Low-dose aspirin reduces uteroplacental vascular impedance in early and mid gestation in IVF and ICSI patients: a randomized, placebo-controlled double-blind study

The effects of low-dose aspirin on preterm birth: a systematic review and meta-analysis of randomized controlled trials

AIM

To conduct a systematic review and meta-analysis of all randomized controlled trials (RCTs) that evaluated the efficacy of low-dose aspirin (LDA, ≤ 160 mg/day) on preventing preterm birth (PB).

METHODS

Five databases were screened from inception until June 25, 2023. The RCTs were assessed for quality according to Cochrane's risk of bias tool. The endpoints were summarized as risk ratio (RR) with 95% confidence interval (CI).

RESULTS

Overall, 40 RCTs were analyzed. LDA significantly decreased the risk of PB < 37 weeks (RR: 0.91, 95% CI 0.87, 0.96, p < 0.001, moderate certainty of evidence) with low between-study heterogeneity (I2 = 23.2%, p = 0.11), and PB < 34 weeks (RR: 0.78, 95% CI 0.61, 0.99, p = 0.04, low certainty of evidence) with high between-study heterogeneity (I2 = 58.3%, p = 0.01). There were no significant differences between both groups regarding the risk of spontaneous (RR: 0.94, 95% CI 0.83, 1.07, p = 0.37) and medically indicated (RR: 1.28, 95% CI 0.87, 1.88, p = 0.21) BP < 37 weeks. Sensitivity analysis revealed robustness for all outcomes, except for the risk of PB < 34 weeks. For PB < 37 weeks and PB < 34 weeks, publication bias was detected based on visual inspection of funnel plots for asymmetry and statistical significance for Egger's test (p = 0.009 and p = 0.0012, respectively).

CONCLUSION

LDA can significantly reduce the risk of PB < 37 and < 34 weeks. Nevertheless, further high-quality RCTs conducted in diverse populations, while accounting for potential confounding factors, are imperative to elucidate the optimal aspirin dosage, timing of initiation, and treatment duration for preventing preterm birth and to arrive at definitive conclusions.

Could Aspirin Treatment Modify the Assessment of the Uterine Arteries?

OBJECTIVE

 To analyze whether acetylsalicylic (ASA) intake modifies the mean uterine arteries pulsatility index (UtA-PI) at the 2^nd or 3^rd trimester in a cohort of pregnant women with abnormal mean UtA-PI at between 11 and 14 weeks of gestation.

METHODS

 This is a retrospective cohort study. Singleton pregnancies with abnormal mean UtA-PI at between 11 and 14 weeks of gestation were studied. The participants were divided into 3 groups: 1) If the participant did not take ASA during pregnancy; 2) If the participant took ASA before 14 weeks of gestation; and 3) If the participant took ASA after 14 weeks of gestation. The mean UtA-PI was evaluated at the 2^nd and 3^rd trimesters, and it was considered to improve when it decreased below the 95^th percentile. The prevalence ratio (PR) and the number needed to treat (NNT) were calculated.

RESULTS

 A total of 72 participants with a mean UtA-PI > 95^th percentile at the 1^st trimester of gestation were evaluated. Out of the 18 participants who took ASA, 8 participants started it before 14 weeks of gestation and 10 after. A total of 33.3% of these participants had improved the mean UtA-PI at the 2^nd and 3^rd trimesters of gestation, although it was not statistically significant (p = 0.154). The prevalence ratio was 0.95 (95% confidence interval [CI]: 0.31-1.89), but between the 1^st and 2^nd trimesters of gestation, the PR was 0.92 (95%CI: 0.21-0.99) and it was statistically significant.

CONCLUSION

 The present work demonstrates a modification of the mean UtA-PI in participants who took ASA compared with those who did not. It is important to check if ASA can modify the normal limits of uterine arteries because this could have an impact on surveillance.

Endothelium-Derived Hyperpolarizing Factor (EDHF) Mediates Acetylsalicylic Acid (Aspirin) Vasodilation of Pregnant Rat Mesenteric Arteries

Acetylsalicylic acid (aspirin) exhibits a broad range of activities, including analgesic, antipyretic, and antiplatelet properties. Recent clinical studies also recommend aspirin prophylaxis in women with a high risk of pre-eclampsia, a major complication of pregnancy characterized by hypertension. We investigated the effect of aspirin on mesenteric resistance arteries and found outdiscovered the molecular mechanism underlying this action. Aspirin (10⁻¹²–10⁻⁶ M) was tested on pregnant rat mesenteric resistance arteries by a pressurized arteriography. Aspirin was investigated in the presence of several inhibitors of: (a) nitric oxide synthase (L-NAME 2 × 10⁻⁴ M); (b) cyclooxygenase (Indomethacin, 10⁻⁵ M); (c) Ca²⁺-activated K⁺ channels (Kca): small conductance (SKca, Apamin, 10⁻⁷ M), intermediate conductance (IKca, TRAM34, 10⁻⁵ M), and big conductance (BKca, paxilline, 10⁻⁵ M); and (d) endothelial-derived hyperpolarizing factor (high KCl, 80 mM). Aspirin caused a concentration-dependent vasodilation. Aspirin-vasodilation was abolished by removal of endothelium or by high KCl. Furthermore, preincubation with either apamin plus TRAM-34 or paxillin significantly attenuated aspirin vasodilation (p < 0.05). For the first time, we showed that aspirin induced endothelium-dependent vasodilation in mesenteric resistance arteries through the endothelial-derived hyperpolarizing factor (EDHF) and calcium-activated potassium channels. By activating this molecular mechanism, aspirin may lower peripheral vascular resistance and be beneficial in pregnancies complicated by hypertension.

Management of Ischemic Heart Disease in Pregnancy

PURPOSE OF REVIEW

Cardiovascular disease is an escalating cause of maternal morbidity and mortality. Women are at risk for acute myocardial infarction (MI), and more are living with risk factors for ischemic heart disease (IHD). The purpose of this review is to describe the evaluation and management of women at risk for and diagnosed with IHD in pregnancy.

RECENT FINDINGS

Pregnancy can provoke MI which has been estimated as occurring in 1.5-10/100, 000 deliveries or 1/12,400 hospitalizations, with a high inpatient mortality rate of approximately 5-7%. An invasive strategy may or may not be preferred, but fetal radiation exposure is less of a concern in comparison to maternal mortality. Common medications used to treat IHD may be continued successfully during pregnancy and lactation, including aspirin, which has an emerging role in pregnancy to prevent preeclampsia, preterm labor, and maternal mortality. Hemodynamics can be modulated during pregnancy, labor, and postpartum to mitigate risk for acute decompensation in women with IHD. Cardiologists can successfully manage IHD in pregnancy with obstetric partners and should engage women in a lifetime of cardiovascular care.

Prospective longitudinal cohort study of uterine arteries Doppler in singleton pregnancies obtained by IVF/ICSI with oocyte donation or natural conception

STUDY QUESTION

Do uterine arteries Doppler studies show different pulsatility index (UtA-PI) measurements in IVF/ICSI pregnancies with oocyte donation (OD) as compared to natural conceptions?

SUMMARY ANSWER

In IVF/ICSI pregnancies with OD, UtA-PI is reduced by an average of about 40% as compared to pregnancies with natural conception.

WHAT IS KNOWN ALREADY

OD pregnancies present worse pregnancy outcomes as compared to natural conception, particularly for increased incidence of pre-eclampsia (PE). Recent evidence shows that IVF/ICSI pregnancies with frozen blastocyst transfer also present higher prevalence of PE and 15% lower UtA-PI as compared to pregnancies after fresh blastocyst transfers.

STUDY DESIGN, SIZE, DURATION

Prospective, longitudinal matched cohort study performed in the Fetal Medicine and Obstetric Departments of San Raffaele Hospital in Milan, between 2013 and 2018. The analysis is based on 584 Doppler observations collected from 296 women with different method of conception (OD n = 122; natural conception n = 174).

PARTICIPANTS/MATERIALS, SETTING, METHODS

IVF/ICSI viable singleton pregnancies with OD and natural conception control pregnancies matched for BMI and smoking, performing repeated UtA-PI measurements at 11-34 weeks. Miscarriages, abnormalities, twins, significant maternal diseases and other types of ARTs were excluded. Log mean left-right UtA-PI was used for analysis with linear mixed model (LMM) and correction for significant confounders. Pregnancy outcome was also analyzed.

MAIN RESULTS AND THE ROLE OF CHANCE

Participants after OD were older and more frequently nulliparous (mean age: OD 43.4, 95% CI from 42.3 to 44.6; natural conception 35.1, 95% CI from 34.5 to 35.7; P-value < 0.001; nulliparous: OD 96.6%; natural conception 56.2%; P-value < 0.001). Mean pulsatility index was lower in OD (UtA-PI: natural conception 1.22; 95% CI from 1.11 to 1.28; OD 1.04; 95% CI from 0.96 to 1.12; P-value < 0.001). A significant effect of parity, gestational age (GA) modeled with a cubic polynomial and BMI was described in the LMM. The mean Log UtA-PI was on average 37% lower in OD as compared to natural conception pregnancies at LMM (P-value < 0.001). We also found a significant interaction between longitudinal UtA-PI Doppler and GA. Therefore, at 11 weeks' gestation the Log UtA-PI was 42% lower and, at 34 weeks, the differences reduced to 32%. GA at delivery and birth weight were statistically lower in OD group; however, birthweight centile was not statistically different. Preeclampsia was 11-fold more common in the OD group (0.6% and 6.6%, P-value = 0.003). No other significant difference in pregnancy outcome was shown in the study groups (gestational diabetes mellitus, small or large for GA).

LIMITATIONS, REASONS FOR CAUTION

It was not possible to properly match for maternal age and to blind the assessment given the major differences between cohorts; however, we did not find significant within-groups effects related to maternal age. Future research is needed to reassess outcomes and correct them for maternal characteristics (e.g. cardiovascular function).

WIDER IMPLICATIONS OF THE FINDINGS

This finding reproduces our previous discovery of lower UtA-PI in frozen as compared to fresh blastocyst transfer. The vast majority of OD is obtained by the use of cryopreservation. We speculate that increased uterine perfusion may be the physiological response to compensate dysfunctions both in the mother and in the placenta.

STUDY FUNDING/COMPETING INTEREST(S)

This is a non-funded study. The authors do not declare competing interest.

TRIAL REGISTRATION NUMBER

N/A.

Uterine artery Doppler in singleton pregnancies conceived after in-vitro fertilization or intracytoplasmic sperm injection with fresh vs frozen blastocyst transfer: longitudinal cohort study

OBJECTIVE

Pregnancies conceived by frozen blastocyst transfer (FBT) have higher gestational age and weight at birth as compared to those derived by fresh blastocyst transfer. The aim of this study was to evaluate uterine artery pulsatility index (UtA-PI) in pregnancies conceived by in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) techniques using fresh vs cryopreserved blastocysts.

METHODS

This was a prospective longitudinal study of viable singleton IVF/ICSI pregnancies conceived after FBT or fresh blastocyst transfer, that underwent serial ultrasound assessment at San Raffaele Hospital, Milan, Italy at 7-37 gestational weeks. We excluded pregnancies conceived using other assisted reproductive techniques such as egg donation, twin gestation, pregnancy with abnormality and those resulting in miscarriage. Pregnant women underwent ultrasound assessment at 7-10, 11-14, 18-25 and 26-37 weeks' gestation. Mean UtA-PI was measured using Doppler ultrasound according to The Fetal Medicine Foundation criteria. Pregnancy outcomes were recorded. The primary outcome was mean UtA-PI measurement and secondary outcomes were gestational age at birth, birth weight and fetal and maternal complications, including small-for-gestational age (SGA), pre-eclampsia and large-for-gestational age. UtA-PI values were made Gaussian after log₁₀ transformation. Analysis of repeated measures using a multilevel linear mixed model (fixed effects and random effects) was performed. The possible effect of other covariates on UtA-PI Doppler values, including body mass index, SGA and pre-eclampsia, was also evaluated.

RESULTS

A total of 367 IVF/ICSI cycles, comprising 164 with fresh blastocyst transfer and 203 with FBT, were included and a total of 625 observations (median, 2.5 (range, 1-4)) were collected and analyzed. The FBT group had on average 14% lower UtA-PI compared with the fresh-blastocyst-transfer group. In pregnancies with SGA fetuses, UtA-PI was 18% higher compared to pregnancies without, irrespective of the study group. Pregnancies that underwent fresh blastocyst transfer had significantly lower birth-weight centile (43.4 ± 23.3 vs 50.0 ± 23.1; P = 0.007) and a higher rate of SGA (7.9% vs 2.0%; P = 0.008) compared to those that underwent FBT. No significant differences were found between the two groups with respect to gestational age at birth and rates of preterm birth, pre-eclampsia, gestational diabetes mellitus and large-for-gestational age.

CONCLUSION

UtA-PI and the proportion of SGA are lower in IVF/ICSI pregnancies conceived after FBT as compared to fresh blastocyst transfer. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

The effect of low-dose aspirin on the pregnancy rate in frozen-thawed embryo transfer cycles: A randomized clinical trial

Background

The results of previous studies on the effect of low-dose aspirin in frozen-thawed embryo transfer (FET) cycles are limited and controversial.

Objective

To evaluate the effect of low-dose aspirin on the clinical pregnancy in the FET cycles.

Materials and Methods

This study was performed as a randomized clinical trial from May 2018 to February 2019; 128 women who were candidates for the FET were randomly assigned to two groups receiving either 80 mg oral aspirin (n = 64) or no treatment. The primary outcome was clinical pregnancy rate and secondary outcome measures were the implantation rate, miscarriage rate, and endometrial thickness.

Results

The endometrial thickness was lower in patients who received aspirin in comparison to the control group. There were statistically significant differences between the two groups (p = 0.018). Chemical and clinical pregnancy rates and abortion rate was similar in the two groups and there was no statistically significant difference.

Conclusion

The administration of aspirin in FET cycles had no positive effect on the implantation and the chemical and clinical pregnancy rates, which is in accordance with current Cochrane review that does not recommend aspirin administration as a routine in assisted reproductive technology cycles.

The Correlation Between Abnormal Uterine Artery Flow in the First Trimester and Genetic Thrombophilic Alteration: A Prospective Case-Controlled Pilot Study

INTRODUCTION

Evaluation of the first trimester uterine artery flow can predict the development of obstetrical complications. A genotype, making women prone to microthrombi. constitutes the main known susceptibility factor for anomalous development of placenta. Our aim was to study whether polymorphisms of 10 genes leading to blood clotting abnormalities are related to abnormal uterine artery blood flow in the first trimester, and may predict placenta-related diseases.

MATERIAL AND METHODS

In primary analyses we included 19 singleton pregnancies with abnormal blood flow in the uterine arteries during the first trimester of gestation, and 24 matched control with normal flow patterns. All patients were genotyped for sequence variations in F5, F2, F11, MTHFR, SERPINE-1, CYP4V2, SELE, GP6, angiotensinogen (AGT) and fibrinogen gamma (FGG) genes and followed up until delivery.

RESULTS

There were no differences between groups regarding selected sequence variations in any of these genes. The co-occurrence of several polymorphisms in the same patient was also not related to the blood flow patterns in the uterine arteries.

CONCLUSIONS

Although we found certain trends of genetic polymorphisms being related to preeclampsia and fetal growth, we failed to find an association between clotting gene polymorphisms, single or in combination, with the abnormal uterine flow in the first trimester.

Aspirin enhances trophoblast invasion and represses soluble fms-like tyrosine kinase 1 production: a putative mechanism for preventing preeclampsia

OBJECTIVE

Recent studies suggested that prophylactic aspirin prior to 16 weeks of gestation in high-risk patients may reduce the risk of developing preeclampsia; however, the exact mechanism of aspirin's effect on the pathophysiology of preeclampsia is not clear. This study was designed to investigate the effect of aspirin on trophoblast cell function and its effect on soluble fms-like tyrosine kinase 1 (sFlt-1) production to elucidate the preventive mechanisms for preeclampsia.

METHODS AND RESULTS

We used two human trophoblastic cell lines (HTR-8/SVneo and JAR) and freshly isolated cytotrophoblasts from normal and preeclamptic placenta at term to determine the effect of aspirin on trophoblast cell function. Trophoblasts were pretreated with aspirin, and then cell functions and sFlt-1 expression were assessed. Our results showed that aspirin promoted trophoblast invasion not only in HTR-8/SVneo and JAR cells, but also in isolated cytotrophoblasts. sFlt-1 production was repressed by aspirin in a dose-dependent manner. By adding Flt-1 recombinant protein, the trophoblast invasion ability was inhibited in HTR-8/SVneo cells, which was reversed by Flt-1 small interfering ribonucleic acid knockdown. In addition, metalloproteinase 2/9 expression and activity were activated by aspirin but inhibited by sFlt-1. Aspirin also downregulated Akt phosphorylation, and trophoblast invasiveness was facilitated under Akt inhibitor treatment.

CONCLUSION

Aspirin enhances cell invasiveness and inhibits sFlt-1 production in trophoblasts. Moreover, sFlt-1 itself also inhibits trophoblast invasion. Our novel findings suggest that the preeclampsia prevention effect of aspirin may be exerted through these two mechanisms.

A Pilot Randomized Trial Comparing the Effects of 80 versus 160 mg of Aspirin on Midtrimester Uterine Artery Pulsatility Index in Women with a History of Preeclampsia

OBJECTIVE

To compare the effects of 80 mg and 160 mg of aspirin, initiated in the first trimester of pregnancy, on mid-trimester uterine artery pulsatility index (UtA-PI) in women with a history of preeclampsia.

METHODS

We performed a pilot double-blind randomized controlled trial. Pregnant women with a history of preeclampsia were recruited between 10^0/7 and 13^6/7 weeks gestation and randomly assigned to take either 80 or 160 mg of aspirin daily at bedtime from randomization to 35^6/7 weeks gestation. The primary outcome was mean UtA-PI at 22-24 weeks. Secondary outcomes included the rate of fetal growth restriction and preeclampsia, stratified as term (≥37 weeks), preterm (<37 weeks), and early-onset (<34 weeks) preeclampsia.

RESULTS

A total of 107 participants were randomized, including 41 (38%) with a history of preterm preeclampsia and 16 (15%) with a history of early-onset preeclampsia. We observed no significant difference in mean UtA-PI at 22-24 weeks between the 2 groups (0.97; 95% CI 0.88-1.05 vs. 0.97; 95% CI 0.88-1.07, P = 0.9). The rates of fetal growth restriction (8% vs. 2%; P = 0.20); preeclampsia (12% vs. 15%; P = 0.78), preterm preeclampsia (4% vs. 2%; P = 0.56), and early-onset preeclampsia (0% vs. 2%; P = 0.52) were similar in both groups. No serious adverse events associated with the study treatment were reported.

CONCLUSION

We observed no significant difference in UtA-PI between the two doses of aspirin, but we observed low rates of fetal growth restriction and preterm and early-onset preeclampsia (all less than 5%). The benefits of aspirin for the prevention of preterm preeclampsia is probably not related to the improvement of deep placentation alone.

Impact of low-dose aspirin on adverse perinatal outcome: meta-analysis and meta-regression

OBJECTIVE

To perform a meta-analysis and meta-regression of randomized controlled trials (RCTs) to evaluate the impact of low-dose aspirin (LDA) on perinatal outcome, independent of its effect on pre-eclampsia (PE), preterm birth and low birth weight.

METHODS

An electronic search of EMBASE, PubMed, CENTRAL, PROSPERO and Google Scholar databases was performed to identify RCTs assessing the impact of LDA in pregnancy, published in English prior to May 2019, which reported perinatal outcomes of interest (placental abruption, delivery mode, low 5-min Apgar score, neonatal acidosis, neonatal intensive care unit admission, periventricular hemorrhage and perinatal death). Risk ratios (RR) and 95% CI were calculated and pooled for analysis. Analysis was stratified according to gestational age at commencement of treatment (≤ 16 weeks vs > 16 weeks) and subgroup analysis was performed to assess the impact of aspirin dose (< 100 mg vs ≥ 100 mg). Meta-regression was used to assess the impact of LDA on perinatal outcome, independent of the reduction in PE, preterm birth and low birth weight.

RESULTS

Forty studies involving 34 807 participants were included. When LDA was commenced ≤ 16 weeks' gestation, it was associated with a significant reduction in the risk of perinatal death (RR, 0.47; 95% CI, 0.25-0.88; P = 0.02; number needed to treat, 92); however, this risk reduction was only seen when a daily dose of ≥ 100 mg was administered. If commenced > 16 weeks' gestation, LDA was associated with a significant reduction in 5-min Apgar score < 7 (RR, 0.75; 95% CI, 0.58-0.96; P = 0.02) and periventricular hemorrhage (RR, 0.68; 95% CI, 0.47-0.99; P = 0.04), but a trend towards an increase in the risk of placental abruption (RR, 1.20; 95% CI, 1.00-1.46; P = 0.06) was also noted. LDA was not associated with any significant increase in adverse events if commenced ≤ 16 weeks gestation. LDA had no effect on delivery mode, irrespective of the gestational age at which it was started. Meta-regression confirmed that the effect of LDA on perinatal death, when treatment was started ≤ 16 weeks' gestation, was independent of any reduction in the rate of PE and preterm birth.

CONCLUSION

LDA improves some important perinatal outcomes, without increasing adverse events such as placental abruption or periventricular hemorrhage, and its utility, if commenced prior to 16 weeks' gestation, may be considered in a wider context beyond the prevention of PE or fetal growth restriction. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Molecular Targets of Aspirin and Prevention of Preeclampsia and Their Potential Association with Circulating Extracellular Vesicles during Pregnancy

Uncomplicated healthy pregnancy is the outcome of successful fertilization, implantation of embryos, trophoblast development and adequate placentation. Any deviation in these cascades of events may lead to complicated pregnancies such as preeclampsia (PE). The current incidence of PE is 2–8% in all pregnancies worldwide, leading to high maternal as well as perinatal mortality and morbidity rates. A number of randomized controlled clinical trials observed the association between low dose aspirin (LDA) treatment in early gestational age and significant reduction of early onset of PE in high-risk pregnant women. However, a substantial knowledge gap exists in identifying the particular mechanism of action of aspirin on placental function. It is already established that the placental-derived exosomes (PdE) are present in the maternal circulation from 6 weeks of gestation, and exosomes contain bioactive molecules such as proteins, lipids and RNA that are a “fingerprint” of their originating cells. Interestingly, levels of exosomes are higher in PE compared to normal pregnancies, and changes in the level of PdE during the first trimester may be used to classify women at risk for developing PE. The aim of this review is to discuss the mechanisms of action of LDA on placental and maternal physiological systems including the role of PdE in these phenomena. This review article will contribute to the in-depth understanding of LDA-induced PE prevention.

Effect of low-dose aspirin on the development of ovarian hyperstimulation syndrome and outcomes of assisted reproductive techniques in the women with PCOS, a randomized double-blinded clinical trial

OBJECTIVE

Ovarian hyperstimulation syndrome (OHSS) is a major complication of assisted reproductive technologies (ART). Polycystic ovary syndrome (PCOS) is a risk factor for OHSS. The aim of this randomized clinical trial (RCT) was to study the effect of low-dose aspirin (LDA) on the development of OHSS and ART outcomes in PCOS during ART.

MATERIALS AND METHODS

This double-blinded placebo controlled RCT was performed on 232 PCOS infertile women in their first ART cycles during 2010-2016. LDA and placebo capsules were prepared, packed and specified by code numbers in similar shapes. One package was given to every woman and asked to take one capsule/day since the 21st day of her cycle prior to the gonadotropin stimulation. Gonadotropin releasing hormone agonist long protocol and triggering by human chorionic gonadotropin were used. Development of moderate to severe OHSS and their ART outcomes were documented then the codes were broken and data analyzed. Chi-square and Mann-Whitney U tests were used for the statistical analyses.

RESULTS

Eighteen cases that did not follow the study design were excluded. 214 cycles remained for the final analyses with 109 cases in LDA and 105 in the placebo group. Rate of the moderate to severe OHSS in LDA group was 34.9% compared to 30.5% in placebo group (P = 0.494). Fertilization rate was 71.8% vs 65.1% (P = <0.001) and the mean number of grade III embryos were 3.28 ± 3.53 vs 1.46 ± 1.42 (P = 0.014) in LDA and placebo groups, respectively. The mean number of the oocytes in different grades, total and frozen embryos also implantation and clinical pregnancy rates were not different between the groups.

CONCLUSION

Moderate to Severe OHSS was not decreased but fertilization rate and the mean number of poor quality embryos were increased in LDA arm.

REGISTRATION NUMBER

IRCT 201105216541N1.

Aspirin causes endothelium-dependent vasodilation of resistance arteries from non-gravid and gravid rats

OBJECTIVE

The objective of this study was to understand the effect of acetylsalicylic acid (aspirin) on resistance arteries from mesentery and uterus. During pregnancy, the uterine vasculature undergoes consistent growth to provide sufficient uteroplacental blood flow, a process whose failure is associated with pregnancy complications characterized by high uterine vascular resistance.

METHODS

Uterine arcuate (UA) and mesenteric arteries (MA; diameter <300 µm) isolated from non-gravid, mid-gravid (day 14), and late-gravid rats (day 20) were exposed to aspirin (10^-12 to 10^-5 M). Further, in UA from late-gravid rats, aspirin was evaluated in presence of inhibitors of nitric oxide synthases, cyclooxygenase, cyclic nucleotides (cAMP, cGMP) and BK channels, and also on endothelium-denuded vessels.

RESULTS

Aspirin dilated both UA and MA in a dose dependent manner. Pregnancy increased aspirin vasodilation in MA and UA from mid-gravid rats, an effect that was reduced in vessels from late gravid animals at concentrations >10^-7 M. Further, uterine vasodilation was significantly reduced when the endothelium was removed (p < 0.001), and by inhibitors of nitric oxide synthase (p < 0.001), cyclooxygenase synthase (p < 0.05), cyclic nucleotides cGMP/cAMP and BK channels.

CONCLUSION

This is the first study to show a direct vasodilatory effect of aspirin on rat uterine artery that is mediated by a combination of cellular - primarily endothelial - mechanisms. Our results in UA suggest that the use of aspirin may be effective in enhancing uteroplacental blood flow, while its vasodilation effect on MA may lower peripheral resistance.

Association of intrauterine exposure to aspirin and blood pressure at 7 years of age: a secondary analysis

OBJECTIVE

To examine whether maternal aspirin use during pregnancy is associated with childhood blood pressure.

DESIGN/SETTING

A secondary analysis of the Collaborative Perinatal Project, a prospective cohort study including 12 US academic medical centres between 1959 and 1976.

POPULATION

Singleton births among women with detailed medication information.

METHODS

We carried out linear and multivariate logistic regression analysis to assess the associations between maternal aspirin exposure and childhood blood pressure at age 7 years.

MAIN OUTCOME MEASURES

Offspring blood pressure at age 7 years.

RESULTS

A total of 15 793 women were exposed to aspirin 4 weeks before the last menstrual period or during pregnancy. In utero aspirin exposure may be associated with an 11% (95% CI 0.85- 0.93) and a 20% (95% CI 0.76-0.84) reduced risk of having high systolic blood pressure (SBP) and diastolic blood pressure (DBP) at 7 years of age, and a mean decrease of 0.62 mmHg for SBP and 1.04 mmHg for DBP at 7 years of age. Compared with children born to mothers without aspirin exposure, those whose mothers were exposed to aspirin for at least 7 days during pregnancy had approximately 10% and 27% reduced risk of high SBP and DBP, respectively, and a mean reduction of 0.61 and 1.27 mmHg in SBP and DBP at 7 years of age. The earlier the aspirin exposure occurred during pregnancy, the lower the risk of childhood high blood pressure.

CONCLUSION

In utero exposure to aspirin may have long-term benefits for childhood blood pressure.

TWEETABLE ABSTRACT

Maternal aspirin exposure might decrease the risk of childhood blood pressure.

A prophylactic low-dose aspirin earlier than 12 weeks until delivery should be considered to prevent preeclampsia

Clinical trials and meta-analyses have demonstrated that low-dose aspirin can reduce the risk of preeclampsia and fetal growth restriction in high-risk pregnant women. Current obstetric guidelines recommend that the administration of low-dose aspirin to prevent preeclampsia be initiated after 12 weeks' gestation. This starting time was chosen to minimize possible risks of maternal bleeding and fetal anomalies. However, evidence from reproductive medicine, where low-dose aspirin is commonly recommended to use before and in early pregnancy, as well as existing literature, does not support these concerns. On the other hand, defective placentation resulting in a subsequent ischemic placenta is considered as the starting point of preeclampsia. Low-dose aspirin initiated in early pregnancy can balance the levels of thromboxane A₂ and prostacyclin and maintain adequate uteroplacental blood flow and, therefore, improve placentation. Thus, an initiation of low-dose aspirin earlier than 12 weeks can be considered. Meanwhile, evidence shows that low-dose aspirin can improve maternal vascular endothelial function without increasing the risks of adverse maternal and perinatal outcomes. Therefore, it appears safe to use low-dose aspirin as a prophylactic until delivery.

Impact of aspirin on trophoblastic invasion in women with abnormal uterine artery Doppler at 11-14 weeks: a randomized controlled study

OBJECTIVE

Defective trophoblastic invasion is a key feature in many cases of pre-eclampsia (PE). Uterine artery (UtA) Doppler is a validated non-invasive proxy for trophoblastic invasion. The aim of this study was to explore whether low-dose aspirin, administered from the first trimester, improves trophoblastic invasion, evaluated by UtA Doppler during the second and third trimesters in women defined as high risk by abnormal first-trimester UtA Doppler.

METHODS

This randomized Phase-II study had a triple-blind, parallel-arm, controlled design. Singleton pregnancies with abnormal mean UtA Doppler at 11-14 weeks and absence of other major risk factors for PE received 150 mg extended-release aspirin or identical-appearing placebo tablets from study inclusion to 28 weeks. Main outcome measure was UtA pulsatility index (PI) at 28 weeks' gestation. Secondary outcomes included frequency of development of PE and growth restriction/small-for-gestational age (SGA).

RESULTS

A total of 155 women completed the follow-up and were analyzed. No difference in mean UtA-PI was found between women in the aspirin and placebo groups at 28 weeks (mean UtA-PI Z-score (mean ± SD), 0.99 ± 1.48 vs 0.85 ± 1.25; P = 0.52). Seven women developed PE: four (5%) in the aspirin group and three (4%) in the placebo group. There was a trend toward lower incidence of SGA in the aspirin group (8.8% vs 17.3%; P = 0.11).

CONCLUSION

In women with defective trophoblastic invasion, as reflected by abnormal UtA Doppler, low-dose aspirin started in the first trimester does not have a significant effect on UtA impedance as pregnancy progresses; however, the study was underpowered to detect potential small effects . Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Antiplatelet therapy before or after 16 weeks' gestation for preventing preeclampsia: an individual participant data meta-analysis

BACKGROUND

The optimum time for commencing antiplatelet therapy for the prevention of preeclampsia and its complications is unclear. Aggregate data meta-analyses suggest that aspirin is more effective if given prior to 16 weeks' gestation, but data are limited because of an inability to place women in the correct gestational age subgroup from relevant trials.

OBJECTIVE

The objective of the study was to use the large existing individual participant data set from the Perinatal Antiplatelet Review of International Studies Collaboration to assess whether the treatment effects of antiplatelet agents on preeclampsia and its complications vary based on whether treatment is started before or after 16 weeks' gestation.

STUDY DESIGN

A meta-analysis of individual participant data including 32,217 women and 32,819 babies recruited to 31 randomized trials comparing low-dose aspirin or other antiplatelet agents with placebo or no treatment for the prevention of preeclampsia has been published previously. Using this existing data set, we performed a prespecified subgroup analysis based on gestation at randomization to antiplatelet agents before 16 weeks, compared with at or after 16 weeks, for 4 of the main outcomes prespecified in the Perinatal Antiplatelet Review of International Studies protocol: preeclampsia, death of baby, preterm birth before 34 weeks, and small-for-gestational-age baby. Individual participant data for the subgroups were combined in a meta-analysis using RevMan software. Heterogeneity was assessed with the I² statistic. The χ² test for interaction was used to assess statistically significant (P < .05) differences in treatment effect between subgroups.

RESULTS

There was no significant difference in the effects of antiplatelet therapy for women randomized before 16 weeks' gestation compared with those randomized at or after 16 weeks for any of the 4 prespecified outcomes: preeclampsia, relative risk, 0.90, (95% confidence interval, 0.79-1.03; 17 trials, 9241 women) for <16 weeks and relative risk, 0.90 (95% confidence interval, 0.83-0.98; 22 trials, 21,429 women) for ≥16 weeks (interaction test, P = .98); death of baby, relative risk, 0.89 (95% confidence interval, 0.73-1.09; 15 trials, 8626 women) for <16 weeks and relative risk, 0.92 (95% confidence interval, 0.79-1.07; 21 trials, 22,336 women) for ≥16 weeks (interaction test, P = .80); preterm birth prior to 34 weeks, relative risk, 0.90 (95% confidence interval, 0.77-1.04; 19 trials, 9155 women) for <16 weeks and relative risk, 0.91 (95% confidence interval, 0.82-1.00; 25 trials, 22,117 women) for ≥16 weeks (interaction test, P = .91); and small-for-gestational-age baby, relative risk, 0.76 (95% confidence interval, 0.61-0.94; 13 trials, 6393 women) for <16 weeks and relative risk, 0.95 (95% confidence interval, 0.84-1.08; 18 trials, 14,996 women) for ≥16 weeks (interaction test, P = .08).

CONCLUSION

The effect of low-dose aspirin and other antiplatelet agents on preeclampsia and its complications is consistent, regardless of whether treatment is started before or after 16 weeks' gestation. Women at an increased risk of preeclampsia should be offered antiplatelet therapy, regardless of whether they are first seen before or after 16 weeks' gestation.

Could empirical low-dose-aspirin administration during IVF cycle affect both the oocytes and embryos quality via COX 1-2 activity inhibition?

PURPOSE

To compare qualitative and quantitative ovarian response in idiopathic infertile women treated with low-dose-aspirin (LDA) during in-vitro-fertilization (IVF) cycles (pl) versus untreated ones.

METHODS

We conducted an observational-cohort-study on normo-responders patients aged between 25 and 45,years referred to Assisted-Reproductive Unit --University of Padua--in order to evaluate the ovarian response effects (both qualitative and quantitative) after LDA administration. In detail we aim to assess if LDA administration could improve ovarian response, reducing the gonadotropin administration, and if its administration could increase the amount of follicles greater than 16 mm at pick-up, the amount and quality of oocytes retrieved, the amount and quality of embryos, the chance to achieve a pregnancy and to carry it on.

RESULTS

One hundred six LDA-treated patients (Group-A) and 100 not-treated ones (Group-B) were homogeneous for age and BMI. The Group-A, compared to Group-B, showed higher gonadotropin request, higher number of ovarian follicles at pick-up, more follicles bigger than 16 mm in diameter and more retrieved oocytes (despite higher number of immature and at germinal vesicle stage oocytes) but lower quality of obtained embryos. The comparison between two Groups in term of retrieved oocytes /number of follicles, mature oocytes/retrieved oocytes, fertilized oocytes/mature oocytes and good embryos quality/mature oocytes showed a strongly advantageous ratio for Group-B. For each considered outcome, we found a dose-related effect.

CONCLUSIONS

It is mandatory to define which patients could benefit from LDA administration and the adequate timing to administer it since the empirical administration could negatively affect both oocyte and embryo quality during IVF cycles.

Obstetric Pharmacokinetic Dosing Studies are Urgently Needed

Use of pharmacotherapy during pregnancy is common and increasing. Physiologic changes during pregnancy may significantly alter the overall systemic drug exposure, necessitating dose changes. A search of PubMed for pharmacokinetic clinical trials showed 494 publications during pregnancy out of 35,921 total pharmacokinetic published studies (1.29%), from the late 1960s through August 31, 2013. Closer examination of pharmacokinetic studies in pregnant women published since 2008 (81 studies) revealed that about a third of the trials were for treatment of acute labor and delivery issues, a third included studies of infectious disease treatment during pregnancy, and the remaining third were for varied ante-partum indications. Approximately, two-thirds of these recent studies were primarily funded by government agencies worldwide, one-quarter were supported by private non-profit foundations or combinations of government and private funding, and slightly <10% were supported by pharmaceutical industry. As highlighted in this review, vast gaps exist in pharmacology information and evidence for appropriate dosing of medications in pregnant women. This lack of knowledge and understanding of drug disposition throughout pregnancy place both the mother and the fetus at risk for avoidable therapeutic misadventures - suboptimal efficacy or excess toxicity - with medication use in pregnancy. Increased efforts to perform and support obstetric dosing and pharmacokinetic studies are greatly needed.

Prevention of perinatal death and adverse perinatal outcome using low-dose aspirin: a meta-analysis

OBJECTIVE

To compare early vs late administration of low-dose aspirin on the risk of perinatal death and adverse perinatal outcome.

METHODS

Databases were searched for keywords related to aspirin and pregnancy. Only randomized controlled trials that evaluated the prophylactic use of low-dose aspirin (50-150 mg/day) during pregnancy were included. The primary outcome combined fetal and neonatal death. Pooled relative risks (RR) with their 95% CIs were compared according to gestational age at initiation of low-dose aspirin (≤ 16 vs > 16 weeks of gestation).

RESULTS

Out of 8377 citations, 42 studies (27 222 women) were included. Inclusion criteria were risk factors for pre-eclampsia, including: nulliparity, multiple pregnancy, chronic hypertension, cardiovascular or endocrine disease, prior gestational hypertension or fetal growth restriction, and/or abnormal uterine artery Doppler. When compared with controls, low-dose aspirin started at ≤ 16 weeks' gestation compared with low-dose aspirin started at >16 weeks' gestation was associated with a greater reduction of perinatal death (RR = 0.41 (95% CI, 0.19-0.92) vs 0.93 (95% CI, 0.73-1.19), P = 0.02), pre-eclampsia (RR = 0.47 (95% CI, 0.36-0.62) vs 0.78 (95% CI, 0.61-0.99), P < 0.01), severe pre-eclampsia (RR = 0.18 (95% CI, 0.08-0.41) vs 0.65 (95% CI, 0.40-1.07), P < 0.01), fetal growth restriction (RR = 0.46 (95% CI, 0.33-0.64) vs 0.98 (95% CI, 0.88-1.08), P < 0.001) and preterm birth (RR = 0.35 (95% CI, 0.22-0.57) vs 0.90 (95% CI, 0.83-0.97), P < 0.001).

CONCLUSION

Low-dose aspirin initiated at ≤ 16 weeks of gestation is associated with a greater reduction of perinatal death and other adverse perinatal outcomes than when initiated at >16 weeks.

Low-dose aspirin for in vitro fertilization or intracytoplasmic sperm injection: a systematic review and a meta-analysis of the literature

BACKGROUND

It was hypothesized that low-dose aspirin could improve implantation rates in subsequent pregnancies in women undergoing in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI). Previous studies have shown inconclusive results or focused on surrogate endpoints. We therefore conducted a systematic review and meta-analysis of the literature investigating the effect of low-dose aspirin on hard outcomes, including live birth rate, pregnancy rate and miscarriage.

METHODS

MEDLINE and EMBASE databases were searched up to November 2011. Randomized controlled trials comparing low-dose aspirin with placebo/no treatment in IVF/ICSI women were included. Pooled odds ratios (ORs) and 95%confidence intervals (CIs) were calculated.

RESULTS

Seventeen studies with 6403 patients were included. The use of aspirin did not improve live birth pregnancy rate compared with placebo or no treatment (1.08; 95% CI, 0.90, 1.29). Pregnancy rates were significantly increased in patients randomized to low-dose aspirin (OR, 1.19; 95% CI, 1.01, 1.39), but miscarriage rates were not (OR, 1.18; 95% CI, 0.82, 1.68). Results of sensitivity analyses including high-quality studies did not show statistically significant differences in all considered endpoints.

CONCLUSIONS

The results of this study do not show a substantial efficacy of aspirin inwomen undergoing IVF/ICSI and do not support the use of low-dose aspirin to improve the success of IVF/ICSI in terms of pregnancy outcomes. Further high-quality studies evaluating the possible efficacy of aspirin in selected groups of patients are warranted.

ASPIRIN ADMINISTRATION FOR PREVENTION OF ADVERSE PREGNANCY OUTCOMES

The prophylactic use of low-dose aspirin for prevention of preeclampsia has been an important research question in obstetrics for the last three decades. In 1979, Crandon and Isherwood observed that nulliparous women who had taken aspirin regularly during pregnancy were less likely to have preeclampsia than women who did not. In 1985, Beaufils et al published the first randomized trial suggesting that 150 mg aspirin and 300 mg dipyridamole daily from 3 months’ gestation onwards decreased the risk of preeclampsia, fetal growth restriction and stillbirth in high-risk women. Subsequently, more than 50 trials have been carried out throughout the world and a meta-analysis of these studies reported that the administration of low-dose aspirin in high-risk pregnancies is associated with a decrease in the rate of preeclampsia by approximately 10%. Consequently, several national professional bodies recommend that high-risk pregnancies should be treated with aspirin (50–150 mg daily).

Persistence of increased uterine artery resistance in the third trimester and pregnancy outcome

OBJECTIVE

To evaluate whether the persistence of abnormal findings in the third trimester following increased uterine artery (UtA) resistance in the second trimester is related to adverse pregnancy outcome.

METHODS

Low-risk nulliparous women with increased UtA mean pulsatility index (PI) at 20-22 weeks underwent repeat Doppler interrogation at 26-28 weeks and were divided into two groups: those with persistently abnormal Doppler and those with normalized UtA findings. Pregnancy outcome was noted for all patients and compared with that of 104 controls.

RESULTS

We examined 104 women with increased UtA resistance in the second trimester and in 62 (59.6%) cases the abnormal uteroplacental Doppler findings persisted to 26-28 weeks. Compared with controls and with patients with normalized Doppler at the third-trimester scan, patients with persistently abnormal Doppler results had a significantly higher risk of pre-eclampsia (10/62 vs. 1/104, P = 0.002 and 10/62 vs. 1/42, P = 0.047, respectively), small-for-gestational age (SGA) fetus (20/62 vs. 1/104, P < 0.001 and 20/62 vs. 4/42; P = 0.007, respectively) and admission of the infant to a neonatal intensive care unit (16/62 vs. 4/104; P < 0.001 and 16/62 vs. 1/42; P < 0.001, respectively). Compared with controls, cases with normalization had an increased risk of SGA (4/42 vs. 1/104, P = 0.03), but there were no significant differences for the other outcome measures.

CONCLUSIONS

In low-risk nulliparous women with increased UtA resistance in the second trimester, the persistence of abnormal Doppler findings at 26-28 weeks is associated with an increased risk of obstetric complications when compared with both controls and patients with third-trimester Doppler normalization.