Changes in fetoplacental Doppler indices following intrapartum maternal sildenafil citrate treatment

OBJECTIVE

Uterine contractions during labour can result in a 60 % decline in fetoplacental perfusion, predisposing the fetus to hypoxic brain injury. Sildenafil citrate (SC) has shown promise in increasing uteroplacental perfusion as well as reducing the risk of operative birth for intrapartum fetal compromise (IFC). The aim of this study was to investigate the effect of intrapartum SC administration on fetoplacental blood flow indices.

METHODS

This was a subgroup analysis from an earlier Phase II double blind randomized controlled trial; assessing the effect of intrapartum SC administration (50 mg orally 8 -hly in labour) compared to placebo for the reduction of operative birth for IFC. An ultrasound scan measuring fetoplacental Doppler indices was performed prior to and 1-4 h after the administration of the first treatment dose.

RESULTS

Of the 300 women randomized to the main study, pre-treatment ultrasound scans were performed in 261 participants who received the study medication; paired pre- and post-treatment scans were performed in 70 (26.8 %). SC resulted in an increase in the middle cerebral artery pulsatility index (PI) z-score [+0.08 (1.35) vs.-0.12 (1.15)], a decline in the umbilical artery-PI z-score [-0.07 (0.96) vs. + 0.04 (1.25)] and an increase in the cerebroplacental ratio [MCA-PI/UA-PI] (CPR) z-score [+0.10 (1.13) vs.-0.26 (1.14)] although these failed to reach statistical significance. Amongst those with a pre-treatment CPR above the 5th centile, SC significantly reduced the risk of operative birth for IFC compared to placebo [logrank p = 0.02; hazards ratio 0.48, 95 % CI 0.29-0.77, p = 0.003].

CONCLUSION

Although the differences in Doppler indices pre- and post- SC treatment were non-significant, there was a clear trend towards a reduction in the UA PI, a corresponding increase in the MCA PI and a rise in post treatment CPR values suggesting potential improvement in fetoplacental Dopplers with intrapartum SC treatment. However this study was limited by the small sample size. The results of this hypothesis generating study suggest that it may be possible to stratify women that would most benefit from this intervention based upon their pre-labour CPR.

Reduced growth velocity at term is associated with adverse neonatal outcomes in non-small for gestational age infants

OBJECTIVES

To investigate the association between decreased growth velocity at term, measured by estimated fetal weight z-score change, and adverse neonatal outcome and operative birth for intrapartum fetal compromise in a cohort of non-small for gestational age infants.

STUDY DESIGN

A prospective observational study was conducted at Mater Mothers' Hospital, Brisbane, Australia. Serial ultrasound assessment was undertaken every two weeks from 36 weeks gestation until delivery to determine estimated fetal weight on 436 women with uncomplicated pregnancies. Intrapartum and neonatal outcomes were recorded. The outcome measures were adverse neonatal outcome [severe acidosis (cord pH < 7.0, base deficit ≤-12 mmol/L and/or lactate >6 mmol/L), low Apgar score (<7 at 5 min) or neonatal intensive care unit admission] and operative delivery for intrapartum fetal compromise. Estimated fetal weight z-score change was compared between those with and without adverse neonatal outcome and operative delivery for intrapartum fetal compromise using Generalised Linear Mixed Models.

RESULTS

The estimated fetal weight z-score per week declined for infants with the adverse neonatal outcome whilst those without demonstrated an increase [-0.04 (0.18) vs. 0.02 (0.21), p = 0.02]. There was no difference in estimated fetal weight z-score change per week in those with and without operative delivery for intrapartum fetal compromise.

CONCLUSION

Reduced growth velocity in non-small for gestational age fetuses at term is associated with an increased risk of adverse neonatal outcomes.

A low fetal cerebroplacental ratio confers a greater risk of intrapartum fetal compromise and adverse neonatal outcomes in low risk multiparous women at term

BACKGROUND

A low fetal cerebroplacental ratio (CPR) and nulliparity have independently been shown to be associated with adverse obstetric and perinatal outcomes.

OBJECTIVES

To assess the effect of parity on the CPR and investigate the utility of a CPR threshold of <10^th centile for predicting adverse outcomes. We hypothesised that nulliparous women would have a lower CPR than multiparous women, impacting the diagnostic performance of the <10^th centile threshold. This is an important consideration for interpretation of a low CPR in clinical practice.

STUDY DESIGN

This was a retrospective cohort study of low risk, singleton pregnancies delivering at term in Australia's largest maternity hospital. The primary outcome was emergency caesarean section for intrapartum fetal compromise (EmCS IFC). Data was dichotomised according to parity and further by CPR <10^th centile. Multiple logistic regression was performed.

RESULTS

4737 women were included for analysis, 2333 were nulliparous and 2404 were multiparous. Overall the z-score (mean [SD])(CPR standardised for gestation) was lower in nulliparous compared to multiparous women (-0.16 [-1.73 - 1.42] vs 0.04 [-1.63 - 1.69], p < 0.001). Multiparous women had a non-significantly lower mean z-score for those who delivered by EmCS IFC than nulliparous women (-0.52 [-2.23 - 2.02] vs -0.45 [-2.22 - 1.1]). Nulliparous women had greater odds of having a CPR <10^th centile compared to the multiparous cohort (OR 1.24, 95% CI 1.02-1.5 vs. OR 0.81, 95% CI 0.7-0.98, p < 0.001). A CPR thresholdd <10^th centile in nulliparous women was associated with increased odds of intrapartum fetal compromise (IFC), EmCS IFC (aOR 1.72, 95CI 1.2-2.6, p < 0.05) and birthweight <10^th centile. A low CPR in multiparous women was associated with increased odds of all adverse perinatal outcomes measured: IFC, meconium stained liquor, EmCS IFC (aOR 4.99, 95%CI 2.5-9.9, p < 0.001), birthweight <10^th centile, acidosis, neonatal intensive care admission and severe composite neonatal outcome. These aORs were associated with specificities of >90% and false positive rates of <10% for all outcomes in multiparous women.

CONCLUSIONS

A CPR <10^th centile in multiparous women confers greater odds of adverse perinatal outcomes and as such of the influence of parity should be taken into account when decisions regarding clinical management are made because of a low CPR.

Screening Performance of Placental Growth Factor for the Prediction of Low Birth Weight and Adverse Intrapartum and Neonatal Outcomes in a Term Low-Risk Population

INTRODUCTION

Fetuses who fail to reach their genetic growth potential are thought to have sub-optimal placental function. Low placental growth factor (PlGF) levels have been shown to be predictive of placentally mediated conditions, such as pre-eclampsia or fetal growth restriction. We investigated the screening performance of PlGF for the prediction of low birth weight (<10th centile for gestation) and adverse intrapartum and neonatal outcomes in apparently low-risk term pregnancies.

MATERIALS AND METHODS

Maternal PlGF levels were measured fortnightly in a blinded, prospective, observational study from 36 weeks of pregnancy. Women and clinicians were blinded to PlGF results, and pregnancies were managed according to local policies and guidelines. Intrapartum and neonatal outcomes were recorded. PlGF was analysed for association with, and predictive capacity for, low birth weight, caesarean section for intrapartum fetal compromise (CS-IFC) and adverse neonatal outcomes.

RESULTS

A total of 438 women were included in the final analysis. Lower PlGF levels were associated with low birth weight, CS-IFC and adverse neonatal outcome. For a false-positive rate of 10 and 20%, respectively, the corresponding sensitivities were 9.7-11.1% and 22.2-26.8%.

CONCLUSION

As a sole predictor for low birth weight, CS-IFC and adverse neonatal outcome, PlGF was poor as a test.