Breastfeeding Intensity and Duration and Growth Trajectories in GDM Exposed Infants: The SWIFT Study

Background: Whether breastfeeding intensity, the relative amount of breastfeeding versus formula across the first year, relates to growth trajectories among infants exposed to gestational diabetes (GDM) in utero is unknown. Objective: To identify growth trajectory patterns and associations with breastfeeding intensity among infants exposed to GDM. Methods: SWIFT Offspring cohort (2009–2011) singleton, GDM-exposed infants (n = 435) born at a Kaiser Permanente Northern California hospital. Monthly summed lactation intensity ratio (sumLIR, proportion of breastfeeding versus overall feeds over 7 days). Latent class mixed models for weight-for-age (WAZ), length-for-age (LAZ), and weight-for-length (WLZ) z-scores, and skinfold thicknesses (triceps, subscapular, and sum of skinfolds). Multinomial logistic regression related sumLIR to growth trajectories. Results: A higher sumLIR throughout the first year was associated with lower odds of class membership in trajectories with accelerated growth patterns for WLZ from early infancy (1-mo OR: 0.11, 95% CI 0.02, 0.54) to 1 year (12-mo OR: 0.84, 95% CI 0.75, 0.95), as well as a lower likelihood of having accelerated WAZ growth after 6-months (12-mo OR: 0.91, 95% CI 0.84, 0.98), but not skinfold trajectory classes. Conclusions: Higher sumLIR was associated with more favourable growth trajectories, suggesting that continued breastfeeding, even when combined with infant formula, may benefit growth among GDM-exposed infants.