Shorter sleep duration in early pregnancy is associated with birth length: a prospective cohort study in Wuhan, China
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Weiye Wang1, Chunrong Zhong2, Yu Zhang2
1Department of Epidemiology and Biostatistics, Ministry of Education Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Hubei, PR China.
Objectives:
To examine the association between sleep duration in early pregnancy and fetal growth in a prospective cohort study of 3567 Chinese women.
Methods:
Pregnant women at 8-16 weeks of gestation were interviewed using a semi-quantitative questionnaire to assess sleep duration. Birth weight and birth length were measured by a midwife in the delivery room at birth; low birth weight (LBW) was defined as birth weight <2500 g and small for gestational age (SGA) was defined as <10th customized centile.
Results:
The average age of participants was 28.21 ± 3.38 years old. The mean sleep duration was 8.39 ± 1.13 h/day. A total of 1290 women sleeping ≥9 h/day, 1563 sleeping 8 to <9 h/day, 550 sleeping 7 to <8 h/day, and 164 sleeping <7 h/day. Compared to the sleeping 8 to <9 h/day group, birth length and birth weight of the sleeping <7 h/day group decreased by 2.42 mm (95% CI: -4.27, -0.58, p = 0.010) and 42.70 g (95% CI: -103.02, 17.62, p = 0.165), respectively; and risk of LBW and SGA of the sleeping <7 h/day group increased by 83% (95% CI: 0.59, 5.73, p = 0.297) and 56% (95% CI: 0.84, 2.92, p = 0.159), respectively; birth length of the sleeping <7 h/day group was decreased more in male babies, and among mothers without a midday napping habit or with a history of abortion (all p for interaction <0.05).
Conclusions:
Shorter sleep duration in early pregnancy was associated with birth length. Our findings indicate that midday napping may be a protective factor for birth length among pregnant women with shorter sleep duration.
