Maternal weight before pregnancy may shape children’s development

A large Korean study links underweight and obesity before pregnancy to early developmental delays, while suggesting that the risks to cognitive development may begin as early as the threshold for overweight.

Study: Maternal pre-pregnancy BMI and neurodevelopmental outcomes in children aged 18–36 months: a nationwide cohort study in Korea.. Image Credit: Fast-Stock/Shutterstock

A large population-based study from South Korea was published in the journal scientific report This highlights that the risks to early childhood development may extend beyond obesity alone.

Analyzing data from more than 250,000 mother-child pairs, researchers found that maternal underweight and obesity were linked to higher risks across multiple developmental domains, while maternal overweight was specifically associated with increased cognitive delays at 18 to 24 months.

In particular, the strongest effects were seen in children of severely obese mothers, with impacts on cognition, language and self-care skills, underscoring the importance of preconception health for development during the first three years of life.

Maternal pre-pregnancy BMI and child development

Maternal weight before pregnancy plays an important role in shaping both pregnancy outcomes and long-term baby health. Obesity before pregnancy increases the risk of complications such as preeclampsia, preterm birth, and cesarean delivery, as well as puts the offspring at risk for cardiometabolic disorders and developmental challenges.

Emerging evidence links maternal body mass index (bmi) for early neurodevelopment, yet major questions remain.

The effects of maternal underweight are less clearly defined; Findings are inconsistent across developmental regions, and most studies focus on Western populations.

These gaps limit comprehensive understanding and highlight the need for larger, population-based analyzes in different settings.

Korean group study design and methods

In this retrospective cohort study, researchers explored the effect of maternal pre-pregnancy body mass index (bmi) on early neural development among children in Korea.

The team analyzed data from 258,367 mother-infant pairs drawn from the National Health Screening Program for Infants and Children (NHSPIC) and the National Health Insurance Service-Health Screening Cohort (NHIS-HEALS), covering births during 2014-2021.

All children underwent the Korean Developmental Screening Test (K-DST) at two time points: 18 to 24 months and 30 to 36 months. The test evaluated six domains: gross and fine motor skills, cognition, language, sociability, and self-care.

Researchers classified maternal bmi Based on health examination records obtained within 3 years before delivery, as per Asia-Pacific norms. He published the International Classification of Diseases, Tenth Revision (icd-10)-coded insurance claims data.

To minimize baseline differences between the groups, the team used propensity score weighting through multivariable logistic regression. They then estimated the frequency of developmental delays and calculated relative risks (RRS) Using generalized linear models, children of normal weight mothers are used as a comparison group.

Analyzes were adjusted for several potential confounders. These include maternal age, birth characteristics, neonatal complications, and perinatal factors, but the observational design means that the findings show an association rather than prove that maternal bmi There was a direct delay in development.

Maternal BMI and Child Neurodevelopment Findings

Of the 258,367 mother-child pairs analyzed, 60% of mothers belonged to the healthy weight range, 12% were underweight, 13% were overweight, 12% were obese and 3% were severely obese. As bmi increased, maternal comorbidities such as hypertension and diabetes became more common.

However, depression disproportionately affects underweight, obese, and severely obese mothers. higher maternal bmi It is also associated with higher birth weight, increased admissions to neonatal intensive care, and fewer vaginal deliveries.

From 18 to 24 months of age, a slight increase in the risk of developmental delays was seen in children born to underweight mothers, while a greater increase was seen in children born to mothers with obesity, especially severe obesity.

The strongest effect was seen in those born to mothers with severe obesity, where the risk for self-care more than doubled (RR2.0) and almost double for cognition (RR1.98), with high rates of language delay (RR1.5).

Interestingly, children of overweight mothers also showed higher cognitive delays at this stage. By 30 to 36 months, the excess risk associated with low maternal weight was largely reduced, suggesting partial developmental catch-up, whereas delays continued in children exposed to maternal obesity, following clear dose-response patterns in all assessed domains.

These findings point to specific underlying mechanisms. Transient nutritional deficiencies in underweight mothers may aid postnatal development, whereas obesity-related inflammation, metabolic disruption, and hormonal imbalance are likely to have long-lasting effects on the developing brain.

Together, the results strengthen the growing evidence that maternal weight, especially excess weight, is associated with early neurodevelopmental differences that may persist into childhood, although residual confounding from socioeconomic, educational, genetic, home, and postnatal factors cannot be excluded.

Preconception weight and public health implications

These findings extend the interaction beyond obesity, suggesting that neurodevelopmental risk may begin as early as overweight, particularly for cognitive delays in early childhood. This has immediate clinical and public health implications.

daily routine bmi Screening and targeted pregnancy counseling should extend to all overweight women, not just obese women. Early identification of at-risk mother-child pairs may allow timely monitoring and intervention during critical developmental periods.

Looking ahead, more accurate modeling approaches and longitudinal studies are needed to define the optimal bmi Limits and track developmental trajectories over time. Integrating gestational, socioeconomic, and perinatal factors will further refine risk assessment.

The authors also noted important limitations, including reliance on developmental investigations rather than comprehensive clinical diagnosis, absence of data on gestational weight gain, bmiinability to capture body composition or micronutrient status, and potential selection bias because the final group represented only a subgroup of all births during the study period.

As overweight and obesity rates continue to increase globally, these insights provide an important opportunity to change prevention strategies before pregnancy begins, potentially improving neurodevelopmental outcomes at the population level with lasting benefits for future generations.