Effects of Maternal Obstructive Sleep Apnoea on Fetal Growth: A Prospective Cohort Study

Abstract

ObjectiveThe objective of this study is to determine whether obstructive sleep apnea (OSA) is associated with reduced fetal growth, and whether nocturnal oxygen desaturation precipitates acute fetal heart rate changes.Study DesignWe performed a prospective observational study, screening 371 women in the second trimester for OSA symptoms. 41 subsequently underwent overnight sleep studies to diagnose OSA. Third trimester fetal growth was assessed using ultrasound. Fetal heart rate monitoring accompanied the sleep study. Cord blood was taken at delivery, to measure key regulators of fetal growth.ResultsOf 371 women screened, 108 (29%) were high risk for OSA. 26 high risk and 15 low risk women completed the longitudinal study; 14 had confirmed OSA (cases), and 27 were controls. The median (interquartile range) respiratory disturbance index (number of apnoeas, hypopnoeas or respiratory related arousals/hour of sleep) was 7.9 (6.1–13.8) for cases and 2.2 (1.3–3.5) for controls (p<0.001). Impaired fetal growth was observed in 43% (6/14) of cases, vs 11% (3/27) of controls (RR 2.67; 1.25–5.7; p = 0.04). Using logistic regression, only OSA (OR 6; 1.2–29.7, p = 0.03) and body mass index (OR 2.52; 1.09–5.80, p = 0.03) were significantly associated with impaired fetal growth. After adjusting for body mass index on multivariate analysis, the association between OSA and impaired fetal growth was not appreciably altered (OR 5.3; 0.93–30.34, p = 0.06), although just failed to achieve statistical significance. Prolonged fetal heart rate decelerations accompanied nocturnal oxygen desaturation in one fetus, subsequently found to be severely growth restricted. Fetal growth regulators showed changes in the expected direction- with IGF-1 lower, and IGFBP-1 and IGFBP-2 higher- in the cord blood of infants of cases vs controls, although were not significantly different.ConclusionOSA may be associated with reduced fetal growth in late pregnancy. Further evaluation is warranted to establish whether OSA may be an important contributor to adverse perinatal outcome, including stillbirth.

Maternal sleep-disordered breathing and the risk of delivering small for gestational age infants: a prospective cohort study

“…Of the two studies that used PSG-based diagnoses of SDB, one was a retrospective cohort study23 that showed no association and the other, a large database study22 demonstrated a positive association. One recent small study by Fung et al used PSG to study 51 pregnant women and identified 14 with sleep apnoea, which was associated with delivering babies with impaired fetal growth 41. These authors also used customised birthweight centiles to define SGA, but found a significant association between sleep apnoea and impaired fetal growth (defined as either a birth weight <10th centile or fall in customised centile >33% between 32 weeks and term) but not SGA defined by birth weight <10th centile alone 41.…”

Sleep-Disordered Breathing in Pregnancy

“…Fung et al [46] failed to find a difference in birth weight or SGA in their small cohort. However, when plotting fetal size at 32 weeks' gestation compared to birth centile, they did find that fetal growth trajectory fell across centiles in late pregnancy in women who had OSA.…”

“…Most studies that have longitudinally recruited women fail to find a relationship between maternal OSA and birth weight [46,47], SGA [46][47][48][49], or LGA [48]. Different polysomnographic systems were used across these studies and definitions of OSA varied by study.…”

Recognition of obstructive sleep apnea in pregnancy survey

“…Several studies and a meta-analysis suggest that OSA is associated with adverse perinatal outcomes, particularly when associated with hypertensive disorders of pregnancy which are major causes of maternal and fetal morbidity and mortality and result in significant healthcare expenditure. [1][2][3][4][5] Physicians and other healthcare providers who care for pregnant women should recognize symptoms and risk factors for OSA to enable effective screening. Research is needed to evaluate valid screening tools in the pregnant population.…”