Perinatal & Pediatric
Grandmaternal breastfeeding and neurodevelopmental disorders in third-generation children of the Nurses’ Health Study II Jingyuan Xiao* Jingyuan Xiao Gyeyoon Yim Tormod Rogne Andrew Thomas DeWan Jorge E. Chavarro Marc G. Weisskopf Zeyan Liew
The interest in studying multigenerational effects on neurodevelopment is growing, yet the influence of grandmaternal breastfeeding remains unexplored. We evaluated whether grandmaternal breastfeeding during the mothers’ infancy was associated with grandchildren’s autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) risk.
We analyzed 25,901 grandmother-nurse (mother)-child triads who participated in the Nurses’ Health Study II since 1989 and the Nurses’ Mothers’ Cohort Study in 2001. We estimated OR and 95% CI for grandchildren’s ASD (reported in 2005 and 2009 by the nurses) and ADHD (reported in 2005 and 2013) based on grandmaternal breastfeeding status, duration, and introduction of supplemental feeding (reported by the grandmothers), adjusting for grandmaternal socioeconomic (e.g., education, occupation, race), health-related, and life-style factors (e.g., age at delivery, smoking), as well as nurses’ parity and grandchild’s birth year. We examined potential effect modifications by the nurses’ breastfeeding and grandchild’s sex. Sensitivity analyses were conducted, such as restricting to grandchildren born 1989–1999 to consider potential insufficient follow-up for later diagnoses.
In this cohort, 56.6% of the grandmothers breastfed their daughter; grandchildren’s ASD (OR = 0.92, 95% CI = 0.69, 1.21) and ADHD (OR = 1.06, 95% CI = 0.95, 1.19) were not associated with grandmaternal breastfeeding. The associations remained null when evaluating breastfeeding duration and whether breastfeeding was supplemented with formula. There was no evidence of effect modification by the nurses’ breastfeeding or the grandchild’s sex. Results did not change in sensitivity analyses.
Grandmaternal breastfeeding during the mother’s infancy was not associated with ASD or ADHD risk in grandchildren. Our study did not support a protective effect of breastfeeding on neurodevelopmental disorders in the subsequent generation, but further replication is warranted.