The effect of maternal obstructive sleep apnea on the placenta

Study Objectives: Obstructive sleep apnea (OSA) during pregnancy has been associated with adverse maternal outcomes. However, the effect of maternal OSA on fetal growth is less clear. The placenta is a critical organ for fetal growth and development and the principal determinant of birthweight. We aimed to investigate the effect of maternal OSA on placental growth and function. Methods: Placentas of women recruited to a prospective longitudinal study were consecutively obtained immediately after delivery. Each placenta was measured for length, width, and thickness. Total RNA was isolated for gene expression analysis of VEGF, VEGF receptor, PIGF, and leptin. Histological and morphometric evaluations of the placenta were performed. Results: A total of 53 placentas were investigated. Ten women (19%) had OSA, and the weight of their placentas was significantly higher compared with the placentas of the controls (526.1 ± 83.9 vs. 425.7 ± 95.5 g, p = 0.004). There was a significant positive correlation between placental weight and the log apnea-hypopnea index even after controlling for maternal body mass index (BMI; r = 0.31, p = 0.04). The birthweight/placental weight ratio was significantly lower in women with OSA compared with controls (p = 0.03). Placental weight and newborn triceps adiposity thickness correlated positively after controlling for maternal BMI (r = 0.29, p = 0.04). Leptin expression was 1.8-fold higher in placentas of women with OSA compared with controls (p = 0.02). No histological differences were found between the groups. Conclusions: Maternal OSA is associated with increased placental weight that correlated with OSA severity and neonatal adiposity independently of maternal BMI. Placental leptin overexpression may mediate/underlie the above findings.