A study published in American Journal of Respiratory and Critical Care Medicine found that sleep disordered breathing in pregnancy led to a higher risk of both metabolic disease and hypertension up to 7 years post partum.
Sleep disordered breathing (SDB), especially obstructive sleep apnea (OSA), is becoming more common in pregnancy, which itself increases the risk of SDB because of physical and hormonal changes. A recent study published online in American Journal of Respiratory and Critical Care Medicine found that SDB during pregnancy led to a 3-fold risk of hypertension and a 2-fold risk of metabolic syndrome compared with no SDB during pregnancy.
People with SDB, including OSA, experience apneas and hypopneas throughout sleep, causing intermittent hypoxemia and disrupted sleep. The overall prevalence of SDB in pregnant populations in 33 studies was 15%, according to a meta-analysis noted by the study authors. During pregnancy, SDB also has been associated with a higher risk of preeclampsia and gestational diabetes.
In middle-aged or older adults, SDB is associated with poor cardiometabolic outcomes such as metabolic syndrome and hypertension, but the effects of SDB on maternal health after pregnancy have not been confirmed. This study aimed to find out if SDB during pregnancy leads to adverse health events after delivery for younger women.
A subgroup of first-time moms who took part in the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-be Heart Health Study (nuMoM2b-HHS) who also had adequate sleep data from the study period available were eligible for the new study. Those who had an Apnea Hypopnea Index (AHI) score or oxygen desaturation index (ODI) score of 5 or higher—meaning 5 or more instances of breathing cessation or drops in oxygen saturation per hour during sleep—were considered to have SDB.
Of 1964 nuMoM2b-HHS participants who also took part in a sleep study during their first pregnancy, 1222 took part in a repeat sleep study at a follow-up between 2 and 7 years later. Adequate sleep data were available for 1069 participants. Twelve percent in this subgroup had SDB defined by AHI (SDB-AHI) at a median 32 months after delivery.
There were 844 participants with SDB data across early-pregnancy, midpregnancy, and follow-up visits. Of those participants, 5.8% showed SDB during pregnancy that persisted after delivery, 2.6% had SDB during pregnancy that was resolved by follow-up, and 7.5% had new-onset SDB by the time of follow-up.
Participants with SDB-AHI in pregnancy had worse metabolic and cardiovascular outcomes. They had a higher body. Mass index, larger waist circumference, higher systolic and diastolic blood pressures, higher triglyceride levels and fasting blood glucose, and lower high-density lipoprotein cholesterol (HDL-C) levels at postdelivery follow-ups.
During pregnancy, incident hypertension and metabolic syndrome were more common in those who had SDB vs those who did not (15.7% vs 6.2% and 40.2% vs 14.2%). However, adjusted risk ratios showed that SDB during pregnancy was not associated with a higher risk of incident hypertension. The adjusted risk ratio (aRR) for metabolic syndrome, given SDB-AHI during pregnancy, was 1.44 (95% CI, 1.08-1.93).
At follow-up, SDB as determined by ODI (SDB-ODI) during pregnancy was associated with a higher risk of metabolic syndrome (aRR, 1.53; 95% CI, 1.19-1.97). Those with an ODI of 15 or higher mid pregnancy had a greater risk of metabolic syndrome (aRR, 2.57; 95% CI, 0.82-8.01).
Adjusted analyses showed that SDB-AHI in pregnancy was associated with elevated triglycerides and reduced HDL-C, while SDB-ODI during pregnancy was associated with elevated triglycerides and blood pressure. Participants with persistent SDB, defined using either AHI or ODI, had the highest risk for incident hypertension and metabolic syndrome with aRRs from 2.3 to 3.8.
“Associations of SDB in pregnancy were generally stronger when SDB was defined using the ODI, which quantified the frequency of drops in oxygen saturation of at least 3%, than the AHI, which was defined by a combination of changes in airflow and oxygen saturation,” the authors wrote. “Participants with persistent elevations in AHI or ODI during pregnancy and 2- to 7-year follow-up visits were at more than 3-fold increased risk for incident hypertension and more than a 2-fold increased risk for metabolic syndrome.”
Further studies are needed to identify temporal or causal relationships between SDB and cardiometabolic risks and to determine whether simple oximetry monitoring vs AHI measurement can be used to identify at-risk patients. More research could also determine if treatment with the standard of care, continuous positive air pressure, for SDB during pregnancy would modify the cardiometabolic risks associated with it.
Facco FL, Redline S, Hunter SM, et al. Sleep disordered breathing in pregnancy and post-delivery: associations with cardiometabolic health. Am J Respir Crit Care Med. Published online February 11, 2022. doi:10.1164/rccm.202104-0971OC