Sleep duration of lactating mothers and its relationship with feeding pattern, milk macronutrients and related serum factors: A combined longitudinal cohort and cross-sectional study

Abstract

ObjectiveInsufficient sleep is common in postpartum mothers. The main objectives of this study are to explore the sleep duration among Chinese lactating mothers and preliminarily investigate the relationship between sleep duration and feeding pattern. The secondary objectives are to investigate the relationships between sleep duration and milk macronutrients and between maternal-related indicators, including melatonin (MT), growth hormone (GH), ghrelin (GHRL), glucagon-like peptide-1 (GLP-1), prolactin (PRL), and cholecystokinin (CCK).MethodsThe present study comprises a longitudinal and a cross-sectional cohort from December 2019 to December 2021. Postpartum lactating women living in Shanghai were recruited through online and offline recruitment. The subjects were included in the longitudinal cohort or cross-sectional study based on their lactation period at the time of recruitment. The longitudinal cohort included a total of 115 mothers. Human milk and feeding pattern were measured and collected at 2–4 months and 5–7 months postpartum. At four predetermined follow-up time points, data on sleep duration was collected (at the time of recruitment, 2–4 months postpartum, 5–7 months postpartum, and 12–17 months postpartum). The cross-sectional study included 35 lactating mothers (2–12 months postpartum) who reported their sleep duration and provided blood samples. Mid-infrared spectroscopy (MIRS) method was used to analyze the macronutrients of breast milk, while MT, GH, GHRL, GLP-1, PRL, and CCK in maternal blood were determined by ELISA.ResultsThe maternal sleep duration before pregnancy was 8.14 ± 1.18 h/d (n = 115), 7.27 ± 1.31 h/d (n = 113) for 2–4 months postpartum, 7.02 ± 1.05 h/d (n = 105) for 5–7 months postpartum, and 7.45 ± 1.05 h/d (n = 115) for 12–17 months postpartum. The incidence of insufficient sleep (<7 h/d) before pregnancy (12.17%) was significantly less than at any follow-up time after delivery (vs. 2–4 months postpartum, χ2 = 10.101, p = 0.001; vs. 5–7 months postpartum, χ2 = 15.281, p < 0.0001; vs. 12–17 months postpartum, χ2 = 6.426, p = 0.011). The percentage of insufficient maternal sleep was highest at 5–7 months postpartum (34.29%). No significant difference was found between the incidence of insufficient sleep at 5–7 months postpartum, 2–4 months postpartum (29.20%, χ2 = 0.650, p = 0.420), and 12–17 months postpartum (25.22%, χ2 = 2.168, p = 0.141). At 2–4 months postpartum, the frequency of formula feeding per day is related to reduced maternal sleep duration (Standardization coefficient β = −0.265, p = 0.005, Adjusted R2 = 0.061). At 2–4 months and 5–7 months postpartum, the relationship between macronutrients in breast milk and the mother's sleep duration was insignificant (all p > 0.05). Other than the positive correlation found between maternal GHRL and sleep duration (r = 0.3661, p = 0.0305), no significant relationship was observed between sleep duration and other indexes (all p > 0.05).ConclusionsPostpartum mothers generally sleep less, but there is no correlation between insufficient sleep and the macronutrient content of breast milk. Formula feeding may be related to the mother's sleep loss, while breastfeeding (especially direct breastfeeding) may be related to increased maternal sleep duration. The findings suggest that sleep duration is related to maternal serum GHRL. More high-quality studies are needed to clarify the mechanism of these findings and provide a solid theoretical basis and support references for breastfeeding.

Parents’ Sleep Multi-Trajectory Modelling from 3 to 36 Months Postpartum in the SEPAGES Cohort

“… 37 Breastfeeding Chinese mothers also reported about 7h00 of NSD from 2 to 7 months postpartum, and about 7h30 at 12 to 17 months. 38 Mean paternal NSD was stable, about 8 hr, from 3 to 36 months postpartum. It was also longer in our study than in other studies: the mean NSD was 6h11 at 7 weeks postpartum among US fathers 9 and about 7h20 by subjective and objective measures among Canadian fathers at 6 months postpartum.…”

“…Although most parental sleep studies measured maternal or paternal sleep by sleep diaries 19 , 36 or validated questionnaires, 9 , 10 self-reported sleep based on bedtime and wake-up time is widely used in epidemiological studies of sleep in general populations. 37 , 38 We did not collect data on the frequency and duration of parental night waking, but we considered the frequency of the child’s night waking in a sensitivity analysis showing that parental NSD was low from 3 to 18 months postpartum but remained longer than the parental sleep duration reported in other populations. 9 , 19 , 38 , 39 Another explanation for the observed long sleep durations may be the specificity of the study population.…”

“… 37 , 38 We did not collect data on the frequency and duration of parental night waking, but we considered the frequency of the child’s night waking in a sensitivity analysis showing that parental NSD was low from 3 to 18 months postpartum but remained longer than the parental sleep duration reported in other populations. 9 , 19 , 38 , 39 Another explanation for the observed long sleep durations may be the specificity of the study population. The included fathers and mothers had high socioeconomic status, low BMI and long breastfeeding duration, which may reflect families that are more likely to follow healthy lifestyle recommendations, 41 including sleep recommendations.…”

“…Fifth, sleep was subjectively assessed through self-questionnaires. However, to minimize recall bias, questions were asked at each time point on current bedtime and wake-up time during both weekdays and weekend days, as commonly used in epidemiological studies 37 , 38 as well as questions on naps and subjective sleep loss reflecting their own perception of their sleep. Lastly, we only included heterosexual couples.…”

Maternal Sleeping Problems Before and After Childbirth - A Systematic Review

“… 62 Ruan et al investigated the relationship between sleep duration and breast milk macronutrient concentrations but did not find a significant correlation. 15 A study by Astbury et al has demonstrated that breastfeeding itself is not associated with lower quality and quantity of nocturnal sleep, but a higher number of nighttime feeds is a strong predictor of shorter sleep duration and poor sleep quality. 63 …”