Contemporary practice patterns in the use of amniocentesis for fetal lung maturity

Fetal maturation revealed by amniotic fluid cell-free transcriptome in rhesus macaques

Accurate estimate of fetal maturity could provide individualized guidance for delivery of complicated pregnancies. However, current methods are invasive, have low accuracy, and are limited to fetal lung maturation. To identify diagnostic gestational biomarkers, we performed transcriptomic profiling of lung and brain, as well as cell-free RNA from amniotic fluid of preterm and term rhesus macaque fetuses. These data identify potentially new and prior-associated gestational age differences in distinct lung and neuronal cell populations when compared with existing single-cell and bulk RNA-Seq data. Comparative analyses found hundreds of genes coincidently induced in lung and amniotic fluid, along with dozens in brain and amniotic fluid. These data enable creation of computational models that accurately predict lung compliance from amniotic fluid and lung transcriptome of preterm fetuses treated with antenatal corticosteroids. Importantly, antenatal steroids induced off-target gene expression changes in the brain, impinging upon synaptic transmission and neuronal and glial maturation, as this could have long-term consequences on brain development. Cell-free RNA in amniotic fluid may provide a substrate of global fetal maturation markers for personalized management of at-risk pregnancies.

Fetal lung development via quantitative biomarkers from diffusion MRI and histological validation in rhesus macaques

OBJECTIVE

To demonstrate sensitivity of diffusion-weighted MRI (DW-MRI) to pulmonary cellular-space changes during normal in utero development using fetal rhesus macaques, compared to histological biomarkers.

STUDY DESIGN

In vivo/ex vivo DW-MRI was acquired in 26 fetal rhesus lungs (early-canalicular through saccular stages). Apparent diffusion coefficients (ADC) from MRI and tissue area density (H&E), alveolar type-II cells (ABCA3), and epithelial cells (TTF1) from histology were compared between gestational stages.

RESULTS

In vivo/ex vivo ADC correlated with each other (Spearman ρ = 0.47, P = 0.038; Bland-Altman bias = 0.0835) and with area-density (in vivo ρ = -0.56, P = 0.011; ex vivo ρ = -0.83, P < 0.0001). In vivo/ex vivo ADC increased exponentially toward saturation with gestational stage (R² = 0.49/0.49), while area-density decreased exponentially (R² = 0.53). ABCA3 and TTF1 stains demonstrated expected fetal cellular development.

CONCLUSIONS

Fetal DW-MRI provides a non-invasive biomarker for pulmonary structural maturation, with a strong correlation to histological markers during tissue development in rhesus macaques. This method has strong potential for assessing human fetal development, particularly in patients with pulmonary hypoplasia.

Amniocentesis compared with antenatal corticosteroids prior to early term scheduled cesarean delivery

Objective: There are a variety of maternal or fetal conditions that require late preterm or early term delivery. In cases where early delivery is indicated, optimal management is not always clear. Historically, obstetricians used amniocentesis to document fetal lung maturity, but recently, many have transitioned to administration of antenatal corticosteroids (ACS). The objective of this study was to compare neonatal outcomes between women undergoing amniocentesis or receiving ACS prior to scheduled cesarean delivery (CD) less than 39 weeks. Methods: This was a retrospective cohort study of women undergoing scheduled CD by one maternal-fetal medicine practice between 36 and 38 6/7 weeks, from 2005 to 2017. We identified women who underwent amniocentesis or received ACS within 2 weeks prior to delivery. Neonatal outcomes were compared between the two groups, with the primary outcome being neonatal intensive care unit (NICU) admission. Results: A total of 502 women were included, of whom 313 (62.4%) underwent amniocentesis and 189 (37.6%) received ACS. Overall, 55 (11.0%) of neonates were admitted to the NICU. NICU admission was not significantly different between groups (11.8 versus 9.5%, p=.46). This held true after adjusting for gestational age and other differences in baseline characteristics. There were no significant differences between groups for all other neonatal outcomes, including NICU admission for respiratory indications, respiratory support, neonatal greater than maternal length of stay, low Apgar scores, and neonatal death. Rates of hypoglycemia were low and not significantly different between groups (2.2% in the amniocentesis group versus 0.5% in the ACS group, p=.27). Diabetes was the only covariate significantly associated with NICU admission (aOR 3.19, 95% CI 1.35, 7.54). Conclusions: In women undergoing scheduled CD between 36 and 38 6/7 weeks, administration of ACS is associated with similar neonatal outcomes compared to amniocentesis. This supports the current notion that outcomes are similar with ACS compared to amniocentesis for late preterm and early term deliveries. Brief rationale: The objective of this study was to compare neonatal outcomes between women undergoing amniocentesis or receiving antenatal corticosteroids (ACS) prior to scheduled cesarean delivery (CD) less than 39 weeks. We found that in women undergoing scheduled cesarean delivery between 36 and 38 6/7 weeks, administration of antenatal corticosteroids is associated with similar neonatal outcomes compared to amniocentesis.