Preconception health trajectories and birth weight in a national prospective cohort

This study was designed to assess the relationship between birth weight and prospectively measured trajectories of preconception health across adolescence and young adulthood in a diverse national cohort of young adult women.

Data came from Waves I (1994-1995), III (2001-2002), and IV (2007-2008) of the National Longitudinal Study of Adolescent Health. Eligibility was restricted to all the singleton live births (n = 3,436) to female participants occurring between the Wave III (ages 18-26 years) and Wave IV (ages 24-32 years) interviews. Preconception cigarette smoking, overweight/obesity, adequate physical activity, heavy alcohol consumption, and fair/poor self-rated health were measured in adolescence (Wave I) and early adulthood (Wave III) and combined into four-category variables to capture the timing and sequencing of exposure. The outcome measure, birth weight, was classified as low (<2,500 g), normal (2,500-4,000 g), and macrosomic (>4,000 g).

Multinomial logistic regression results indicated that adult-onset overweight significantly increased the odds of having a macrosomic birth (odds ratio = 1.56; 95% confidence interval = 1.02-2.38).

This study provides new evidence about the influence of maternal body mass index trajectories on offspring birth weight. Adult-onset overweight/obesity during the transition to adulthood was common in the sample and increased the odds of subsequently delivering a macrosomic infant by 56%. This finding suggests that healthy weight promotion before this transition would confer intergenerational benefits, and supports recommendations for preconception care to address overweight/obesity.