Placental histology of acute versus continuous meconium exposure - Association with obstetric and neonatal outcomes.
OBJECTIVE
We aimed to compare obstetric and neonatal outcomes of deliveries complicated by meconium stained amniotic fluid (MSAF), according to placental histology of continuous vs. acute meconium associated changes.


METHODS
This was a retrospective cohort study of singleton deliveries complicated by MSAF at a single university-affiliated medical center during 2008-2018. Obstetric and neonatal outcomes were compared between cases with placental acute vs. continuous meconium exposure associated changes (columnar epithelial changes and meconium-laden macrophages, respectively). Regression analysis was used to identify independent associations with adverse neonatal outcomes.


RESULTS
The medical records of 294 deliveries at our institution were reviewed, along with medical records of the neonates and the histopathological reports of their placentas. Ninety-two cases were classified as an acute placental reaction to meconium (acute exposure group) and 200 as continuous placental exposure (continuous exposure group). Patient demographics did not differ between groups. Placentas from the continuous exposure to meconium were associated with a higher rate of placental weight <10th percentile (p = 0.03) while the acute exposure group was associated with a shorter time between rupture of membranes and delivery (p = 0.02). and higher rates of non-reassuring fetal heart rate in labor (p = 0.003), and of adverse neonatal outcome (p = 0.02). In multivariable analysis adverse neonatal outcome was associated with acute histologic exposure to meconium independent of background confounders (aOR = 1.51, 95% CI 1.12-3.67).


CONCLUSIONS
Acute histological changes of MSAF were independently associated with adverse neonatal outcomes as compared to continuous histologic MSAF.