Effects of pregnancy on mothers' sleep

Abstract

Objectives: To survey the effects of pregnancy on mothers' sleep.

Methods: Mothers were interviewed during and after pregnancy with a series of five questionnaires to assess alterations in their sleep. The first questionnaire covered the 3 months before becoming pregnant, the next three the trimesters of pregnancy and the last the 3 months after delivery. The study was carried out in a central hospital and the maternity care units in the nearby rural community. Altogether, 325 pregnant women completed all five questionnaires.

Results: The total amounts of reported sleep and of nocturnal sleep increased significantly during the first trimester of pregnancy, began to decrease thereafter and were shortest during the 3 months after pregnancy. During late pregnancy expectant mothers over 30 years of age reported less sleep than those under 30. During the whole pregnancy, but increasingly toward the end of pregnancy, sleep became more restless and fragmentary and its subjective quality worsened, due at least partly to increased restless legs and nightly awakenings increasing with advancing pregnancy.

Conclusions: The subjective quality of sleep is disturbed as early as the first trimester of pregnancy, although total sleeping time increases. The amount of reported sleep begins to decrease in the second trimester. The frequency of reported sleep disturbances, such as restless legs syndrome and nocturnal awakenings, is maximum in the third trimester but is about normal within 3 months after delivery.

Introduction

Pregnancy alters sleep in many ways [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], but only a few studies with a large sample size have assessed the quantity and quality of the sleep of mothers before, during and after pregnancy.

According to earlier studies, an increase in total sleep time and daytime sleepiness is noted during the first trimester, whereas the third trimester and especially the first postpartum month [8] are characterized by a decrease in sleep time and an increase in the number of nocturnal awakenings [2], [5], [10]. In a recent study, at the 6 week prenatal care unit visit 37.5% of the young, healthy pregnant women questioned reported daytime sleepiness of variable severity, but later at the 6 month visit this was noted in 52% of the subjects [11]. The frequency of restless legs syndrome has been reported to increase during pregnancy, occurring in one-third of mothers [12], [13], [14].

In a self-reporting survey, Loube et al. [15] found snoring to be significantly more frequent in 350 pregnant women than in 110 age-matched non-pregnant women. Loud snoring reported by bed partners occurred in 3.7% of the pre-pregnant study population and increased to 11.8% by the 6 month prenatal visit [11]. In a recent cross-sectional consecutive case series of 502 women with singleton pregnancies, Franklin et al. [9] reported that 23% of the women questioned snored every night during the last week of pregnancy (but only 4% before becoming pregnant) and found snoring during pregnancy to be associated with hypertension, pre-eclampsia and even growth retardation of the fetus. Brownell et al. [6] reported that the frequency of apneas and hypopneas of six pregnant women was significantly reduced during pregnancy, but the opposite has also been observed [7]. It has recently been shown [16] that nasal continuous positive airway pressure reduces sleep-induced blood pressure increments in pre-eclampsia.

Hormonal changes during pregnancy have many effects on sleep [1], [6], [17] and may cause fatigue and energy loss [18]. Estrogen is known to cause nasal edema, while the high level of circulating progesterone facilitates breathing during sleep. Though it has been found that oxygenation is well maintained [6], in some studies oxygen saturation declines in pregnant women [1]. Guilleminault et al. [11] reported that in young, healthy pregnant women who snored during pregnancy, minor oxygenation drops during sleep were associated with the largest increase in blood pressure. A high concentration of sex steroids seems to be associated with decreased sleep latency and a decreased time spent awake [17]. An increased frequency of restless legs syndrome during pregnancy has been linked to a low level of serum ferritin [14]. Backache, fetal movements and a more frequent urge to urinate may also cause disturbances in sleep [2], [10].

The aim of the present study was to use mothers' self-reports to determine the quantity and quality of sleep as well as the frequencies of sleep disturbances before, during and after pregnancy.