Maternal genetic liability for neuroticism and breastfeeding intention, initiation, and maintenance

Background. Successful breastfeeding and good maternal mental health are key to long term health of mothers and children and are globally recognised health goals. However, relationships between maternal mental health and breastfeeding outcomes are complex, with evidence of bi-directional effects complicated by culturally specific residual confounding and selection bias. Aim. To examine, for the first time, associations between maternal genetic liability for neuroticism (underlying trait linked to depression and anxiety over the lifespan) and breastfeeding intention, initiation, and maintenance. Methods. We used data from the Avon Longitudinal Study of Parents and Children (ALSPAC) prospective birth cohort. Maternal genotype data was used to create polygenic scores (PGS) for neuroticism and educational attainment. Mothers self-reported breastfeeding intentions at 32 weeks’ gestation, breastfeeding initiation within the first week after birth, and maintenance of breastfeeding to 6 months post birth. We examined associations between maternal genetic liability for neuroticism and breastfeeding outcomes using unadjusted logistic regression models (max. n=4997), and models that were adjusted for maternal PGS for educational attainment, and the other breastfeeding variables (intention, initiation, maintenance, max. N=4765). Results. In mutually adjusted models, there was strong evidence that genetic liability for neuroticism was associated with lower odds for breastfeeding maintenance (OR=0.89, 95%CI=0.83-0.94, p<0.001) specifically, with no evidence for independent associations with intention or initiation. That is, mothers with higher genetic liability for neuroticism were less likely to maintain breastfeeding to 6 months postpartum. This association remained when adjusting for maternal PGS for education, where a similar pattern was observed; genetic liability for education was most strongly linked to breastfeeding maintenance. Conclusions. The specificity of links between neuroticism and maintenance of breastfeeding could direct targeting of efforts to support women with emotional difficulties in maintaining breastfeeding. This is important because currently most efforts to support breastfeeding women focus on intention and initiation.