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Mothers’ Restless Nights Before Birth Linked to Faster Baby Weight Gain After 6 Months
In A Nutshell
- Toddlers whose mothers slept very poorly late in pregnancy were estimated to weigh up to 1.7 pounds more at 17 months.
- These babies started slightly lighter, then gained faster after six months.
- The link was clearer in boys and full-term babies and not explained by feeding habits.
- The study cannot prove cause and effect.
At 17 months old, toddlers whose mothers slept very poorly in late pregnancy were estimated to weigh up to 1.7 pounds more than toddlers whose mothers slept better, according to a study of 645 mother-child pairs in Los Angeles. Those sleepless final weeks of pregnancy may do more than leave a mother exhausted. They may be tied to how quickly her baby grows over the first two years of life.
Babies whose mothers slept the worst actually started out slightly lighter than their peers during the first six months, then caught up and passed them. That fast gain matters because rapid weight gain in infancy has been identified as a predictor of overweight and obesity later in childhood. Researchers consider the first two years of life a critical window for growth, one that can set the stage for long-term health.
Published in the American Journal of Preventive Medicine, the research focused on low-income Hispanic families, a group with higher obesity risk than other racial and ethnic groups in the U.S. Pregnancy sleep and child growth had not been extensively studied in this population.
Poor Sleep During Pregnancy Linked to Heavier Toddlers Among 645 Los Angeles Families
Researchers drew on a Los Angeles pregnancy project called the Maternal and Developmental Risks from Environmental and Social Stressors study. Mothers averaged 28.8 years old at enrollment, about 81% identified as Hispanic, and 51% of the children were girls.
At roughly 32 weeks of pregnancy, mothers filled out the Jenkins Sleep Scale, a four-question survey scored from 0 to 20, with higher numbers meaning worse sleep. A score of 12 or higher counts as severe sleep disturbance. Mothers averaged 8.0, a mild to moderate level, and about 26% scored 12 or above. Of 805 children with growth records, 645 had mothers who answered the sleep survey, and those families looked much like all 1,065 women enrolled in the project.
Each child’s weight came from medical records or checkups between birth and age 2, adding up to more than 6,000 measurements. Researchers accounted for factors such as the mother’s age, her weight before pregnancy, her education, and her race and ethnicity, plus the child’s sex and whether the baby arrived early.
Rather than sorting mothers into two camps, the team used a statistical model to estimate the weight of a typical child at each age. One child had a mother who scored 16, worse than about 90% of mothers in the group. The other had a mother who scored 4, better than about 75% of them. By age 1, the first child was about 347 grams heavier, roughly three-quarters of a pound. The gap peaked at 17 months at about 750 grams, or 1.7 pounds, and the difference held up from 11 to 22 months. Results stayed similar in extra checks, including when the analysis covered only children with at least two measurements or only medical-record data.
Baby Weight Gain Link Was Stronger in Boys and Full-Term Babies
Boys showed the pattern more clearly. Among the 316 boys, those whose mothers had very poor sleep were estimated to weigh about 651 grams more, about 1.4 pounds, between 11 and 21 months. Girls grew quickly early on, then leveled off after their first birthday, and weights stayed closer together across sleep groups. Animal research offers a possible hint about the boys. In earlier studies, pregnant mice whose sleep was repeatedly interrupted had male offspring with higher body weight, though the authors cautioned that such models cannot fully mimic human sleep.
Babies born early, 56 in all, showed a narrower gap too. Preterm infants typically grow fast to make up for time lost in the womb, a catch-up that the authors suggested may have masked any added effect of maternal sleep.
Feeding Habits Did Not Explain the Poor Sleep During Pregnancy Link
Mothers with the worst sleep scores were more likely to stop breastfeeding sooner and introduce juice or other foods earlier. They also reported more depression symptoms and were more likely to gain too much weight during pregnancy. Even so, accounting for feeding habits, and separately for depression, left the weight pattern largely unchanged. That matches one earlier study of Mexican American families, even though other research has named breastfeeding length and early foods as obesity predictors.
Authors pointed to a few possible explanations while stressing that the study cannot confirm any of them. Fat cells form mostly in late pregnancy, so disrupted sleep could affect that process. Poor sleep might also strain a mother’s metabolic health, meaning how her body handles food and energy, or the sleep survey may partly reflect broader stress.
Sleep Checks in Prenatal Care Could Flag At-Risk Pregnancies
Because this was an observational study, meaning families were tracked rather than assigned to anything, it shows a connection but cannot prove that poor sleep caused the extra weight. Researchers still suggested adding sleep quality checks to routine prenatal care to help spot pregnancies that may need closer attention. Asking about sleep is reasonable, but until studies test whether improving a mother’s sleep changes a child’s growth, the link remains a pattern, not a prescription.
Disclaimer: This article is for informational purposes only and is not medical advice. Consult a healthcare provider with health questions.
Paper Notes
Limitations
Mothers reported their own sleep quality on the Jenkins Sleep Scale, which can introduce recall bias, partly because physical discomfort in pregnancy may make sleep problems harder to recognize. The authors said this kind of misclassification would likely be nondifferential, meaning it would tend to weaken rather than exaggerate the associations. The scale measures sleep disturbance broadly and cannot separate sleep length, interrupted sleep, or breathing-related sleep problems. Sleep was assessed once in late pregnancy, so the study cannot say whether earlier pregnancy sleep or changes over time mattered. Because the study is observational, it cannot show that poor sleep causes changes in growth. Factors not fully captured, including maternal diet, sleep disorders such as sleep apnea, broader life stress, and children’s own diet, sleep, parenting practices, and physical activity, could still influence the results. Sleep data were available for only a subset of the larger cohort, which raises the possibility of selection bias, although key demographics did not differ between the subset and the full cohort. The authors also noted that mothers who delivered early may have been less likely to complete the late-pregnancy sleep survey, which could affect the preterm findings.
Funding and Disclosures
Support came from the Maternal and Developmental Risks from Environmental and Social Stressors Center (grant numbers P50ES026086 and P50MD015705), funded by the National Institute of Environmental Health Sciences and the National Institute for Minority Health and Health Disparities. Additional support came from the Southern California Environmental Health Sciences Center (grant number P30ES007048, National Institute of Environmental Health Sciences) and the Lifecourse Approach to Developmental Repercussions of Environmental Agents on Metabolic and Respiratory health program (grant number UH3OD023287, National Institutes of Health Office of the Director ECHO Program). The authors declared no conflicts of interest.
Publication Details
Title: “Self-Reported Sleep Quality in Late Pregnancy Is Associated With Early-Childhood Growth Trajectories in Children Aged 0−2 Years in Hispanic Populations.” Authors: Xiaoran Yang, Sandrah P. Eckel, Erika Garcia, Tingyu Yang, Xinci Chen, Brendan Grubbs, Laila Al-Marayati, Claudia M. Toledo-Corral, Jill Johnston, Kathleen A. Page, Genevieve F. Dunton, Shohreh F. Farzan, Theresa M. Bastain, and Carrie V. Breton. Journal: American Journal of Preventive Medicine, published by Elsevier, 2026;000(000):108546. DOI: https://doi.org/10.1016/j.amepre.2026.108546. Corresponding author: Carrie V. Breton, PhD, School of Public Health, Washington University, St. Louis, Missouri.
