Experimental and epidemiologic data suggest that among non-pregnant adults, sleep duration may be an important risk factor for chronic disease. Although pregnant women commonly complain of poor sleep, few studies have objectively evaluated the quality of sleep in pregnancy or have explored the relationship between sleep disturbances and maternal and perinatal outcomes.
Our objective was to examine the relationship between objectively assessed sleep duration, timing and continuity (measured via wrist actigraphy) and maternal cardiovascular and metabolic morbidity specific to pregnancy.
This was a prospective cohort study of nulliparous women. Women were recruited between 16 0/7 and 21 6/7 weeks' gestation. They were asked to wear a wrist actigraphy monitor and to complete a daily sleep log for a seven consecutive-day period. The primary sleep exposure variables were the averages of the following over the total valid nights (minimum 5, maximum 7 nights): short sleep duration during the primary sleep period (< 7 hours/night), late sleep midpoint (midpoint between sleep onset and sleep offset > 5 AM), and top quartile of minutes of wake time after sleep onset (WASO) and sleep fragmentation index. The primary outcomes of interest were a composite of hypertensive disorders of pregnancy (mild, severe, or superimposed preeclampsia; eclampsia; or antepartum gestational hypertension) and gestational diabetes (GDM). Chi-square tests were used to assess associations between sleep variables and categorical baseline characteristics. Crude odds ratios and 95% confidence intervals were estimated from univariate logistic regression models to characterize the magnitude of the relationship between sleep characteristics and hypertensive disorders of pregnancy and GDM. For associations that were significant in univariate analysis, multiple logistic regression was used to explore further the association of sleep characteristics with pregnancy outcomes.
Nine-hundred and one eligible women consented to participate. Of these women 782 submitted valid actigraphy studies. Short sleep duration and a later sleep midpoint were associated with an increased risk of GDM (OR 2.24, 95% CI 1.11, 4.53; OR 2.58, 95% CI 1.24, 5.36, respectively) but not of hypertensive disorders. A model with both sleep duration and sleep midpoint as well as their interaction term revealed that while there was no significant interaction between these exposures, the main effects of both short sleep duration and later sleep midpoint with GDM remained significant (aOR 2.06, 95% CI 1.01, 4.19; aOR 2.37, 95% CI 1.13, 4.97, respectively). Additionally, after adjusting separately for age, BMI and race/ethnicity, both short sleep duration and later sleep midpoint remained associated with GDM. No associations were demonstrated between the sleep quality measures (WASO, sleep fragmentation) and hypertensive disorders or GDM.
Our results demonstrate a relationship between short sleep duration and later sleep midpoint with GDM. Our data suggest independent contributions of these two sleep characteristics to the risk for GDM in nulliparous women.