Studies have suggested that higher maternal pregnancy body weight index (BMI) is associated with adverse, long-term offspring outcomes, such as psychiatric disorders, cognitive disabilities, and congenital obesity. However, no established evidence of this association is present. This study aims to examine the association of maternal prepregnancy BMI with fetal growth and neonatal thalamic brain connectivity.

This prospective longitudinal cohort study included a total of 129 adolescent and young adult women aged 14-19 years who received routine prenatal care and had no major health problems. Exposures to maternal pregnancy BMI were put into consideration. The primary outcomes of the study were fetal growth, estimated fetal weight, and neonatal functional connectivity.

Ultrasonographic data on 105 of 109 women were available for analysis. The findings suggested that maternal pregnancy BMI was positively associated with estimated fetal weight but not with the fetal head circumference. A subsample of 45 infants with magnetic resonance imaging data was also considered, which indicated that maternal prepregnancy BMI was associated with global connectivity in the left thalamus. The findings also suggested that higher maternal BMI was correlated with local thalamic connectivity.

The research concluded that maternal pregnancy BMI was directly associated with the regulation of body weight and thalamic function in the offspring.