New research links poor maternal sleep in late pregnancy to a striking growth pattern in early childhood.
Children of mothers with the worst sleep quality weighed less in the first six months of life, then gained faster and were heavier by ages 1 and 2.
The observational study, published in the American Journal of Preventive Medicine, followed 645 mother-child pairs from the MADRES cohort in Los Angeles.
About 26 percent of the mothers reported poor sleep on the Jenkins Sleep Scale, a standard questionnaire on sleep problems.
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At age 1, children of the poorest-sleeping mothers weighed roughly 347 grams (about 12 ounces) more than children of mothers who slept well. By 17 months the gap widened to about 751 grams, close to 1.7 pounds. The pattern was strongest in boys and in babies born at term.
A reversal that starts before birth
The reversal is what stands out. Poor maternal sleep was tied to lower infant weight from birth through six months, then to accelerated catch-up afterward.
Rapid weight gain in the first two years is one of the most consistent early predictors of later childhood obesity.
"Our research supports the notion that exposures during critical developmental windows of pregnancy can program offspring health," senior author Carrie V. Breton said. Breton is a professor at Washington University in St. Louis and holds an adjunct appointment at USC's Keck School of Medicine.
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Why late pregnancy sleep may matter
The concept of fetal programming, also called the developmental origins of health and disease, describes how the intrauterine environment can shape a child's long-term metabolism.
Sleep influences hormones that regulate appetite, blood sugar, and inflammation. Disturbed sleep late in pregnancy may nudge those systems in ways the baby carries into infancy.
Poor sleep in pregnancy is common but often untreated. A separate 2026 MADRES analysis from the same research team, published in Environmental Research, found mental health, air pollution, noise, and neighborhood stressors among the strongest predictors of poor sleep in late pregnancy.
Lead author Xiaoran Yang said poor sleep during pregnancy is common and often overlooked in routine prenatal care.
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Yang added that tracking sleep at prenatal visits could be a simple step toward healthier growth in early childhood.
Practical steps that may help
The National Sleep Foundation estimates that at least 50 percent of pregnant women experience insomnia.
The organization's sleep hygiene guidance offers concrete steps expectant mothers can try before considering medication.
Keep the bedroom cool, dark, and quiet, and use the bed only for sleep. Stick to a consistent bedtime and schedule naps earlier in the day. Wind down with a warm bath or a book, and put screens away at least an hour before bed.
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Cut caffeine, spicy foods, and heavy meals in the evening. Taper fluids before bed to reduce nighttime bathroom trips. Try to get regular exercise earlier in the day.
Pregnant women with persistent insomnia, loud snoring, or daytime exhaustion should raise it with their obstetrician.
Some over-the-counter sleep aids, including valerian root and melatonin, lack safety data during pregnancy and should not be used without medical guidance.
The findings are observational and cannot prove that poor sleep caused the growth pattern the researchers observed.
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The authors call for sleep quality to be assessed at routine prenatal visits, alongside the standard checks already done in every trimester.
This article is made and published by Mie Hermansen, who may have used AI in the preparation.