of these patients with the combination of two rare diseases. Materials and Methods: The retrospective search of pulmonary hypertension and adult CHD registries in our hospital was performed, selecting all patients with CHD and PAH who conceived pregnancy from 2013 to 2021. Baseline demographic, clinical, and functional characteristics and clinical outcomes were collected. Results: Thirteen pregnancies in eight patients with PAH-CHD resulted in seven live births, three miscarriages, and three terminations. Five women were diagnosed with Eisenmenger syndrome (ES) and three with residual PAH after CHD repair. Before pregnancy, half of them were in WHO functional class III. Seven (87.5%) patients received targeted PAH treatment with sildenafil during pregnancy. In addition, the two most severe cases were administered with iloprost during peripartum. Three ES patients delivered preterm by Caesarean section under general anaesthesia. No neonatal mortality was reported. Maternal complications were observed in half of our cases. One patient died 12 days after the delivery in another hospital due to deterioration of heart failure. Conclusions: On the basis of our clinical experience, we conclude that pregnancy and delivery carry a high risk for maternal complications and should be avoided in women with PAH-CHD. The individualised approach of multidisciplinary care and appropriate monitoring are mandatory in reducing the risk of adverse outcomes.

Pharmacokinetics and pharmacodynamics of sildenafil in fetal lambs on extracorporeal support

BACKGROUND

Maternal transplacental administration of sildenafil is being considered for a variety of fetal conditions. Clinical translation also requires evaluation of fetal safety in a higher species, such as the fetal lamb. Experiments with the pregnant ewe are curtailed by minimal transplacental transfer as well as limited access to the fetus. The EXTra-uterine Environment for Neonatal Development (EXTEND) model renders the isolated fetal lamb readily accessible and allows for direct fetal administration of sildenafil.

METHODS

Five fetal lambs were placed on extracorporeal support in the EXTEND device and received continuous intravenous (IV) sildenafil (0.3-0.5-0.7 mg/kg/24hr) for a duration of one to seven days. Plasma sildenafil concentrations were sampled at regular intervals to establish the pharmacokinetic profile using population pharmacokinetic modeling. Serial Doppler ultrasound examination, continuous non-invasive hemodynamic monitoring and blood gas analysis were done to evaluate the pharmacodynamic effects and fetal response.

FINDINGS

The target concentration range (47-500 ng/mL) was attained with all doses. Sildenafil induced an immediate and temporary reduction of pulmonary vascular resistance, mean arterial pressure and circuit flow, without change in fetal lactate levels and acid-base status. The duration of the systemic effects increased with the dose.

INTERPRETATION

Immediate temporary pulmonary vascular and systemic hemodynamic changes induced by sildenafil were biochemically well tolerated by fetal lambs on extracorporeal support, with the 0.5 mg/kg/24 h dose balancing rapid attainment of target concentrations with short-lived systemic effects.

RESEARCH IN CONTEXT

None.

SEARCH STRATEGY BEFORE UNDERTAKING THE STUDY

A literature review was conducted searching online databases (Medline, Embase and Cochrane), using search terms: fetal OR prenatal OR antenatal AND sildenafil, without time-limit and excluding human studies. Where relevant, investigators were contacted in order to avoid duplication of work.

EVIDENCE BEFORE THIS STUDY

Prenatal therapy with sildenafil, a phosphodiesterase-5 inhibitor with vasodilatory and anti-remodeling effects on vascular smooth muscle cells, has been considered for a variety of fetal conditions. One multicenter clinical trial investigating the benefit of sildenafil in severe intrauterine growth restriction (the STRIDER-trial) was halted early due to excess mortality in the sildenafil-exposed arm at one treatment site. Such findings demonstrate the importance of extensive preclinical safety assessment in relevant animal models. Transplacentally administered sildenafil leads to decreased pulmonary arterial muscularization, preventing or reducing the occurrence of pulmonary hypertension in rat and rabbit fetuses with diaphragmatic hernia (DH). Validation of these results in a higher and relevant animal model, e.g. fetal lambs, is the next step to advance clinical translation. We recently demonstrated that, in contrast to humans, transplacental transfer of sildenafil in sheep is minimal, precluding the in vivo study of fetal effects at target concentrations using the conventional pregnant ewe model.

ADDED VALUE OF THIS STUDY

We therefore used the extracorporeal support model for fetal lambs, referred to as the EXTra-uterine Environment for Neonatal Development (EXTEND) system, bypassing placental and maternal metabolism, to investigate at what dose the target concentrations are reached, and what the fetal hemodynamic impact and response are. Fetal hemodynamic and metabolic tolerance to sildenafil are a crucial missing element on the road to clinical translation. This is therefore the first study investigating the pharmacokinetics, hemodynamic and biochemical effects of clinical-range concentrations of sildenafil in fetal lambs, free from placental and maternal interference.

IMPLICATIONS OF ALL THE AVAILABLE EVIDENCE

We demonstrated self-limiting pulmonary vasodilation, a decrease of both systemic arterial pressures and circuit flows, induced by clinical range concentrations of sildenafil, without the development of fetal acidosis. This paves the way for further investigation of prenatal sildenafil in fetal lambs on extracorporeal support. A dose of 0.5 mg/kg/24 h offered the best trade-off between rapid achievement of target concentrations and shortest duration of systemic effects. This is also the first study using the EXTEND as a model for pharmacotherapy during pregnancy.

Sildenafil citrate-loaded targeted nanostructured lipid carrier enhances receptivity potential of endometrial cells via LIF and VEGF upregulation

The main objective of this research is to prepare sildenafil citrate (SC)-loaded arginyl-glycyl-aspartic acid (RGD)-containing nanostructured lipid carrier (SC-loaded NLC-RGD) and evaluate their effects on the receptivity potential of endometrial cells. Hot homogenization method was used to prepare SC-loaded NLC-RGD. Then, size, drug encapsulation, and morphology of prepared nanoparticles were studied by photon correlation spectroscopy technic, ultrafiltration method, and scanning electron microscopy, respectively. Subsequently, the influence of SC-loaded NLC-RGD on endometrial receptivity was evaluated by in vitro implantation assay. Finally, expression of vascular endothelial growth factor (VEGF), leukemia inhibitory factor (LIF), and integrin beta 3 (as endometrial receptivity markers) was assessed in SC-loaded NLC-RGD-treated endometrial cells by reverse transcription polymerase chain reaction (RT-PCR). Particles with a nano-size diameter (92.7 nm), appropriate polydispersity index (0.21), spherical morphology, and acceptable loading efficiency were prepared. In vitro implantation assay showed that SC, SC-loaded NLC, and SC-loaded NLC-RGD improve the rate of endometrial attachment potential by 1.6 ± 0.4, 1.7 ± 0.3, and 2.3 ± 0.3 times, respectively. Analysis of RT-PCR results showed the enhancing mRNA of LIF and VEGF in SC-treated endometrial cells. Results also confirmed the higher influence of SC-loaded NLC-RGD on gene expression patterns in comparison to SC. Using NLC-RGD as a carrier to deliver SC to endometrial cells is an effective approach to improve endometrial receptivity. Upregulation of LIF and VEGF is the probable mechanism by which SC enhances the endometrial receptivity potential.

Evaluation and Management of Suspected Fetal Growth Restriction

Impaired fetal growth owing to placental insufficiency is a major contributor to adverse perinatal outcomes. No intervention is available that improves outcomes by changing the pathophysiologic process. Monitoring in early-onset fetal growth restriction (FGR) focuses on optimizing the timing of iatrogenic preterm delivery using cardiotocography and Doppler ultrasound. In late-onset FGR, identifying the fetus at risk for immediate hypoxia and who benefits from expedited delivery is challenging. It is likely that studies in the next decade will provide evidence how to best integrate different monitoring variables and other prognosticators in risk models that are aimed to optimize individual treatment strategies.

Fetal Growth Restriction: Does an Integrated Maternal Hemodynamic-Placental Model Fit Better?

In recent years, a growing interest has arisen regarding the possible relationship between adverse pregnancy outcomes (APOs) and inadequate maternal hemodynamic adaptations to the pregnancy. A possible association between "placental syndromes," such as preeclampsia (PE) and fetal growth restriction (FGR), and subsequent maternal cardiovascular diseases (CVD) later in life has been reported. The two subtypes of FGR show different pathogenetic and clinical features. Defective placentation, due to a poor trophoblastic invasion of the maternal spiral arteries, is believed to play a central role in the pathogenesis of early-onset PE and FGR. Since placental functioning is dependent on the maternal cardiovascular system, a pre-existent or subsequent cardiovascular impairment may play a key role in the pathogenesis of early-onset FGR. Late FGR does not seem to be determined by a primary abnormal placentation in the first trimester. The pathological pathway of late-onset FGR may be due to a primary maternal cardiovascular maladaptation: CV system shows a flat profile and remains similar to those of non-pregnant women. Since the second trimester, when the placenta is already developed and increases its functional request, a hypovolemic state could lead to placental hypoperfusion and to an altered maturation of the placental villous tree and therefore to an altered fetal growth. Thus, this review focalizes on the possible relationship between maternal cardiac function and placentation in the development of both early and late-onset FGR. A better understanding of maternal hemodynamics in pregnancies complicated by FGR could bring various benefits in clinical practice, improving screening and therapeutic tools.

Inadequate evaluation of potential side effects of sildenafil in preterm stopped Dutch trial

Recently a drug trial in the Netherlands in which the efficacy of oral sildenafil was compared to placebo in women bearing children with fetal growth restriction was stopped early because of very harmful side effects to the babies. There were quite some unwanted and unscientific aspects related to this study and the manner in which the side effects were communicated to the patients and the community. These have not gained the attention they ought to have. We therefore made an analysis of the basic problems which aims to prevent that the trust in medical research will be weakened.

Transplacental Transfer and Fetal Pharmacodynamics of Sildenafil in the Pregnant Sheep Model

BACKGROUND

Sildenafil is a phosphodiesterase-5 inhibitor considered for antenatal use for a variety of indications. We sought to assess sildenafil pharmacokinetics in the pregnant ewe and fetus and evaluate its physiological fetal effects.

METHODS

Twelve fetal lambs (127-133 days GA, term 145) were chronically catheterized in utero. Ewes received different doses of sildenafil, either via subcutaneous injection (1.6, 2.0 mg/kg/day) or intravenous (IV) infusion (3, 5, 7, 10, and 12 mg/kg/day). Maternal and fetal sildenafil concentrations and metabolic status (blood gas analysis) were measured at given intervals. The fetal heart rate, pulmonary blood flow, systemic and aortic pressure, and maternal uterine artery pressure were continuously monitored.

RESULTS

The transplacental sildenafil transfer was 2.9% (range: 1.4-7.8%), preventing attainment of fetal target concentrations without toxic maternal levels. IV sildenafil infusion induced an immediate, temporary, dose-dependent reduction of pulmonary vascular resistance (38-78%) and increased both pulmonary blood flow (32-132%) and heart rate (13-49%), with limited nonlinear dose-dependent effects on systemic and pulmonary pressures. Fetal and maternal blood gases and maternal uterine artery pressures were unaffected by sildenafil infusion.

CONCLUSION

In sheep, transplacental transfer of sildenafil is extremely low. Though, minimal fetal sildenafil concentrations induce an acute transient pulmonary vasodilation, well-tolerated by the fetus and ewe.

Emerging antenatal therapies for congenital diaphragmatic hernia-induced pulmonary hypertension in preclinical models

Congenital diaphragmatic hernia (CDH)-related deaths are the largest contributor to in-hospital neonatal deaths in children with congenital malformations. Morbidity and mortality in CDH are directly related to the development of pulmonary hypertension (PH). Current treatment consists of supportive measures. To date, no pharmacotherapy has been shown to effectively reverse the hallmark finding of pulmonary vascular remodeling that is associated with pulmonary hypertension in CDH (CDH-PH). As such, there is a great need for novel therapies to effectively manage CDH-PH. Our review aims to evaluate emerging therapies, and specifically focuses on those that are still under investigation and not approved for clinical use by the Food and Drug Administration. Therapies were categorized into antenatal pharmacotherapies or antenatal regenerative therapies and assessed on their method of administration, safety profile, the effect on pulmonary vascular pathophysiology, and overall efficacy. In general, emerging antenatal pharmaceutical and regenerative treatments primarily aim to alleviate pulmonary vascular remodeling by restoring normal function and levels of key regulatory factors involved in pulmonary vascular development and/or in promoting angiogenesis. Overall, while these emerging therapies show great promise for the management of CDH-PH, most require further assessment of safety and efficacy in preclinical models before translation into the clinical setting. IMPACT: Emerging antenatal therapies for congenital diaphragmatic hernia-induced pulmonary hypertension (CDH-PH) show promise to effectively mitigate vascular remodeling in preclinical models. Further investigation is needed in preclinical and human studies to evaluate safety and efficacy prior to translation into the clinical arena. This review offers a comprehensive and up-to-date summary of emerging therapies currently under investigation in experimental animal models. There is no cure for CDH-PH. This review explores emerging therapeutic options for the treatment of CDH-PH and evaluates their impact on key molecular pathways and clinical markers of disease to determine efficacy in the preclinical stage.

A pilot study on investigating the role of Salvia miltiorrhiza in fetal growth restriction

To date there is no effective treatment for pregnancies complicated by fetal growth restriction (FGR). Salvia miltiorrhiza, a traditional Chinese herb has been shown to promote blood flow and improve microcirculatory disturbance. In this pilot study, we evaluated whether S. miltiorrhiza can potentially become a possible therapy for FGR. Nineteen pregnant women with FGR were treated with S. miltiorrhiza and ATP supplementation for an average of 7 days, and 17 cases received ATP supplementation as controls. The estimated fetal weights (EFWs) were measured by ultrasound after treatment, and the birthweights were recorded after birth. After treatment with S. miltiorrhiza, 7 (37%) FGR cases showed an increase in EFW to above the 10th percentile, compared with 4 (23%) FGR cases in controls (odds ratio: 1.896, 95% confidence limits (CLs): 0.44-8.144). At delivery, 10 (53%) FGR cases in the treatment group delivered babies with a birthweight above the 10th percentile, compared with 6 (35%) FGR cases in the control group (odds ratio: 2.037, 95% CL: 0.532-7.793); 80 or 64% FGR cases in the treatment group showed an increase in fetal abdominal circumference (AC) or biparietal diameter (BPD) above the 10th percentile before delivery. While 44 or 30% FGR cases in the control group showed an increase in AC or BPD. No improvement of head circumference (HC) or femur length (FL) was seen. These pilot data suggest the need for multicenter randomized clinical trials on the potential of S. miltiorrhiza to improve perinatal outcome in pregnant women complicated by FGR.

Adjuvant Vaginal Use of Sildenafil Citrate in a Hormone Replacement Cycle Improved Live Birth Rates Among 10,069 Women During First Frozen Embryo Transfers

Purpose

To investigate the effects of sildenafil citrate (SC) on live birth rates (LBR) during women undergoing their first frozen embryo transfers (FET) with hormone replacement therapy (HRT).

Patients and Methods

This retrospective cohort study included a total of 10,069 infertile women with adequate endometrial thickness (≥7 mm when progesterone was initiated) in their first FET cycle with hormone replacement therapy. Women received either vaginal SC or no adjuvant during their first transfer cycle depending on patient or physician preference. In the sildenafil group, 1098 women underwent HRT FET with adjuvant vaginal use of SC, and 8971 women were included as controls. The primary outcome measure was LBR, defined as the likelihood of live birth per transfer cycle. Endometrial thickness (EMT), implantation, chemical pregnancy, clinical pregnancy, miscarriage, ongoing pregnancy, birth weight and preterm delivery (PTB) were also recorded.

Results

Baseline characteristics were comparable between the two groups. In the crude analysis, the unadjusted LBR was significantly higher in the vaginal SC group (scHRT-FET) than in the control group (HRT-FET) (40.3% vs 36.1%). After adjustment for 12 pregnancy-related confounding factors, logistic regression analysis showed that LBR remained significantly higher in the scHRT-FET group than in the HRT-FET group (adjusted odds ratio [aOR] 1.31, 95% confidence interval [CI] 1.14–1.49). Furthermore, after adjustment, the ongoing pregnancy rate was significantly higher (aOR 1.29, 95% CI 1.13–1.47), and the miscarriage rate was significantly lower (aOR 0.58, 95% CI 0.43–0.77), in the scHRT-FET group compared to the HRT-FET group. Adjuvant vaginal use of SC did not increase the endometrial thickness and had no significant effect on birth weight or PTB.

Conclusion

Adjuvant vaginal use of SC in HRT FET was associated with higher LBR and improved pregnancy outcomes in an infertile population with adequate endometrial thickness. The beneficial effect of SC may be due not to an increase in EMT but instead to improve endometrial blood flow and receptivity, which might merit clinicians’ attention for improving general IVF practices.

Phosphodiesterase type 5 inhibitor use among pregnant and reproductive-age women in the United States

PURPOSE

To assess the prevalence and potential indications of PDE5 inhibitor use among pregnant and reproductive-age women in the United States.

METHODS

We identified women 15 to 50 years with a livebirth from January 2001 through March 2018 in Sentinel Database. We assessed the prevalence of PDE5 inhibitor use prior to and during pregnancy by trimester, identified potential on- and off-label indications using predefined diagnosis codes recorded within 90 days before the estimated last menstrual period through delivery. Separately, we used data from IQVIA's National Prescription Audit and Total Patient Tracker to estimate the dispensed prescriptions for PDE5 inhibitors and the number of patients with PDE5 inhibitor prescriptions.

RESULTS

We identified approximately 3.3 million pregnancies during 2001 to 2018, 96 of which had PDE5 inhibitor use during pregnancy. Prevalence of PDE5 inhibitor use was 2.61, 0.62, and 0.62 per 100, 000 live-born pregnancies during the first, second, or third trimesters, respectively. Among women exposed to a PDE5 inhibitor from 90 days before conception to the end of pregnancy, 25.0%, 31.1%, and 15.5% had a diagnosis code for fetal growth restriction, preeclampsia, and pulmonary arterial hypertension. In IQVIA data, an estimated 223, 000 prescriptions from July 2015 through June 2018 and 58, 000 women received prescriptions for PDE5 inhibitors in 2017, of whom approximately 15, 000 (26%) were aged 15 to 50 years.

CONCLUSION

We found a low prevalence of PDE5 inhibitor use in pregnant and reproductive-age women. Given the very low prevalence of use and the inconsistency of neonatal mortality data across STRIDER centers, the risk to public health is low at present.

Vascular mechanisms and molecular targets in hypertensive pregnancy and preeclampsia

Preeclampsia is a major complication of pregnancy manifested as hypertension and often intrauterine growth restriction, but the underlying pathophysiological mechanisms are unclear. Predisposing genetic and environmental factors cause placental maladaptations leading to defective placentation, apoptosis of invasive cytotrophoblasts, inadequate expansive remodeling of the spiral arteries, reduced uteroplacental perfusion pressure, and placental ischemia. Placental ischemia promotes the release of bioactive factors into the maternal circulation, causing an imbalance between antiangiogenic soluble fms-like tyrosine kinase-1 and soluble endoglin and proangiogenic vascular endothelial growth factor, placental growth factor, and transforming growth factor-β. Placental ischemia also stimulates the release of proinflammatory cytokines, hypoxia-inducible factor, reactive oxygen species, and angiotensin type 1 receptor agonistic autoantibodies. These circulating factors target the vascular endothelium, causing generalized endotheliosis in systemic, renal, cerebral, and hepatic vessels, leading to decreases in endothelium-derived vasodilators such as nitric oxide, prostacyclin, and hyperpolarization factor and increases in vasoconstrictors such as endothelin-1 and thromboxane A₂. The bioactive factors also target vascular smooth muscle and enhance the mechanisms of vascular contraction, including cytosolic Ca²⁺, protein kinase C, and Rho-kinase. The bioactive factors could also target matrix metalloproteinases and the extracellular matrix, causing inadequate vascular remodeling, increased arterial stiffening, and further increases in vascular resistance and hypertension. As therapeutic options are limited, understanding the underlying vascular mechanisms and molecular targets should help design new tools for the detection and management of hypertension in pregnancy and preeclampsia.

Preeclampsia beyond pregnancy: long-term consequences for mother and child

Preeclampsia is defined as new-onset hypertension after the 20th wk of gestation along with evidence of maternal organ failure. Rates of preeclampsia have steadily increased over the past 30 yr, affecting ∼4% of pregnancies in the United States and causing a high economic burden (22, 69). The pathogenesis is multifactorial, with acknowledged contributions by placental, vascular, renal, and immunological dysfunction. Treatment is limited, commonly using symptomatic management and/or early delivery of the fetus (6). Along with significant peripartum morbidity and mortality, current research continues to demonstrate that the consequences of preeclampsia extend far beyond preterm delivery. It has lasting effects for both mother and child, resulting in increased susceptibility to hypertension and chronic kidney disease (45, 54, 115, 116), yielding lifelong risk to both individuals. This review discusses recent guideline updates and recommendations along with current research on these long-term consequences of preeclampsia.

Maternal Sildenafil vs Placebo in Pregnant Women With Severe Early-Onset Fetal Growth Restriction: A Randomized Clinical Trial

IMPORTANCE

Severe early onset fetal growth restriction caused by placental dysfunction leads to high rates of perinatal mortality and neonatal morbidity. The phosphodiesterase 5 inhibitor, sildenafil, inhibits cyclic guanosine monophosphate hydrolysis, thereby activating the effects of nitric oxide, and might improve uteroplacental function and subsequent perinatal outcomes.

OBJECTIVE

To determine whether sildenafil reduces perinatal mortality or major morbidity.

DESIGN, SETTING, AND PARTICIPANTS

This placebo-controlled randomized clinical trial was conducted at 10 tertiary referral centers and 1 general hospital in the Netherlands from January 20, 2015, to July 16, 2018. Participants included pregnant women between 20 and 30 weeks of gestation with severe fetal growth restriction, defined as fetal abdominal circumference below the third percentile or estimated fetal weight below the fifth percentile combined with Dopplers measurements outside reference ranges or a maternal hypertensive disorder. The trial was stopped early owing to safety concerns on July 19, 2018, whereas benefit on the primary outcome was unlikely. Data were analyzed from January 20, 2015, to January 18, 2019. The prespecified primary analysis was an intention-to-treat analysis including all randomized participants.

INTERVENTIONS

Participants were randomized to sildenafil, 25 mg, 3 times a day vs placebo.

MAIN OUTCOMES AND MEASURES

The primary outcome was a composite of perinatal mortality or major neonatal morbidity until hospital discharge.

RESULTS

Out of 360 planned participants, a total of 216 pregnant women were included, with 108 women randomized to sildenafil (median gestational age at randomization, 24 weeks 5 days [interquartile range, 23 weeks 3 days to 25 weeks 5 days]; mean [SD] estimated fetal weight, 458 [160] g) and 108 women randomized to placebo (median gestational age, 25 weeks 0 days [interquartile range, 22 weeks 5 days to 26 weeks 3 days]; mean [SD] estimated fetal weight, 464 [186] g). In July 2018, the trial was halted owing to concerns that sildenafil may cause neonatal pulmonary hypertension, whereas benefit on the primary outcome was unlikely. The primary outcome, perinatal mortality or major neonatal morbidity, occurred in the offspring of 65 participants (60.2%) allocated to sildenafil vs 58 participants (54.2%) allocated to placebo (relative risk, 1.11; 95% CI, 0.88-1.40; P = .38). Pulmonary hypertension, a predefined outcome important for monitoring safety, occurred in 16 neonates (18.8%) in the sildenafil group vs 4 neonates (5.1%) in the placebo group (relative risk, 3.67; 95% CI, 1.28-10.51; P = .008).

CONCLUSIONS AND RELEVANCE

These findings suggest that antenatal maternal sildenafil administration for severe early onset fetal growth restriction did not reduce the risk of perinatal mortality or major neonatal morbidity. The results suggest that sildenafil may increase the risk of neonatal pulmonary hypertension.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02277132.

Addition of sildenafil citrate for treatment of severe intrauterine growth restriction: a double blind randomized placebo controlled trial

Background: Severe intrauterine growth restriction complicates approximately 0.4% of the pregnancies. It increases the risk of perinatal morbidity and mortality.Subjects and methods: A double blind placebo controlled trial was conducted in Beni Suef University hospitals during 2017. It included 46 pregnant women with severe intrauterine growth restriction. Women were randomly allocated into two groups each included 23 patients. Intervention group received sildenafil citrate 20 mg orally three times a day, in addition to fish oil and zinc supplementation. Control group received tablets similar to sildenafil and the same treatment as intervention group. Primary outcomes included improvement in umbilical and middle cerebral arteries pulsatility indices and abdominal circumference.Results: Umbilical and middle cerebral arteries Doppler indices showed significant difference between groups after intake of sildenafil. Umbilical artery pulsatility index decreased significantly (p value = .001) while middle cerebral artery pulsatility index increased significantly in intervention group (p value0.001). Moreover, abdominal circumference growth velocity improved after two weeks of sildenafil intake (p value = .001).Conclusions: Sildenafil citrate may improve uteroplacental and fetal cerebral perfusion in pregnancies complicated by severe intrauterine growth restriction. It also improves abdominal circumference growth velocity. A wide scale randomized trials are needed for evaluation of neonatal and long term morbidity and mortality outcomes of pregnancies treated by sildenafil citrate.

A bibliometric analysis of Intrauterine Growth Restriction research

Intrauterine growth restriction (IUGR) is not a new subject in pregnancy. Nevertheless, this concept has newly begun to be integrated into pregnancy studies. We recognized articles that were published in English from 1977 to 2019 through electronic searches of the Web of Science™ database. The WoS database was searched for all published articles that compared preeclampsia from 1977 to January 2020. About 1469 documents in obstetrics and gynecology areas were analyzed in WoS database. VOSviewer software was employed to visualize the networks. The survey resulted in a 1469 published documents from 1977 to 2020. 'Gratacos' from Spain and 'Cetin' from Italy contributed the most publications. The greatest contribution came from the 'USA' (n = 498), 'Italy' (n = 155), and 'England' (n = 147). Furthermore, our results found that among these journals, the 'AJOG' (n = 318) and the 'Reproductive Sciences' (n = 209) published the largest number of papers. The top 100 most cited papers showed that 30% were reported in the 'AJOG'. About half the articles were published in the last decade and the most common studies were research paper (77%). The co-occurrence and co-citation analysis showed that the study formed four clusters. Finally, the strategic map was designed. We found that there existed an increasing trend in the large amount of publication on IUGR from 1977 to 2020. The number of studies in IUGR has substantially improved in the last decade. Authors from the 'USA' appeared the most proactive in addressing the IUGR area. By studying these articles, we propose important to support not only for grinding the IUGR challenges field but also for designing a new trend in this area.

Sildenafil for Antenatal Treatment of Congenital Diaphragmatic Hernia: From Bench to Bedside

BACKGROUND

Persistent pulmonary hypertension (PPH) is one of the main causes of mortality and morbidity in infants affected by congenital diaphragmatic hernia (CDH). Since the structural changes that lead to PPH take place already in utero, a treatment starting in the prenatal phase may prevent the occurrence of this complication.

OBJECTIVE

To summarize the development process of antenatal sildenafil for CDH.

METHODS

The pharmacokinetics and efficacy of sildenafil have been assessed in the rat and the rabbit model. The transfer of the drug through the human placenta has been measured with the ex-vivo placenta perfusion model. Results from this experiment are being incorporated in a pregnancy-physiologically based pharmacokinetic (p- PBPK) model. A phase I-IIb placental transfer and safety study is ongoing.

RESULTS

Sildenafil administration to pregnant rats and rabbits led to therapeutic foetal drug levels without maternal and foetal toxicity, although it was associated with impaired vascular development in foetuses with nonhypoplastic lungs. Peak concentrations and 24-hour exposure were higher in pregnant rabbits compared to nonpregnant ones. In rat and rabbit foetuses with CDH, sildenafil rescued the lung vascular anomalies and partially improved parenchymal development. Sildenafil crossed the human placenta at a high rate ex-vivo, independently from the initial maternal concentration.

CONCLUSION

There is preclinical evidence that maternally administered sildenafil prevents the vascular changes that lead to PPH in CDH newborns. The phase I/IIb clinical study together with the p-PBPK model will define the maternal dose needed for a therapeutic effect in the foetus. Foetal safety will be investigated both in the clinical study and in the sheep. The final step will be a multicentre, randomized, placebo-controlled trial.

Effect of sildenafil on maternal hemodynamics in pregnancies complicated by severe early-onset fetal growth restriction: planned subgroup analysis from a multicenter randomized placebo-controlled double-blind trial

OBJECTIVES

Fetal growth restriction (FGR) is associated with maternal cardiovascular changes. Sildenafil, a phosphodiesterase type-5 inhibitor, potentiates the actions of nitric oxide, and it has been suggested that it alters maternal hemodynamics, potentially improving placental perfusion. Recently, the Dutch STRIDER trial was stopped prematurely owing to excess neonatal mortality secondary to pulmonary hypertension. The main aim of this study was to investigate the effect of sildenafil on maternal hemodynamics in pregnancies with severe early-onset FGR.

METHODS

This was a cardiovascular substudy within a UK multicenter, placebo-controlled trial, in which 135 women with a singleton pregnancy and severe early-onset FGR (defined as a combination of estimated fetal weight or abdominal circumference below the 10^th centile and absent/reversed end-diastolic flow in the umbilical artery on Doppler velocimetry, diagnosed between 22 + 0 and 29 + 6 weeks' gestation) were assigned randomly to receive either 25 mg sildenafil three times daily or placebo until 32 + 0 weeks' gestation or delivery. Maternal blood pressure (BP), heart rate (HR), augmentation index, pulse wave velocity (PWV), cardiac output, stroke volume (SV) and total peripheral resistance were recorded before randomization, 1-2 h and 48-72 h post-randomization, and 24-48 h postnatally. For continuous data, analysis was performed using repeated measures ANOVA methods including terms for timepoint, treatment allocation and their interaction.

RESULTS

Included were 134 women assigned randomly to sildenafil (n = 69) or placebo (n = 65) who had maternal BP and HR recorded at baseline. At 1-2 h post-randomization, compared with baseline values, sildenafil increased maternal HR by 4 bpm more than did placebo (mean difference, 5.00 bpm (95% CI, 1.00-12.00 bpm) vs 1.25 bpm (95% CI, -5.38 to 7.88 bpm); P = 0.004) and reduced systolic BP by 1 mmHg more (mean difference, -4.13 mmHg (95% CI, -9.94 to 1.44 mmHg) vs -2.75 mmHg (95% CI, -7.50 to 5.25 mmHg); P = 0.048). Even after adjusting for maternal mean arterial pressure, sildenafil reduced aortic PWV by 0.60 m/s more than did placebo (mean difference, -0.90 m/s (95% CI, -1.31 to -0.51 m/s) vs -0.26 m/s (95% CI, -0.75 to 0.59 m/s); P = 0.001). Sildenafil was associated with a non-significantly greater decrease in SV index after 1-2 h post-randomization than was placebo (mean difference, -5.50 mL/m² (95% CI, -11.00 to -0.50 mL/m² ) vs 0.00 mL/m² (95% CI, -5.00 to 4.00 mL/m² ); P = 0.056).

CONCLUSIONS

Sildenafil in a dose of 25 mg three times daily increases HR, reduces BP and reduces arterial stiffness in pregnancies complicated by severe early-onset FGR. These changes are short term, modest and consistent with the anticipated vasodilatory effect. They have no short- or long-term clinical impact on the mother. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Effects of nifedipine and sildenafil on placental hemodynamics and gas exchange during fetal hypoxemia in a chronic sheep model

INTRODUCTION

We hypothesized that nifedipine and sildenafil would have no detrimental effects on placental hemodynamics and gas exchange under fetal hypoxemia.

METHODS

In 33 chronically instrumented fetal sheep, placental volume blood flow (Q_Plac) and umbilical artery (UA) vascular impedance were measured by Doppler ultrasonography. Fetal carotid artery blood pressure and blood gas values were monitored. After baseline data collection, maternal and fetal hypoxemia were induced. Following hypoxemia phase data collection, 12 fetuses received sildenafil and 9 fetuses nifedipine infusion, and 12 fetuses served as controls receiving saline infusion. Data were collected 30 and 120 min after infusion was started. Then maternal oxygenation was normalized and normoxemia phase data were collected, while infusion was continued.

RESULTS

Hypoxemia significantly decreased fetal pO₂ and blood pressure. In the sildenafil group at 30- and 120-min hypoxemia + infusion phases, fetal blood pressure and Q_Plac were significantly lower and pCO₂ higher than at baseline without returning to baseline level at normoxemia + infusion phase. In hypoxemia, nifedipine did not affect fetal blood pressure or placental hemodynamics. Both in the sildenafil and nifedipine groups, fetal pO₂ remained significantly lower at normoxemia + infusion phase than in the control group. Umbilical artery vascular impedance did not change during the experiment.

DISCUSSION

In fetal hypoxemia, sildenafil had detrimental effects on placental hemodynamics that disturbed placental gas exchange. Nifedipine did not alter placental hemodynamics in hypoxemia but disturbed placental gas exchange upon returning to normoxemia. Umbilical artery vascular impedance did not reflect alterations in placental hemodynamics.

Antenatal sildenafil citrate treatment increases offspring blood pressure in the placental-specific Igf2 knockout mouse model of FGR

Fetal growth restriction (FGR), where a fetus fails to reach its genetic growth potential, affects up to 8% of pregnancies and is a major risk factor for stillbirth and adulthood morbidity. There are currently no treatments for FGR, but candidate therapies include the phosphodiesterase-5 inhibitor sildenafil citrate (SC). Randomized clinical trials in women demonstrated no effect of SC on fetal growth in cases of severe early onset FGR; however, long-term health outcomes on the offspring are unknown. This study aimed to assess the effect of antenatal SC treatment on metabolic and cardiovascular health in offspring by assessing postnatal weight gain, glucose tolerance, systolic blood pressure, and resistance artery function in a mouse model of FGR, the placental-specific insulin-like growth factor 2 (PO) knockout mouse. SC was administered subcutaneously (10 mg/kg) daily from embryonic day (E)12.5. Antenatal SC treatment did not alter fetal weight or viability but increased postnatal weight gain in wild-type (WT) female offspring (P < 0.05) and reduced glucose sensitivity in both WT (P < 0.01) and P0 (P < 0.05) female offspring compared with controls. Antenatal SC treatment increased systolic blood pressure in both male (WT vs. WT-SC: 117 ± 2 vs. 140 ± 3 mmHg, P < 0.0001; P0 vs. P0-SC: 113 ± 3 vs. 140 ± 4 mmHg, P < 0.0001; means ± SE) and female (WT vs. WT-SC: 121 ± 2 vs. 140 ± 2 mmHg, P < 0.0001; P0 vs. P0-SC: 117 ± 2 vs. 144 ± 4 mmHg, P < 0.0001) offspring at 8 and 13 wk of age. Increased systolic blood pressure was not attributed to altered mesenteric artery function. In utero exposure to SC may result in metabolic dysfunction and elevated blood pressure in later life.

NEW & NOTEWORTHY Sildenafil citrate (SC) is currently used to treat fetal growth restriction (FGR). We demonstrate that SC is ineffective at treating FGR, and leads to a substantial increase systolic blood pressure and alterations in glucose homeostasis in offspring. We therefore urge caution and suggest that further studies are required to assess the safety and efficacy of SC in utero, in addition to the implications on long-term health.

Early-onset fetal growth restriction: A systematic review on mortality and morbidity

INTRODUCTION

Severe early-onset fetal growth restriction is an obstetric condition with significant risks of perinatal mortality, major and minor neonatal morbidity, and long-term health sequelae. The prognosis of a fetus is influenced by the extent of prematurity and fetal weight. Clinical care is individually adjusted. In literature, survival rates vary and studies often only include live-born neonates with missing rates of antenatal death. This systematic review aims to summarize the literature on mortality and morbidity.

MATERIAL AND METHODS

A broad literature search was conducted in OVID MEDLINE from 2000 to 26 April 2019 to identify studies on fetal growth restriction and perinatal death. Studies were excluded when all included children were born before 2000 because (neonatal) health care has considerably improved since this period. Studies were included that described fetal growth restriction diagnosed before 32 weeks of gestation and antenatal mortality and neonatal mortality and/or morbidity as outcome. Quality of evidence was rated with the GRADE instrument.

RESULTS

Of the 2604 publications identified, 25 studies, reporting 2895 pregnancies, were included in the systematic review. Overall risk of bias in most studies was judged as low. The quality of evidence was generally rated as very low to moderate, except for 3 large well-designed randomized controlled trials. When combining all data on mortality, in 355 of 2895 pregnancies (12%) the fetus died antenatally, 192 died in the neonatal period (8% of live-born neonates) and 2347 (81% of all pregnancies) children survived. Of the neonatal morbidities recorded, respiratory distress syndrome (34% of the live-born neonates), retinopathy of prematurity (13%) and sepsis (30%) were most common. Of 476 children that underwent neurodevelopmental assessment, 58 (12% of surviving children, 9% of all pregnancies) suffered from cognitive impairment and/or cerebral palsy.

CONCLUSIONS

When combining the data of 25 included studies, survival in fetal growth restriction pregnancies, diagnosed before 32 weeks of gestation, was 81%. Neurodevelopmental impairment was assessed in a minority of surviving children. Individual prognostic counseling on the basis of these results is hampered by differences in patient and pregnancy characteristics within the included patient groups.

The effects of sildenafil in maternal and fetal outcomes in pregnancy: A systematic review and meta-analysis

BACKGROUND

The number of studies associating the use of sildenafil in gestation is increasing. This drug inhibits phosphodiesterase type 5 (PDE5), an enzyme responsible for degradation of nitric oxide, and its efficacy is greater in the placental territory, as the maternal side of the placenta have more PDE5 than other sites. For this reason, promising results have been observed related to the prevention of preeclampsia and intrauterine growth restriction and to improvement of maternal-fetal morbidity in cases of placental insufficiency.

OBJECTIVE

To evaluate the benefits of using sildenafil in pregnancy.

SEARCHED STRATEGY

MEDLINE, ClinicalTrials.gov, Embase, LILACS and Cochrane databases were searched through September 2018. There was no restriction in language or year of publication. This study was registered in PROSPERO (CRD42017060288).

SELECTION CRITERIA

Randomized clinical trials which used sildenafil for treatment or prevention of obstetric diseases compared with placebo were selected.

DATA COLLECTION AND ANALYSIS

The results were obtained using the inverse variance method for continuous variables and Man-Whitney for categorical variables.

MAIN RESULTS

Among a population of 598 pregnant women from the seven clinical trials included, 139 had pre-eclampsia, 275 had intrauterine growth restriction, and 184 had oligohydramnios. A significant increase of 222.58 grams [27.75 to 417.41] was observed in the fetal weight at birth of patients taking sildenafil. The other outcomes did not show any statistical significance. This may be due to the small number of patients used in each study and the great heterogeneity between the groups.

CONCLUSIONS

Sildenafil could be associated with increasing fetal weight at birth in placental insufficiency despite the limitations of this meta-analysis, even though more studies in this field are needed to introduce this drug into obstetric clinical practice.

Safety Evaluation of Tadalafil Treatment for Fetuses with Early-Onset Growth Restriction (TADAFER): Results from the Phase II Trial

Tadalafil is a phosphodiesterase 5 (PDE5) inhibitor with a long half-life, high selectivity, and rapid onset of action. Because the safety of using PDE5 inhibitors as therapeutic agents for fetal growth restriction (FGR) has been a problem worldwide, this paper primarily focuses on the safety assessments performed in the Tadalafil Treatment for Fetuses with Early-Onset Growth Restriction (TADAFER) II population. Neonatal and maternal adverse events were analyzed, in addition to fetal, neonatal, and infant death cases, six months after stopping the trial. Eighty-nine pregnant women with FGR were studied between September 2016 and March 2018 (45 and 44 in the tadalafil and conventional treatment groups, respectively). Seven (16%) deaths (four fetal, one neonatal, and two infant) in the control group, whereas only one neonatal death occurred in the tadalafil group. Although headache, facial flushing, and nasal hemorrhage occurred more frequently in the tadalafil group, these symptoms were Grade 1 and transient. In conclusion, this trial showed that tadalafil decreased the fetal and infant deaths associated with FGR. This is thought to be primarily due to pregnancy prolongation. Further studies are warranted to evaluate the efficacy of tadalafil in treating early-onset FGR.

Placental effects and transfer of sildenafil in healthy and preeclamptic conditions

Background

The phosphodiesterase-5 inhibitor (PDE5) sildenafil has emerged as a promising treatment for preeclampsia (PE). However, a sildenafil trial was recently halted due to lack of effect and increased neonatal morbidity.

Methods

Ex vivo dual-sided perfusion of an isolated cotyledon and wire-myography on chorionic plate arteries were performed to study the effects of sildenafil and the non-selective PDE inhibitor vinpocetine on the response to the NO donor sodium nitroprusside (SNP) under healthy and PE conditions. Ex vivo perfusion was also used to study placental transfer of sildenafil in 6 healthy and 2 PE placentas. Furthermore, placental mRNA and protein levels of eNOS, iNOS, PDE5 and PDE1 were quantified.

Findings

Sildenafil and vinpocetine significantly enhanced SNP responses in chorionic plate arteries of healthy, but not PE placentas. Only sildenafil acutely decreased baseline tension in arteries of both healthy and PE placentas. At steady state, the foetal-to-maternal transfer ratio of sildenafil was 0·37 ± 0·03 in healthy placentas versus 0·66 and 0·47 in the 2 PE placentas. mRNA and protein levels of PDE5, eNOS and iNOS were comparable in both groups, while PDE1 levels were lower in PE.

Interpretation

The absence of sildenafil-induced NO potentiation in arteries of PE placentas, combined with the non-PDE-mediated effects of sildenafil and the lack of PDE5 upregulation in PE, argue against sildenafil as the preferred drug of use in PE. Moreover, increased placental transfer of sildenafil in PE might underlie the neonatal morbidity in the STRIDER trial.

Fund

This study was funded by an mRACE Erasmus MC grant.

STRIDER NZAus: a multicentre randomised controlled trial of sildenafil therapy in early-onset fetal growth restriction

OBJECTIVE

To assess the effect of maternal sildenafil therapy on fetal growth in pregnancies with early-onset fetal growth restriction.

DESIGN

A randomised placebo-controlled trial.

SETTING

Thirteen maternal-fetal medicine units across New Zealand and Australia.

POPULATION

Women with singleton pregnancies affected by fetal growth restriction at 22⁺⁰ to 29⁺⁶ weeks.

METHODS

Women were randomised to oral administration of 25 mg sildenafil citrate or visually matching placebo three times daily until 32⁺⁰ weeks, birth or fetal death (whichever occurred first).

MAIN OUTCOME MEASURES

The primary outcome was the proportion of pregnancies with an increase in fetal growth velocity. Secondary outcomes included live birth, survival to hospital discharge free of major neonatal morbidity and pre-eclampsia.

RESULTS

Sildenafil did not affect the proportion of pregnancies with an increase in fetal growth velocity; 32/61 (52.5%) sildenafil-treated, 39/57 (68.4%) placebo-treated [adjusted odds ratio (OR) 0.49, 95% CI 0.23-1.05] and had no effect on abdominal circumference Z-scores (P = 0.61). Sildenafil use was associated with a lower mean uterine artery pulsatility index after 48 hours of treatment (1.56 versus 1.81; P = 0.02). The live birth rate was 56/63 (88.9%) for sildenafil-treated and 47/59 (79.7%) for placebo-treated (adjusted OR 2.50, 95% CI 0.80-7.79); survival to hospital discharge free of major neonatal morbidity was 42/63 (66.7%) for sildenafil-treated and 33/59 (55.9%) for placebo-treated (adjusted OR 1.93, 95% CI 0.84-4.45); and new-onset pre-eclampsia was 9/51 (17.7%) for sildenafil-treated and 14/55 (25.5%) for placebo-treated (OR 0.67, 95% CI 0.26-1.75).

CONCLUSIONS

Maternal sildenafil use had no effect on fetal growth velocity. Prospectively planned meta-analyses will determine whether sildenafil exerts other effects on maternal and fetal/neonatal wellbeing.

TWEETABLE ABSTRACT

Maternal sildenafil use has no beneficial effect on growth in early-onset FGR, but also no evidence of harm.

Establishment of a three-dimensional model to study human uterine angiogenesis

STUDY QUESTION

Can primary human uterine microvascular endothelial cells (UtMVECs) be used as a model to study uterine angiogenic responses in vitro that are relevant in pregnancy?

SUMMARY ANSWER

UtMVECs demonstrated angiogenic responses when stimulated with proangiogenic factors, including sphingosine 1-phosphate (S1P), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), physiological levels of wall shear stress (WSS), human chorionic gonadotropin (hCG) and various combinations of estrogen and progesterone.

WHAT IS KNOWN ALREADY

During sprouting angiogenesis, signaling from growth factors and cytokines induces a monolayer of quiescent endothelial cells (ECs) lining the vasculature to degrade the extracellular matrix and invade the surrounding tissue to form new capillaries. During pregnancy and the female reproductive cycle, the uterine endothelium becomes activated and undergoes sprouting angiogenesis to increase the size and number of blood vessels in the endometrium.

STUDY DESIGN, SIZE, DURATION

The study was designed to examine the angiogenic potential of primary human UtMVECs using the well-characterized human umbilical vein EC (HUVEC) line as a control to compare angiogenic potential. ECs were seeded onto three-dimensional (3D) collagen matrices, supplemented with known proangiogenic stimuli relevant to pregnancy and allowed to invade for 24 h. Sprouting responses were analyzed using manual and automated methods for quantification.

PARTICIPANTS/MATERIALS, SETTING, METHODS

RT-PCR, Western blot analysis and immunostaining were used to characterize UtMVECs. Angiogenic responses were examined using 3D invasion assays. Western blotting was used to confirm signaling responses after proangiogenic lipid, pharmacological inhibitor, and recombinant lentiviral treatments. All experiments were repeated at least three times.

MAIN RESULTS AND THE ROLE OF CHANCE

After ensuring that UtMVECs expressed the proper endothelial markers, we found that UtMVECs invade 3D collagen matrices dose-dependently in response to known proangiogenic stimuli (e.g. S1P, VEGF, bFGF, hCG, estrogen, progesterone and WSS) present during early pregnancy. Invasion responses were positively correlated with phosphorylation of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) and p42/p44 mitogen-activated protein kinase (ERK). Inhibition of these second messengers significantly impaired sprouting (P < 0.01). Gene silencing of membrane type 1-matrix metalloproteinase using multiple approaches completely abrogated sprouting (P < 0.001). Finally, UtMVECs displayed a unique ability to undergo sprouting in response to hCG, and combined estrogen and progesterone treatment.

LARGE SCALE DATA

Not applicable.

LIMITATIONS, REASONS FOR CAUTION

The study of uterine angiogenesis in vitro has limitations and any findings many not fully represent the in vivo state. However, these experiments do provide evidence for the ability of UtMVECs to be used in functional sprouting assays in a 3D environment, stimulated by physiological factors that are produced locally within the uterus during early pregnancy.

WIDER IMPLICATIONS OF THE FINDINGS

We show that UtMVECs can be used reliably to investigate how growth factors, hormones, lipids and other factors, such as flow, affect angiogenesis in the uterus.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by NIH award HL095786 to K.J.B. The authors have no conflicts of interest.

Tadalafil treatment in mice for preeclampsia with fetal growth restriction has neuro-benefic effects in offspring through modulating prenatal hypoxic conditions

We have demonstrated that tadalafil facilitates fetal growth in mice with L-NG-nitroarginine methyl ester (L-NAME)-induced preeclampsia (PE) with fetal growth restriction (FGR). Tadalafil is a selective phosphodiesterase 5 inhibitor that dilates the maternal blood sinuses in the placenta, thereby facilitating the growth of the fetus. The purpose of this study was to investigate the effects of tadalafil treatment for PE and FGR on the developing brain in FGR offspring using an L-NAME-induced mouse model of PE with FGR. A control group of dams received carboxymethylcellulose (CMC). L-NAME-treated groups received L-NAME dissolved in CMC from 11 days post coitum (d.p.c.). The L-NAME-treated dams were divided into two subgroups 14 d.p.c. One subgroup continued to receive L-NAME. The other subgroup received L-NAME with tadalafil suspended in CMC. Tadalafil treatment for PE with FGR reduced the expression of hypoxia-inducible factor-2α in the placenta and in the brain of the FGR fetus. Moreover, tadalafil treatment in utero shows improved synaptogenesis and myelination in FGR offspring on postnatal day 15 (P15) and P30. These results suggest that tadalafil treatment for PE with FGR not only facilitates fetal growth, but also has neuroprotective effects on the developing brain of FGR offspring through modulating prenatal hypoxic conditions.

Detailed statistical analysis plan for the Dutch STRIDER (Sildenafil TheRapy In Dismal prognosis Early-onset fetal growth Restriction) randomised clinical trial on sildenafil versus placebo for pregnant women with severe early onset fetal growth restriction

Objective

The objective of the Dutch Sildenafil therapy in dismal prognosis early onset fetal growth restriction (STRIDER) randomised clinical trial is to assess the beneficial and harmful effects of sildenafil versus placebo on fetal and neonatal mortality in pregnant women with severe early-onset fetal growth restriction. The objective of this detailed statistical analysis plan is to minimize the risks of selective reporting and data-driven analysis.

Setting

The setting is 10 tertiary care hospitals and one secondary care hospital in The Netherlands.

Participants

The participants will be 360 pregnant women with severe early-onset fetal growth restriction.

Interventions

The intervention is sildenafil 25 mg or placebo orally three times a day.

Primary and secondary outcome measures

The primary outcome is a composite of death or major neonatal morbidity assessed at hospital discharge. The secondary outcomes are neurodevelopmental impairment; mean scores of the Bayley III cognitive and motor assessment; the proportion of patients experiencing either preeclampsia or haemolysis, elevated liver enzymes, and low platelets syndrome; pulsatility index of uterine arteries, umbilical artery, and middle cerebral artery; birthweight; and gestational age at either delivery or intra-uterine death.

Results

A detailed statistical analysis is presented, including pre-defined exploratory outcomes and planned subgroup analyses. One interim analysis after 180 patients had completed the study was planned and a strategy to minimise the risks of type I errors due to repetitive testing is presented. During review of this manuscript the interim analysis was performed by the Data Safety Monitoring Board and early stopping of the trial was recommended. Final analyses will be conducted independently by two statistically qualified persons following the present plan.

Conclusion

This pre-specified statistical analysis plan was written and submitted without knowledge of the unblinded data and updated after stopping of the trial at interim analysis.

Trial registration

ClinicalTrials.gov, NCT02277132. Registered on 29 September 2014.

Original protocol for the study: doi:10.5281/zenodo.56148

Use of sildenafil citrate in cases of intrauterine growth restriction (IUGR); a prospective trial

OBJECTIVE

Intrauterine growth restriction (IUGR) is one of the most serious complications of pregnancy. Up to date, there is no evidence of achieving antenatal treatment of IUGR with abnormal placentation. Although, Sildenafil citrate has shown promising results, there are no firm conclusion till now. The aim of our study is to evaluate the use of Sildenafil citrate in the treatment of IUGR cases associated with impaired placental circulation.

MATERIALS AND METHODS

This was a prospective non-randomized study conducted at Mansoura university hospitals starting from March 2016 till October 2017. The studied population included singleton pregnancy and suffering from IUGR associated with impaired placental circulation.

RESULTS

This study included 50 pregnant women. Cases were divided into two groups. The first group received sildenafil citrate and the second control group did not receive sildenafil citrate. After 4 weeks after the 1st dose of Sildenafil significant decrease in umbilical artery Doppler indices. There was a statistically significant difference in the mean birth weight at delivery and neonatal admission to the newborn nursery in sildenafil group.

CONCLUSION

sildenafil citrate treatment may present a new hope towards better perinatal outcomes for pregnancies complicated by IUGR and impaired placental circulation that may help to decrease neonatal admission to the newborn nursery.

Sildenafil crosses the placenta at therapeutic levels in a dually perfused human cotyledon model

BACKGROUND

Sildenafil already is administered during gestation in patients with pulmonary hypertension and is under evaluation as a treatment for several pregnancy complications, such as preeclampsia and intrauterine growth restriction. Animal studies have shown a potential therapeutic effect of the drug in fetuses with congenital diaphragmatic hernia, rescuing peripheral pulmonary vasculature, and airway phenotype. When considering this drug for evaluation in a clinical trial, data on effective human placental drug passage are required.

OBJECTIVE

We quantified transplacental passage of sildenafil in the ex vivo dually perfused cotyledon model.

STUDY DESIGN

Six placentas that were collected after term delivery from healthy volunteers were cannulated and perfused dually. Sildenafil citrate was added to the maternal circulation at 2 different concentrations: 500 ng/mL, which represented the maximum tolerated concentration (n=3), and 50 ng/mL, which represented the therapeutic concentration (n=3). Samples were collected from both the fetal and the maternal reservoir at 0, 6, 30, 60, 90, 120, 150, and 180 minutes; the concentrations of sildenafil and its metabolite desmethyl-sildenafil were determined with the use of high performance liquid chromatography. The fetal/maternal concentration ratio was calculated for each timepoint. Transfer clearance was calculated as the rate of maternal to fetal passage/maternal concentration.

RESULTS

Sildenafil crossed the placenta at both maximal and therapeutic concentrations. Maternal and fetal levels reached a plateau at 90-120 minutes. Transfer clearance was the highest during the first hour of perfusion: 3.15 mL/min (range, 2.14-3.19 mL/min) for the maximum tolerated concentration and 3.07mL/min (range, 2.75-3.42 mL/min) for the therapeutic concentration (not significant). The fetomaternal concentration ratio significantly increased over time, up to 0.91±0.16 for the maximal concentration and 0.95±0.22 for the therapeutic concentration at the end of the perfusion (not significant). Desmethyl-sildenafil was not detected in any sample.

CONCLUSION

Sildenafil crosses the term placenta at a relatively high rate ex vivo, which suggests that there is sufficient placental transfer to reach clinically active fetal drug levels at the currently used maternal doses.

TADAFER II: Tadalafil treatment for fetal growth restriction - a study protocol for a multicenter randomised controlled phase II trial

INTRODUCTION

There is no proven therapy to reverse or ameliorate fetal growth restriction (FGR). Sildenafil, a selective phosphodiesterase 5 (PDE5) inhibitor, has been reported to potentially play a therapeutic role in FGR, but this has not been established. Tadalafil is also a selective PDE5 inhibitor. We have demonstrated the efficacy of tadalafil against FGR along with short-term outcomes and the feasibility of tadalafil treatment. Based on the hypothesis that tadalafil will safely increase the likelihood of increased fetal growth in FGR, we designed this phase II study to prospectively evaluate the efficacy and safety of tadalafil against FGR.

METHODS AND ANALYSIS

This study is a multicentre, randomised controlled phase II trial. A total of 140 fetuses with FGR will be enrolled from medical centres in Japan. Fetuses will be randomised to receive either the conventional management for FGR or a once-daily treatment with 20 mg of tadalafil along with the conventional management until delivery. The primary endpoint is fetal growth velocity from the first day of the protocol-defined treatment to birth (g/day). To minimise bias in terms of fetal baseline conditions and timing of delivery, a fetal indication for delivery was established in this study. The investigator will evaluate fetal baseline conditions at enrolment and will decide the timing of delivery based on this fetal indication. Infants will be followed up for development until 1.5 years of age.

ETHICS AND DISSEMINATION

This study was approved by the Institutional Review Board of Mie University Hospital and each participating institution. Our findings will be widely disseminated through peer-reviewed publications.

TRIAL REGISTRATION NUMBER

UMIN000023778.

Molecular determinants of microvascular dysfunction in hypertensive pregnancy and preeclampsia

Preeclampsia is a pregnancy-related disorder characterized by hypertension and often fetal intrauterine growth restriction, but the underlying mechanisms are unclear. Defective placentation and apoptosis of invasive cytotrophoblasts cause inadequate remodeling of spiral arteries, placental ischemia, and reduced uterine perfusion pressure (RUPP). RUPP causes imbalance between the anti-angiogenic factors soluble fms-like tyrosine kinase-1 and soluble endoglin and the pro-angiogenic vascular endothelial growth factor and placental growth factor, and stimulates the release of proinflammatory cytokines, hypoxia-inducible factor, reactive oxygen species, and angiotensin AT1 receptor agonistic autoantibodies. These circulating factors target the vascular endothelium, smooth muscle and various components of the extracellular matrix. Generalized endotheliosis in systemic, renal, cerebral, and hepatic vessels causes decreases in endothelium-derived vasodilators such as nitric oxide, prostacyclin and hyperpolarization factor, and increases in vasoconstrictors such as endothelin-1 and thromboxane A2. Enhanced mechanisms of vascular smooth muscle contraction, such as intracellular Ca2+ , protein kinase C, and Rho-kinase cause further increases in vasoconstriction. Changes in matrix metalloproteinases and extracellular matrix cause inadequate vascular remodeling and increased arterial stiffening, leading to further increases in vascular resistance and hypertension. Therapeutic options are currently limited, but understanding the molecular determinants of microvascular dysfunction could help in the design of new approaches for the prediction and management of preeclampsia.

Effect of sildenafil citrate treatment in the eNOS knockout mouse model of fetal growth restriction on long-term cardiometabolic outcomes in male offspring

Fetal growth restriction (FGR) is associated with an increased risk of hypertension, insulin resistance, obesity and cardiovascular disease in adulthood. Currently there are no effective treatments to reverse the course of FGR. This study used the eNOS knockout mouse (eNOS^-/-), a model of FGR, to determine the ability of sildenafil, a potential new treatment for FGR, to improve cardiovascular and metabolic outcomes in adult offspring following a complicated pregnancy. Pregnant eNOS^-/- and C57BL/6J control dams were randomised to sildenafil treatment (0.2 mg/ml in drinking water) or placebo at day 12.5 of gestation until birth. After weaning, male offspring were randomised to either a high fat (HFD; 45% kcal from fat) or normal chow diet (ND), and raised to either postnatal day 90 or 150. Growth and body composition, glucose tolerance, insulin resistance, systolic blood pressure and vascular function were analysed at both time-points. eNOS^-/- offspring were significantly smaller than their C57BL/6J controls at weaning and P90 (p < 0.01); at P150 they were a similar weight. Total adipose tissue deposition at P90 was significantly increased only in eNOS^-/- mice fed a HFD (p < 0.001). At P150 both C57BL/6J and eNOS^-/- offspring fed a HFD demonstrated significant adipose tissue deposition (p < 0.01), regardless of maternal treatment. Both diet and maternal sildenafil treatment had a significant effect on glucose tolerance. Glucose tolerance was significantly impaired in eNOS^-/- mice fed a HFD (p < 0.01); this was significant in offspring from both sildenafil and vehicle treated mothers at P90 and P150. Glucose tolerance was also impaired in C57BL/6J mice fed a HFD at both P90 and P150 (p < 0.01), but only in those also exposed to sildenafil. In these C57BL/6J mice, sildenafil was associated with impaired insulin sensitivity at P90 (p = 0.020) but increased insulin resistance at P150 (p = 0.019). Exposure to sildenafil was associated with a significant increase in systolic blood pressure in eNOS^-/- mice compared with their C57BL/6J diet controls at P150 (p < 0.05). Exposure to sildenafil had differing effects on vascular function in mesenteric arteries; it increased vasodilation in response to ACh in C57BL/6J mice, but was associated with a more constrictive phenotype in eNOS^-/- mice. eNOS^-/- mice demonstrate a number of impaired outcomes consistent with programmed cardiometabolic disease, particularly when faced with the 'second hit' of a HFD. Exposure to sildenafil treatment during pregnancy did not increase fetal growth or significantly improve adult metabolic or cardiac outcomes. Maternal sildenafil treatment was, however, associated with small impairments in glucose handling and an increase in blood pressure. This study highlights the importance of understanding the long-term effects of treatment during pregnancy in offspring from both complicated and healthy control pregnancies.

Antenatal sildenafil administration to prevent pulmonary hypertension in congenital diaphragmatic hernia (SToP-PH): study protocol for a phase I/IIb placenta transfer and safety study

Background

Congenital diaphragmatic hernia is an orphan disease with high neonatal mortality and significant morbidity. An important cause for this is pulmonary hypertension, for which no effective postnatal therapy is available to date. An innovative strategy aiming at treating or preventing pulmonary hypertension more effectively is urgently needed. Prenatal sildenafil administration to expectant mothers prevented fetal and neonatal vascular changes leading to pulmonary hypertension in several animal models, and is, therefore, a promising approach. Before transferring this antenatal medical approach to the clinic, more information is needed on transplacental transfer and safety of sildenafil in humans.

Methods

This is a randomized, investigator-blinded, double-armed, parallel-group, phase I/IIb study with as a primary objective to measure the in-vivo transplacental transfer of sildenafil in women in the second and early third trimester of pregnancy (sub-study 1; weeks: 20.0–32.6) and at term (sub-study 2; weeks: 36.6–40). Participants will be randomized to two different sildenafil doses: 25 or 75 mg. In sub-study 1, a single dose of the investigational product will be administered to women undergoing termination of pregnancy, and maternal and fetal blood samples will be collected for determination of sildenafil concentrations. In sub-study 2, sildenafil will be administered three times daily from 3 days before planned delivery until actual delivery, following which maternal and umbilical cord samples will be collected. Proxies of maternal and fetal tolerance as well as markers of fetal pulmonary vasodilation will also be measured.

Discussion

This is the first study evaluating in-vivo transplacental passage of sildenafil in humans.

Trial registration

EU Clinical Trials Register 2016–002619-17, validated on 12 August 2016.

Trial sponsor: UZ Leuven, Herestraat 49, 3000 Leuven.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2897-8) contains supplementary material, which is available to authorized users.

Melatonin Increases Fetal Weight in Wild-Type Mice but Not in Mouse Models of Fetal Growth Restriction

Fetal growth restriction (FGR) presents with an increased risk of stillbirth and childhood and adulthood morbidity. Melatonin, a neurohormone and antioxidant, has been suggested as having therapeutic benefit in FGR. We tested the hypothesis that melatonin would increase fetal growth in two mouse models of FGR which together represent a spectrum of the placental phenotypes in this complication: namely the endothelial nitric oxide synthase knockout mouse (eNOS^-/-) which presents with abnormal uteroplacental blood flow, and the placental specific Igf2 knockout mouse (P0^+/-) which demonstrates aberrant placental morphology akin to human FGR. Melatonin (5 μg/ml) was administered via drinking water from embryonic day (E)12.5 in C57Bl/6J wild-type (WT), eNOS^-/-, and P0^+/- mice. Melatonin supplementation significantly increased fetal weight in WT, but not eNOS^-/- or P0^+/- mice at E18.5. Melatonin did, however, significantly increase abdominal circumference in P0^+/- mice. Melatonin had no effect on placental weight in any group. Uterine arteries from eNOS^-/- mice demonstrated aberrant function compared with WT but melatonin treatment did not affect uterine artery vascular reactivity in either of these genotypes. Umbilical arteries from melatonin treated P0^+/- mice demonstrated increased relaxation in response to the nitric oxide donor SNP compared with control. The increased fetal weight in WT mice and abdominal circumference in P0^+/-, together with the lack of any effect in eNOS^-/-, suggest that the presence of eNOS is required for the growth promoting effects of melatonin. This study supports further work on the possibility of melatonin as a treatment for FGR.

Gestational Hypoxia and Developmental Plasticity

Hypoxia is one of the most common and severe challenges to the maintenance of homeostasis. Oxygen sensing is a property of all tissues, and the response to hypoxia is multidimensional involving complicated intracellular networks concerned with the transduction of hypoxia-induced responses. Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. Hypoxia during gestation impacts both the mother and fetal development through interactions with an individual's genetic traits acquired over multiple generations by natural selection and changes in gene expression patterns by altering the epigenetic code. Changes in the epigenome determine "genomic plasticity," i.e., the ability of genes to be differentially expressed according to environmental cues. The genomic plasticity defined by epigenomic mechanisms including DNA methylation, histone modifications, and noncoding RNAs during development is the mechanistic substrate for phenotypic programming that determines physiological response and risk for healthy or deleterious outcomes. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue. The complex molecular and epigenetic interactions that may impact an individual's physiology and developmental programming of health and disease later in life are discussed.