Associations between maternal gestational diabetes metformin or insulin treatment and offspring growth trajectories from birth to 60 months of age: Findings from the Born in Bradford (BiB) study

To investigate the associations between gestational diabetes mellitus (GDM) metformin or insulin treatment and offspring growth trajectories from 0 to 60 months. Participants were from the Born in Bradford birth cohort study. Using covariate-adjusted multilevel linear spline models (4 splines: 0-1.6, 1.6-6, 6-17 and 17-60 months), we compared weight, height and body mass index (BMI) z-score trajectories of: (1) 76 offspring exposed to metformin (OGDM-Metformin) and 420 offspring exposed to insulin (OGDM-Insulin); (2) OGDM-Metformin and 9171 offspring not exposed to GDM (No-GDM); (3) OGDM-Insulin and No-GDM. (1) OGDM-Metformin had comparable growth trajectories to OGDM-Insulin from 0 to 60 months. (2) OGDM-Metformin had a lower mean birthweight z-score than No-GDM. OGDM-Metformin had faster changes in height z-score (0.13 [95% CI 0.026, 0.24]) from 17 to 60 months and by 60 months, had comparable mean BMI z-score to No-GDM. (3) OGDM-insulin had lower mean birthweight and height z-scores than No-GDM. OGDM-Insulin had faster changes in weight (0.32 [0.021, 0.62]) and height (0.50 [0.087, 0.91]) from 1.6 to 6 months and by 60 months, had comparable mean BMI z-score to No-GDM. GDM metformin treatment was not associated with differences in offspring growth trajectories compared to insulin treatment. Both metformin and insulin-exposed offspring had comparable BMI z-score to No-GDM by 60 months.