Study objectives: This study was designed to evaluate sleep-related disordered breathing in obese women during pregnancy. Obesity is known to predispose to sleep-related breathing disorders. During pregnancy, obese mothers gain additional weight, but other mechanisms may counteract this effect.
Design: A case-control study to compare sleep-related breathing in obese pregnant women (mean prepregnancy body mass index [BMI] > 30 kg/m(2)) with pregnant women of normal weight (mean BMI, 20 to 25 kg/m(2)).
Setting: University teaching hospital with a sleep laboratory.
Participants: We recruited 11 obese women (BMI, 34 kg/m(2); mean age 31 years) and 11 control women (BMI, 23 kg/m(2); mean age 32 years).
Interventions: Overnight polysomnography was performed during early (after 12 weeks) and late (after 30 weeks) pregnancy.
Measurements and results: During pregnancy, obese mothers gained 13 kg and control women gained 16 kg. Sleep characteristics did not differ between the groups. During late pregnancy, the women in both groups slept more poorly and slept in supine position less. During early pregnancy, their apnea-hypopnea indexes (1.7 events per hour vs 0.2 events per hour; p < 0.05), 4% oxygen desaturations (5.3 events per hour vs 0.3 events per hour; p < 0.005), and snoring times (32% vs 1%, p < 0.001) differed significantly. These differences between the groups persisted in the second polysomnography, with snoring time further increasing in the obese. Preeclampsia and mild obstructive sleep apnea were diagnosed in one obese mother. One obese mother delivered a baby showing growth retardation (weight - 3 SD).
Conclusions: We have shown significantly more sleep-related disordered breathing occurring in obese mothers than in subjects of normal weight, despite similar sleeping characteristics.