Exclusive Breastfeeding, Family Context, and Executive Function in Early Childhood: A Cross-Sectional Study in Khon Kaen, Thailand

Exclusive breastfeeding (EBF) for the first six months of life is recommended by the World Health Organization, but its association with executive function (EF) in early childhood remains uncertain. This study examined whether EBF during the first six months of life and breastfeeding duration were associated with EF in early childhood and explored relevant child and family characteristics. We conducted an analytical cross-sectional study among 316 children aged 24–35 months attending the Well-Child Clinic, Health Promotion Hospital, Regional Health Promotion Center 7 Khon Kaen, Thailand. EF was assessed using the Minnesota Executive Function Scale (MEFS). The continuous MEFS Standard Score was used as the primary outcome and analyzed using multivariable linear regression. Post hoc exploratory analysis using the 55th percentile threshold and sensitivity analysis using the normative 50th percentile were also conducted. In the primary analysis, EBF was not statistically significantly associated with the MEFS Standard Score (adjusted β = −0.96, 95% CI: −2.13 to 0.21; p = 0.108). Child age was inversely associated with the MEFS Standard Score (adjusted β per 1-month increase = −0.29, 95% CI: −0.46 to −0.11; p = 0.002), whereas maternal education at the bachelor’s degree level or above was positively associated with EF (adjusted β = 2.44, 95% CI: 1.18 to 3.71; p < 0.001). Family functioning was not statistically significantly associated with EF in the primary continuous-score analysis (overall p = 0.319). The absence of a statistically significant association between EBF and EF was consistent across the alternative categorical outcome definitions. In contrast, the association with family functioning was only observed in the post hoc 55th percentile analysis and was not robust across outcome definitions. Breastfeeding duration as a continuous measure was not statistically significantly correlated with the MEFS Standard Score. In the post hoc exploratory analysis using the 55th percentile threshold, breastfeeding for >0 to 6 months was associated with higher odds of higher EF performance compared with no breastfeeding, whereas breastfeeding for >6 months was not. This pattern did not indicate a consistent dose–response association. These findings provide no statistically significant evidence of an association between EBF and EF in this sample, while maternal education was associated with EF performance. The findings regarding family functioning should be regarded as exploratory and hypothesis-generating.