Longer breastfeeding duration, better child development? Evidence from a large-scale survey in China.

• We apply generalized propensity score matching method and instrumental variable method to explore the relationship between breastfeeding duration and child development. • The relationship is relatively stable and presents a U shape, with the optimal breastfeeding duration (6–10 months) promoting children's early behavior performance. • Breastfeeding longer than the optimal duration delays child development. • The optimal duration of breastfeeding had a greater positive effect on children from disadvantaged backgrounds. • The conclusions of this paper have obvious practical value for the policy of child development strategies and parenting practices. Based on a large-scale survey in China, we use the generalized propensity score matching method and instrumental variable method to explore the effect of breastfeeding duration on child development, and find that there is a relatively stable "U" relationship between breastfeeding duration and children's early behavioral performance, with the optimal breastfeeding duration (6–10 months) promoting children's early behavioral performance. However, more than the optimal breastfeeding duration will delay child development. We further find that the effect of breastfeeding duration on child development varies among different groups. There is evidence that the optimal breastfeeding duration has a greater positive effect on children from disadvantaged backgrounds. The conclusions of this paper have obvious practical value for the policy of child development strategies and parenting practices. Given the importance of early child development, there should be a reasonable breastfeeding duration, and the feeding interventions for disadvantaged children can bring higher returns. [ABSTRACT FROM AUTHOR]