Effect of nighttime sleep duration and midday napping in early pregnancy on gestational diabetes mellitus.

Purpose: To explore the effect of nighttime sleep duration and midday napping in early pregnancy on gestational diabetes mellitus (GDM) among Chinese women.

Methods: Information on midday napping and nighttime sleep duration was assessed by a questionnaire. Diagnostic information of GDM was derived from the routine oral glucose tolerance test (OGTT) during the second trimester of pregnancy.

Results: A total of 500 pregnant women, including 196 patients with GDM and 304 controls, were included in the present study. In the case group, 47% of women took a midday nap > 1 h/day, and the proportion was 22% in the control group. Compared with women who had a midday nap ≤ 1 h/day, women who had a nap > 1 h/day had a significantly increased risk of GDM (OR 3.00, 95% CI 1.87, 4.82, p < 0.001). Compared with women who had a nighttime sleep of 7 to 8.9 h/night, women who slept < 7 or ≥ 9 h/night all had a significantly increased risk of GDM. Stratified analyses showed that compared with the nighttime sleep duration of 7 to 8.9 h/day, the GDM risk of the < 7 h/night group increased among mothers who had a midday nap ≤ 1 h/day. The impact was stronger than among women who had a nap > 1 h/day (p = 0.006).

Conclusions: Shorter or longer nighttime sleep duration and longer midday napping duration in early pregnancy were all related to GDM. Midday napping would reduce the risk of GDM among mothers with shorter nighttime sleep duration.