The cardiac-fetal-placental unit: fetal umbilical vein flow rate is linked to the maternal cardiac profile in fetal growth restriction

Maternal oxygen inhalation affects the fetal hemodynamic in low-risk with uncomplicated late pregnancy

BACKGROUND

Maternal oxygen inhalation during labor has not been shown to provide significant benefits to newborns. However, its impact on fetal hemodynamics in late pregnancy remains uncertain.

OBJECTIVE

This study aimed to investigate the association between maternal oxygen inhalation in the late trimester and changes in fetal hemodynamics. Specifically, we assessed the short-term effects of maternal oxygen administration on fetal Doppler parameters and evaluated whether this practice has potential benefits or risks for the fetus.

STUDY DESIGN

These retrospective data were obtained from singleton pregnancies who underwent a after 32+0 weeks prenatal ultrasound examination between January 2022 and December 2022. Participants were categorized into oxygen inhalation and non-oxygen inhalation groups. Oxygen inhalation was administered based on maternal request, primarily due to concerns about hypoxia from prolonged mask use during the COVID-19 pandemic, rather than clinical indication. Our study analysis was performed in August 2023. In oxygen inhalation group, pregnant women received oxygen inhalation with 3 L/min for 30 min by nasal cannula, and before went to department of ultrasound for sonographic assessment within 1 h. The CPR and PPI were predefined as primary outcomes prior to analysis. Each woman was recorded Doppler index and calculated placental pulsatility index (PPI) and cerebroplacental ratio (CPR). Moreover, fetal cardiac function was assessed within pulsed Doppler or M-mode.

MAIN OUTCOME

The primary outcome presented higher PPI, lower CPR, and lower birth weight for the exposure maternal oxygen inhalation group, compare to non-oxygen inhalation group.

RESULTS

A total of 104 singleton pregnancies were included in the final analysis (oxygen inhalation group: n = 48). No significant differences were observed in the resistance indices of the uterine arteries, umbilical arteries, middle cerebral arteries, descending aorta, ductus venosus, or umbilical vein. However, variations were noted in the oxygen inhalation group. Notably, indices with higher sensitivity for predicting adverse outcomes demonstrated significant differences between groups: PPI was higher in the oxygen inhalation group compared to the non-oxygen inhalation group (0.81 ± 0.12 vs. 0.76 ± 0.11, p < .05), while CPR was also lower in the oxygen inhalation group (1.98 ± 0.56 vs. 2.28 ± 0.70, p < .05). Additionally, birth weight was significantly lower in the oxygen inhalation group compared to the non-oxygen inhalation group (2983.78 ± 468.18 g vs. 3178.41 ± 477.59 g, p < .05).

CONCLUSION

Our study found that brief maternal oxygen inhalation in the third trimester was associated with significant changes in fetal hemodynamics, specifically higher PPI and lower CPR. Both of these indices are sensitive markers of unfavorable prenatal outcomes, indicating that maternal oxygen inhalation may adversely affect fetal health. These findings underscore the importance of carefully evaluating the use of oxygen inhalation in pregnant women, especially those in high-risk pregnancies. Additionally, monitoring Doppler indices before and after oxygen administration may help assess fetal well-being and guide clinical decision-making in these situations.

Cardiac output-guided maternal positioning in pregnancy-- can it improve outcomes?

Chronic and recurrent obstruction of the inferior vena cava by the uterus during the second half of pregnancy are theorized to contribute to the causation of preeclampsia, fetal growth restriction, preterm birth, dysfunctional labor and postpartum uterine atony. Such obstruction is hypothesized to be asymptomatic for the mother but can be detected and minimized by non-invasive continuous trending of maternal cardiac output, because positional decreases in cardiac output can serve as a warning signal of obstruction of venous return. Injury may be caused by 1) decreased cardiac output, 2) increased uterine venous and intervillous pressures and 3) decreased intervillous perfusion. Wide variations in intervillous oxygen tension may be more harmful than low but stable oxygen tension. Clinical examples of asymptomatic but dramatic positional changes in maternal cardiac output in hospitalized patients are shown. Further research should begin with laboring patients, since cardiac output changes dramatically over time and with position during labor.

The role of umbilical vein blood flow assessment in the prediction of fetal growth velocity and adverse outcome: a prospective observational cohort study

BACKGROUND

Identifying fetal growth restriction and distinguishing it from a constitutionally small fetus can be challenging. The umbilical vein blood flow is a surrogate parameter of the amount of oxygen and nutrients delivered to the fetus, providing valuable insights about the function of the placenta. Nevertheless, currently, this parameter is not used in the diagnosis and management of fetal growth restriction.

OBJECTIVE

To evaluate the umbilical vein blood flow and fetal growth velocity in small for gestational age fetuses and in fetal growth restriction, and to evaluate their capacity to predict adverse perinatal outcome and iatrogenic preterm birth. Secondly, to assess the correlation between umbilical vein blood flow and fetal growth velocity.

STUDY DESIGN

This was a prospective multicentric observational cohort study of women with a diagnosis of small for gestational age or fetal growth restriction in which fetal biometry and Doppler assessment, including umbilical vein blood flow measurement, were performed. The fetal growth velocity was derived from the difference between the estimated fetal weight calculated in 2 consecutive sonographic evaluations. The pregnancies were followed until delivery. Between-group differences were evaluated, and Pearson or Spearman correlation coefficients were reported to assess the relationship between variables of interest. Optimal cutoffs on the resulting receiver operating characteristic curve were determined and used to predict the outcomes of interest. Simple and multiple logistic regression models were estimated using umbilical vein blood flow and fetal growth velocity to predict adverse perinatal outcomes and iatrogenic preterm birth.

RESULTS

The study population included 64 small for gestational age and 58 growth restricted fetuses. When compared to reference ranges, small for gestational age fetuses had significantly lower fetal growth velocity and umbilical vein blood flow (P<.001). When compared to small for gestational age, fetuses with growth restriction had lower umbilical vein blood flow (P<.001), umbilical vein blood flow corrected for estimated fetal weight and abdominal circumference (P<.01 and P<.001), and fetal growth velocity (P<.001). Fetal growth velocity was positively correlated with umbilical vein blood flow (r=0.46, P<.001). The multivariable logistic regression analyses showed that, after adjusting for diagnosis of fetal growth restriction, umbilical vein blood flow ≤0.65 multiple of the median (adjusted odds ratio [aOR] 3.5; 95% confidence interval [CI] 1.0-11.8) and fetal growth velocity ≤0.63 multiple of the median (adjusted odds ratio 3.0, 95% CI 1.2-7.9) were associated with adverse perinatal outcome. Furthermore, when accounting for fetal growth restriction diagnosis, umbilical vein blood flow ≤0.60 multiple of the median (adjusted odds ratio 5.2, 95% CI 1.7-15.9), and fetal growth velocity ≤0.63 multiple of the median (adjusted odds ratio 3.6, 95% CI 1.1-12.6) were significant predictors of iatrogenic preterm birth.

CONCLUSION

Umbilical vein blood flow could play a role to identify fetuses with fetal growth restriction and to predict fetal growth at the subsequent biometric evaluation. We found a significant correlation between umbilical vein blood flow and fetal growth. Umbilical vein blood flow and fetal growth velocity are independent predictors of iatrogenic preterm birth and adverse perinatal outcome in a population of small fetuses, regardless of the Delphi consensus criteria. These results support future study on the predictive value of this parameter in fetuses with a suspected fetal growth restriction.

Maternal Hemodynamics from Preconception to Delivery: Research and Potential Diagnostic and Therapeutic Implications: Position Statement by Italian Association of Preeclampsia and Italian Society of Perinatal Medicine

OBJECTIVE

 The Italian Association of Preeclampsia (AIPE) and the Italian Society of Perinatal Medicine (SIMP) developed clinical questions on maternal hemodynamics state of the art.

STUDY DESIGN

 AIPE and SIMP experts were divided in small groups and were invited to propose an overview of the existing literature on specific topics related to the clinical questions proposed, developing, wherever possible, clinical and/or research recommendations based on available evidence, expert opinion, and clinical importance. Draft recommendations with a clinical rationale were submitted to 8th AIPE and SIMP Consensus Expert Panel for consideration and approval, with at least 75% agreement required for individual recommendations to be included in the final version.

RESULTS

 More and more evidence in literature underlines the relationship between maternal and fetal hemodynamics, as well as the relationship between maternal cardiovascular profile and fetal-maternal adverse outcomes such as fetal growth restriction and hypertensive disorders of pregnancy. Experts agreed on proposing a classification of pregnancy hypertension, complications, and cardiovascular states based on three different hemodynamic profiles depending on total peripheral vascular resistance values: hypodynamic (>1,300 dynes·s·cm-5), normo-dynamic, and hyperdynamic (<800 dynes·s·cm-5) circulation. This differentiation implies different therapeutical strategies, based drugs' characteristics, and maternal cardiovascular profile. Finally, the cardiovascular characteristics of the women may be useful for a rational approach to an appropriate follow-up, due to the increased cardiovascular risk later in life.

CONCLUSION

 Although the evidence might not be conclusive, given the lack of large randomized trials, maternal hemodynamics might have great importance in helping clinicians in understanding the pathophysiology and chose a rational treatment of patients with or at risk for pregnancy complications.

KEY POINTS

· Altered maternal hemodynamics is associated to fetal growth restriction.. · Altered maternal hemodynamics is associated to complicated hypertensive disorders of pregnancy.. · Maternal hemodynamics might help choosing a rational treatment during hypertensive disorders..

Value of foetal umbilical vein standardised blood flow volume in predicting weight gain in the third trimester: a prospective case-cohort study

Objective

This study aims to establish a prediction model of foetal umbilical vein standardised blood flow volume (sQuv) on estimated foetal weight (EFW) in the third trimester.

Methods

A case-cohort study involving 200 eligible normal foetuses was conducted at the Ultrasound Department of Longquanyi District of Maternity and Child Healthcare Hospital between June 1, 2020 and December 31, 2021. Ultrasound measurements were taken at two separate intervals to assess EFW and the rate of EFW (rEFW) [first: between 28 w and 33 w6d of gestational age (GA); second: after 4-6 weeks]. Umbilical vein blood flow volume (Quv) and sQuv (normalised with EFW) were calculated only during the initial measurement. Using general linear regression, a prediction model for EFW based on GA and sQuv was developed, with the gestational week employed as a calibration scalar and validated using linear regression cross-validation.

Results

In the third trimester, EFW exhibited significant correlations with GA, abdominal circumference (AC), head circumference (HC) and Quv (all ρ > 0.6, P < 0.001). Furthermore, the rEFW showed significant correlations with Quv and sQuv (all ρ > 0.6, P < 0.001). A linear regression equation was established using a general linear regression model: rEFW = 0.32689 × sQuv. Additionally, a foetal weight prediction model (EFW = -2,554.6770 + 0.9655 × sQuv + 129.6916 × GA) was established using sQuv. The above two formulas were cross-validated by intra-group linear regression and proved to be of good efficacy.

Conclusions

In the third trimester, EFW displayed significant correlations with GA, AC, HC and Quv. Additionally, the rEFW exhibited significant correlations with Quv and sQuv. The sQuv during the third trimester has predictive value for foetal weight, serving as an early warning indicator.

Nitric oxide donor increases umbilical vein blood flow and fetal oxygenation in fetal growth restriction. A pilot study

INTRODUCTION

To evaluate the maternal and fetal hemodynamic effects of treatment with a nitric oxide donor and oral fluid in pregnancies complicated by fetal growth restriction.

METHODS

30 normotensive participants with early fetal growth restriction were enrolled. 15 participants were treated until delivery with transdermal glyceryl trinitrate and oral fluid intake (Treated group), and 15 comprised the untreated group. All women underwent non-invasive assessment of fetal and maternal hemodynamics and repeat evaluation 2 weeks later.

RESULTS

In the treated group, maternal hemodynamics improved significantly after two weeks of therapy compared to untreated participants. Fetal hemodynamics in the treated group showed an increase in umbilical vein diameter by 18.87 % (p < 0.01), in umbilical vein blood flow by 48.16 % (p < 0.01) and in umbilical vein blood flow corrected for estimated fetal weight by 30.03 % (p < 0.01). In the untreated group, the characteristics of the umbilical vein were unchanged compared to baseline. At the same time, the cerebro-placental ratio increased in the treated group, while it was reduced in the untreated group, compared to baseline values. The treated group showed a higher birthweight centile (p = 0.03) and a lower preeclampsia rate (p = 0.04) compared to the untreated group.

DISCUSSION

The combined therapeutic approach with nitric oxide donor and oral fluid intake in fetal growth restriction improves maternal hemodynamics, which becomes more hyperdynamic (volume-dominant). At the same time, in the fetal circuit, umbilical vein flow increased and fetal brain sparing improved. Although a modest sample size, there was less preeclampsia and a higher birthweight suggesting beneficial maternal and fetal characteristics of treatment.

Obstetric echodynamics: Approaching a new field of multidisciplinary action

Maternal cardiovascular adaptation during pregnancy is essential for fetal development. Structural and functional changes, including increased blood volume, heart rate, and myocardial hypertrophy, are crucial for optimal tissue perfusion. Recent evidence supports viewing maternal and fetal cardiovascular systems as a unified functional unit, emphasizing the significance of hemodynamic evaluation in pregnancy. Some obstetrical syndromes result from maladaptive maternal cardiovascular responses. Non-invasive hemodynamic tests, like transthoracic echocardiography, aid in distinguishing phenotypes, guiding tailored management strategies for hypertensive disorders. Establishing obstetric hemodynamics as a multidisciplinary field, termed "Obstetric Echodynamics," promises improved clinical care through standardized practices, interdisciplinary cooperation, and enhanced education.

Evaluation of the Caval aortic index in fetal growth restriction: A case-control study in a tertiary center

OBJECTIVE

To examine the inferior vena cava (IVC) diameter, aortic diameter, and caval aortic index in fetuses with growth restriction and to compare the findings with fetuses from uncomplicated pregnancies at similar gestational weeks.

METHODS

This prospective study was conducted with a total of 176 pregnant women. According to the diagnostic criteria, 84 pregnancies diagnosed with fetal growth restriction (FGR) were compared with a control group of 92 uncomplicated pregnancies at similar gestational weeks.

RESULTS

The aortic and IVC diameter values were significantly lower in the FGR group (P < 0.001), whereas the caval aortic index was similar between the two groups. The examination of the ultrasound parameters of the cases with FGR according to the neonatal intensive care requirement revealed similar aortic diameter and caval aortic index values but a significantly smaller IVC diameter in the cases requiring neonatal intensive care (P = 0.022).

CONCLUSION

We determined that the aortic and IVC diameter values were smaller in the fetuses with growth restriction, but the caval aortic index was similar in the two groups. The measurement of the IVC diameter in FGR may be useful in predicting the neonatal intensive care requirements of these fetuses.