Abstract
ObjectiveTo determine whether the presence of co-existing sleep-disordered breathing (SDB) is associated with worse perinatal outcomes among women diagnosed with a hypertensive disorder of pregnancy (HDP), compared with normotensive controls.Study designWomen diagnosed with HDP (gestational hypertension or preeclampsia) and BMI- and gestation-matched controls underwent polysomnography in late pregnancy to determine if they had coexisting SDB. Fetal heart rate (FHR) monitoring accompanied the sleep study, and third trimester fetal growth velocity was assessed using ultrasound. Cord blood was taken at delivery to measure key regulators of fetal growth.ResultsSDB was diagnosed in 52.5% of the HDP group (n = 40) and 38.1% of the control group (n = 42); p = .19. FHR decelerations were commonly observed during sleep, but the presence of SDB did not increase this risk in either the HDP or control group (HDP group—SDB = 35.3% vs. No SDB = 40.0%, p = 1.0; control group—SDB = 41.7% vs. No SDB = 25.0%, p = .44), nor did SDB affect the total number of decelerations overnight (HDP group—SDB = 2.7 ± 1.0 vs. No SDB = 2.8 ± 2.1, p = .94; control group—SDB = 2.0 ± 0.8 vs. No SDB = 2.0 ± 0.7, p = 1.0). Fetal growth restriction was the strongest predictor of fetal heart rate events during sleep (aOR 5.31 (95% CI 1.26–22.26), p = .02). The presence of SDB also did not adversely affect fetal growth; in fact among women with HDP, SDB was associated with significantly larger customised birthweight centiles (43.2% ± 38.3 vs. 16.2% ± 27.0, p = .015) and fewer growth restricted babies at birth (30% vs. 68.4%, p = .026) compared to HDP women without SDB. There was no impact of SDB on measures of fetal growth for the control group. Cord blood measures of fetal growth did not show any adverse effect among women with SDB, either in the HDP or control group.ConclusionWe did not find that the presence of mild SDB worsened fetal acute or longitudinal outcomes, either among women with HDP or BMI-matched normotensive controls. Unexpectedly, we found the presence of SDB conferred a better prognosis in HDP in terms of fetal growth. The fetus has considerable adaptive capacity to withstand in utero hypoxia, which may explain our mostly negative findings. In addition, SDB in this cohort was mostly mild. It may be that fetal sequelae will only be unmasked in the setting of more severe degrees of SDB and/or underlying placental disease.
Highlights
Sleep-disordered breathing (SDB) encompasses a spectrum of disorders characterised by increased upper airway resistance during sleep, and ranges from snoring to obstructive sleep apnoea (OSA)
Fetal heart rate (FHR) decelerations were commonly observed during sleep, but the presence of SDB did not increase this risk in either the Hypertensive disorders of pregnancy (HDP) or control group (HDP group—SDB = 35.3% vs. No SDB = 40.0%, p = 1.0; control group—SDB = 41.7% vs. No SDB = 25.0%, p = .44), nor did SDB affect the total number of decelerations overnight (HDP group—SDB = 2.7 ± 1.0 vs. No SDB = 2.8 ± 2.1, p = .94; control group—SDB = 2.0 ± 0.8 vs. No SDB = 2.0 ± 0.7, p = 1.0)
Fetal growth restriction was the strongest predictor of fetal heart rate events during sleep (aOR 5.31, p = .02)
Summary
Sleep-disordered breathing (SDB) encompasses a spectrum of disorders characterised by increased upper airway resistance during sleep, and ranges from snoring to obstructive sleep apnoea (OSA). The degree of OSA appears to be linearly related to cardiovascular risk.[8] Accumulating evidence suggests this relationship may exist in pregnancy with several studies reporting an association between SDB and gestational hypertensive disorders,[3,9,10] obesity can act as a confounder to this relationship. [11] Hypertensive disorders of pregnancy (HDP), preeclampsia, are associated with placental dysfunction resulting in impaired fetal growth and increased risks of acute compromise.[12,13,14,15] Whether co-existing SDB may increase these risks is currently unknown Accumulating evidence suggests this relationship may exist in pregnancy with several studies reporting an association between SDB and gestational hypertensive disorders,[3,9,10] obesity can act as a confounder to this relationship. [11] Hypertensive disorders of pregnancy (HDP), preeclampsia, are associated with placental dysfunction resulting in impaired fetal growth and increased risks of acute compromise.[12,13,14,15] Whether co-existing SDB may increase these risks is currently unknown
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