Does cesarean delivery impact infant weight gain and adiposity over the first year of life?

Background Potentially driven by the lack of mother-to-infant transmission of microbiota at birth, cesarean delivery has been associated with higher risk of offspring obesity. Yet, no studies have examined when delivery-mode differences in adiposity begin to emerge. In this study, we examine differences in infant weight and adiposity trajectories from birth to 12 months by delivery mode. Methods From 2013 to 2015, we recruited pregnant women into the Nurture Study and followed up their 666 infants. We ascertained maternal delivery method and infant birth weight from medical records. We measured weight, length, and skinfold thicknesses (subscapular, triceps, abdominal) when infants were 3, 6, 9, and 12 months of age. The main outcome, infant weight-for-length z score, was derived based on the WHO Child Growth Standards. We used linear regression models to assess the difference at each time point and used linear mixed models to examine the growth rate for infant weight and adiposity trajectories. We controlled for maternal age, race, marital status, education level, household income, smoking status, maternal pre-pregnancy body mass index, and infant birth weight. Results Of the 563 infants in our final sample, 179 (31.8%) were cesarean delivered. From birth to 12 months, the rate of increase in weight-for-length z score was 0.02/month (p = 0.03) greater for cesarean-delivered than vaginally-delivered infants. As a result of more rapid growth, cesarean-delivered infants had higher weight-for-length z score (0.26, 95% CI: 0.05, 0.47) and sum of subscapular and triceps (SS + TR) skinfold thickness (0.95 mm, 95% CI: 0.30, 1.60)-an indicator for overall adiposity-at 12 months, compared to vaginally-delivered infants. Conclusions Compared to vaginal delivery, cesarean delivery was associated with greater offspring rate of weight gain over the first year and differences in adiposity that appear as early as 3 months of age. Monitoring cesarean-delivered infants closely for excess weight gain may help guide primordial prevention of obesity later in life.