Evidence of Placental Hypoxia in Maternal Sleep Disordered Breathing

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.

Obstructive Sleep Apnea in Gestational Diabetes: A Pilot Study of the Role of the Hypothalamic-Pituitary-Adrenal Axis

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) in pregnancy is associated with gestational diabetes mellitus (GDM). This propensity toward heightened insulin resistance in OSA patients has not been well characterized and may be related to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis. The aim of this study was to (1) assess the prevalence of OSA in pregnant women with GDM, (2) evaluate whether HPA axis dysregulation relates to OSA, and (3) investigate the relation between insulin resistance and OSA. We hypothesized that OSA is prevalent among pregnant women with GDM and that women with OSA will have higher levels of insulin resistance and dysregulation of the HPA axis.

METHODS

Twenty-five pregnant women in whom GDM was diagnosed were enrolled. Subjects answered sleep questionnaires and underwent in-home sleep studies using a level III device. The presence of OSA was defined by apnea-hypopnea index ≥ 5 events/h. Homeostasis Model Assessment of insulin resistance was derived from measurements of fasting glucose and C-peptide levels. Three salivary cortisol levels were obtained across 1 day to assess circadian variation. Multivariable linear regression analyses were used to assess associations between variables.

RESULTS

The sample consisted of 54% Caucasian pregnant women with a median body mass index of 36.1 and interquartile ratio of 10.6 kg/m². OSA was diagnosed in 17% of participants. Circadian variation of cortisol was preserved in women with OSA. Women with OSA displayed blunted cortisol awakening responses.

CONCLUSIONS

OSA is prevalent in women with GDM. OSA is associated with preserved circadian variation and blunted cortisol awakening responses.

Maternal Sleep Quality and Diurnal Cortisol Regulation Over Pregnancy

Poor sleep in pregnancy is related to adverse neonatal health. Elevated maternal cortisol has been proposed as a pathway, yet the association in pregnancy is not well understood. The goals of the current study were to examine associations between (a) sleep and cortisol, (b) sleep, cortisol, and neonatal outcomes, and (c) variables that could explain these associations. Two hundred pregnant women completed the Pittsburgh Sleep Quality Index (PSQI; Buysse, Reynolds, Monk, Berman, & Kupfer, 1989) and provided diurnal salivary cortisol samples at two times over pregnancy. Poor sleep quality was associated with greater evening cortisol concentrations at 36 weeks' gestation. This association was mediated by anxiety symptoms. Higher evening cortisol at 36 weeks' gestation was associated with shorter gestation.

Obstructive sleep apnea in pregnancy is associated with adverse maternal outcomes: a national cohort

OBJECTIVE

Pregnancy and the obesity epidemic impacting women of reproductive age appear to predispose women to obstructive sleep apnea (OSA) in pregnancy. The aim of this study is to examine the association between OSA and adverse maternal outcomes in a national cohort.

METHODS

The National Perinatal Information Center in the US was used to identify women with a delivery discharge diagnosis of OSA from 2010 to 2014. We used the International Classification of Diseases, ninth Revision to classify OSA diagnosis and maternal outcomes.

MEASUREMENTS

The sample consisted of 1,577,632 gravidas with a rate of OSA of 0.12% (N = 1963). There was a significant association between OSA and preeclampsia (adjusted odds ratio (aOR) 2.22, 95% confidence interval (CI) 1.94-2.54), eclampsia (aOR 2.95, 1.08-8.02), and gestational diabetes (aOR 1.51, 1.34-1.72) after adjusting for a comprehensive list of covariates which includes maternal obesity. OSA status was also associated with a 2.5-3.5-fold increase in risk of severe complications such as cardiomyopathy, congestive heart failure, and hysterectomy. Length of hospital stay was significantly longer (5.1 + 5.6 vs 3.0 + 3.0 days, p < 0.001) and odds of an admission to an intensive care unit higher (aOR 2.74, 2.36-3.18) in women with OSA.

CONCLUSIONS

Compared to pregnant women without OSA, pregnant women with OSA have a significantly higher risk of pregnancy-specific complications such as gestational hypertensive conditions and gestational diabetes, and rare medical and surgical complications such as cardiomyopathy, pulmonary edema, congestive heart failure, and hysterectomy. OSA diagnosis was also associated with a longer hospital stay and significantly increased odds for admission to the intensive care unit.

Late gestational intermittent hypoxia induces metabolic and epigenetic changes in male adult offspring mice

KEY POINTS

Late gestation during pregnancy has been associated with a relatively high prevalence of obstructive sleep apnoea (OSA). Intermittent hypoxia, a hallmark of OSA, could impose significant long-term effects on somatic growth, energy homeostasis and metabolic function in offspring. Here we show that late gestation intermittent hypoxia induces metabolic dysfunction as reflected by increased body weight and adiposity index in adult male offspring that is paralleled by epigenomic alterations and inflammation in visceral white adipose tissue. Fetal perturbations by OSA during pregnancy impose long-term detrimental effects manifesting as metabolic dysfunction in adult male offspring.

ABSTRACT

Pregnancy, particularly late gestation (LG), has been associated with a relatively high prevalence of obstructive sleep apnoea (OSA). Intermittent hypoxia (IH), a hallmark of OSA, could impose significant long-term effects on somatic growth, energy homeostasis, and metabolic function in offspring. We hypothesized that IH during late pregnancy (LG-IH) may increase the propensity for metabolic dysregulation and obesity in adult offspring via epigenetic modifications. Time-pregnant female C57BL/6 mice were exposed to LG-IH or room air (LG-RA) during days 13-18 of gestation. At 24 weeks, blood samples were collected from offspring mice for lipid profiles and insulin resistance, indirect calorimetry was performed and visceral white adipose tissues (VWAT) were assessed for inflammatory cells as well as for differentially methylated gene regions (DMRs) using a methylated DNA immunoprecipitation on chip (MeDIP-chip). Body weight, food intake, adiposity index, fasting insulin, triglycerides and cholesterol levels were all significantly higher in LG-IH male but not female offspring. LG-IH also altered metabolic expenditure and locomotor activities in male offspring, and increased number of pro-inflammatory macrophages emerged in VWAT along with 1520 DMRs (P < 0.0001), associated with 693 genes. Pathway analyses showed that genes affected by LG-IH were mainly associated with molecular processes related to metabolic regulation and inflammation. LG-IH induces metabolic dysfunction as reflected by increased body weight and adiposity index in adult male offspring that is paralleled by epigenomic alterations and inflammation in VWAT. Thus, perturbations to fetal environment by OSA during pregnancy can have long-term detrimental effects on the fetus, and lead to persistent metabolic dysfunction in adulthood.

Serum Progesterone Levels in Pregnant Women with Obstructive Sleep Apnea: A Case Control Study

BACKGROUND

Pregnancy is a risk factor for sleep disordered breathing, including obstructive sleep apnea (OSA). Progesterone, one of the key hormones in pregnancy, a known respiratory drive stimulant, increases ventilation and may protect against OSA. We aimed to examine the relationship between circulating progesterone and OSA, after accounting for body weight and gestational age.

METHODS

A case control study was conducted of pregnant women with OSA and those at low risk for the disorder. Cases were identified by ICD-9 code and review of medical record. Controls were identified if they scored zero (never) for snoring, apnea, and gasping on the multivariable apnea prediction index questionnaire immediately following delivery. Subjects with available stored first and/or second trimester residual serum samples were then included in this study and serum analyzed for progesterone. Raw progesterone levels were adjusted for the effects of gestational age and maternal weight.

RESULTS

Twenty-seven cases and 64 controls with available serum were identified. Women with OSA had greater maternal weight and higher rates of related comorbidities, compared to controls. Progesterone levels correlated positively with gestational age and negatively with greater weight. Progesterone levels, adjusted for gestational age and maternal weight and expressed as multiples of median (MoM), were significantly lower in OSA cases compared to controls in both the first trimester (MoM = 0.71, confidence interval [95% CI] 0.60-0.83) relative to the MoM in controls of 1.00. In the second trimester levels were also lower in OSA cases (MoM = 0.84, 95% CI 0.73-0.96) compared to the MoM of 1.00 in controls.

CONCLUSIONS

Progesterone levels, after accounting for weight and gestational age, were lower in women with OSA than controls. Progesterone may play a protective role against OSA.

Effects of Gestational and Postnatal Exposure to Chronic Intermittent Hypoxia on Diaphragm Muscle Contractile Function in the Rat

Alterations to the supply of oxygen during early life presents a profound stressor to physiological systems with aberrant remodeling that is often long-lasting. Chronic intermittent hypoxia (CIH) is a feature of apnea of prematurity, chronic lung disease, and sleep apnea. CIH affects respiratory control but there is a dearth of information concerning the effects of CIH on respiratory muscles, including the diaphragm-the major pump muscle of breathing. We investigated the effects of exposure to gestational CIH (gCIH) and postnatal CIH (pCIH) on diaphragm muscle function in male and female rats. CIH consisted of exposure in environmental chambers to 90 s of hypoxia reaching 5% O2 at nadir, once every 5 min, 8 h a day. Exposure to gCIH started within 24 h of identification of a copulation plug and continued until day 20 of gestation; animals were studied on postnatal day 22 or 42. For pCIH, pups were born in normoxia and within 24 h of delivery were exposed with dams to CIH for 3 weeks; animals were studied on postnatal day 22 or 42. Sham groups were exposed to normoxia in parallel. Following gas exposures, diaphragm muscle contractile, and endurance properties were examined ex vivo. Neither gCIH nor pCIH exposure had effects on diaphragm muscle force-generating capacity or endurance in either sex. Similarly, early life exposure to CIH did not affect muscle tolerance of severe hypoxic stress determined ex vivo. The findings contrast with our recent observation of upper airway dilator muscle weakness following exposure to pCIH. Thus, the present study suggests a relative resilience to hypoxic stress in diaphragm muscle. Co-ordinated activity of thoracic pump and upper airway dilator muscles is required for optimal control of upper airway caliber. A mismatch in the force-generating capacity of the complementary muscle groups could have adverse consequences for the control of airway patency and respiratory homeostasis.