Danielle L. Wilson

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

Objective The 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 Design We 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. Results Of 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. Conclusion OSA 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.

Decreased sleep efficiency, increased wake after sleep onset and increased cortical arousals in late pregnancy

Background:  Anecdotal reports of sleep disturbance during pregnancy are abundant; however, objective measurement of sleep changes has so far produced conflicting results.

Obstructive sleep apnea and pregnancy: the effect on perinatal outcomes.

Obstructive sleep apnea (OSA) is characterized by repeated episodes of upper airway obstruction, resulting in hypoxemia, hypercapnia and sleep fragmentation. Pathophysiological sequelae include sympathetic activation, increased oxidative stress and a generalized inflammatory response, culminating in endothelial dysfunction. These are the proposed mechanisms that mediate the increased risk of hypertension and cardiovascular disease among patients with OSA outside of pregnancy. It is intriguing to consider the consequences of these events on pregnancy outcomes. There is a growing literature on the impact of maternal OSA on hypertensive disorders of pregnancy, gestational diabetes and impaired fetal growth. The data, while promising, require confirmation with larger numbers to verify the findings. OSA may be an important mediator of the poor perinatal outcomes associated with maternal obesity; moreover, one which may be amenable to treatment. This review discusses OSA and summarizes the current literature linking OSA with adverse perinatal outcomes.

Subjective reports versus objective measurement of sleep latency and sleep duration in pregnancy.

This study compared self-reported sleep latency (SL) and total sleep time (TST) to objective measures on polysomnography (PSG) during pregnancy. Thirty-three women in the third trimester (T3) of pregnancy, 16 women in the first trimester (T1) of pregnancy, and 15 non-pregnant women underwent overnight PSG, and shortly after awakening reported their perceived SL and TST. Results showed that, on average, the T3 group slightly overestimated their TSTs, whereas the T1 and non-pregnant groups underestimated TSTs when compared with objective measurement. All groups overestimated SL, and perceived SL was closest to the first epoch of 10 min of uninterrupted sleep or the first epoch of slow-wave sleep, rather than the first epoch of sleep (the current definition used for diagnostic sleep studies). The wide variation in discrepancies between estimation and PSG measurement for both TST and SL shows that self-reports made by both pregnant and non-pregnant women tend to be unreliable, which has important implications both clinically and for the many studies based on self-reported sleep patterns in pregnancy.

Compromised verbal episodic memory with intact visual and procedural memory during pregnancy.

This study investigated episodic and procedural memory performance in early and late pregnancy. Twenty-six women in the third trimester of pregnancy, 20 women in the first trimester of pregnancy, and 24 nonpregnant controls were administered a battery of verbal and visual episodic memory tasks and two procedural memory tasks. Results indicated that compared to controls, both pregnant groups had reduced scores on immediate and delayed verbal episodic memory tasks, but were unimpaired on visual and procedural memory tasks. Verbal memory differences could not be accounted for by mood state or attention; however, progesterone level accounted for a small amount of the variation. Although memory differences were minor, the perception of memory problems may have implications for everyday living for pregnant women.

Treatment of early-onset preeclampsia with continuous positive airway pressure.

BACKGROUND: Preeclampsia is a leading cause of maternal and perinatal morbidity and mortality. There is no treatment for preeclampsia other than delivery. Sleep-disordered breathing is associated with adverse pregnancy outcomes, including preeclampsia, but it is not known whether treatment with continuous positive airway pressure (CPAP) improves perinatal outcomes. CASE: We report a 35-year-old primigravid woman diagnosed with preeclampsia at 30 weeks of gestation. A sleep study confirmed severe sleep-disordered breathing, and CPAP treatment was started. After CPAP treatment, both clinical and biochemical markers of preeclampsia improved. In addition, circulating angiogenic markers of preeclampsia improved. As a result, the pregnancy safely continued for 30 days, allowing the fetus to gain gestation. CONCLUSION: Continuous positive airway pressure may be a novel treatment for women with early-onset preeclampsia associated with sleep-disordered breathing.

Altering ventilator inspiratory time can reduce autocycling during sleep

• Autocycling is a form of patient–ventilator asynchrony (PVA) seen during non-invasive positive pressure ventilation (NIPPV).

Sleep‐disordered breathing in hypertensive disorders of pregnancy: a BMI‐matched study

Sleep‐disordered breathing is more common in hypertensive disorders during pregnancy; however, most studies have not adequately accounted for the potential confounding impact of obesity. This study evaluated the frequency of sleep‐disordered breathing in women with gestational hypertension and pre‐eclampsia compared with body mass index‐ and gestation‐matched normotensive pregnant women. Women diagnosed with gestational hypertension or pre‐eclampsia underwent polysomnography shortly after diagnosis. Normotensive controls body mass index‐matched within ±4 kg m−2 underwent polysomnography within ±4 weeks of gestational age of their matched case. The mean body mass index and gestational age at polysomnography were successfully matched for 40 women with gestational hypertension/pre‐eclampsia and 40 controls. The frequency of sleep‐disordered breathing in the cases was 52.5% compared with 37.5% in the control group (P = 0.18), and the respiratory disturbance index overall did not differ (P = 0.20). However, more severe sleep‐disordered breathing was more than twice as common in women with gestational hypertension or pre‐eclampsia (35% versus 15%, P = 0.039). While more than half of women with a hypertensive disorder of pregnancy meet the clinical criteria for sleep‐disordered breathing, it is also very common in normotensive women of similar body mass index. This underscores the importance of adjusting for obesity when exploring the relationship between sleep‐disordered breathing and hypertension in pregnancy. More severe degrees of sleep‐disordered breathing are significantly associated with gestational hypertension and pre‐eclampsia, and sleep‐disordered breathing may plausibly play a role in the pathophysiology of pregnancy hypertension in these women. This suggests that more severe sleep‐disordered breathing is a potential therapeutic target for reducing the prevalence or severity of hypertensive disorders in pregnancy.