Investigators have found significant associations between longer breastfeeding duration and improved developmental outcomes in children. A large-scale cohort study was conducted in Israel and included data from more than 570,000 children and sophisticated controls for potential confounding variables through multiple analytical approaches.

Researchers found that children who were breastfed for at least 6 months exhibited fewer delays in attaining language, social, and motor developmental milestones compared to children who were breastfed for less than 6 months. The adjusted odds ratio (aOR) was 0.73 (95% confidence interval [CI] =0.71–0.76) for exclusive breastfeeding and 0.86 (95% CI = 0.83–0.88) for nonexclusive breastfeeding.

"Children who were breastfed for at least 6 months exhibited fewer delays in attaining language and social or motor developmental milestones compared with children exposed to less than 6 months of breastfeeding," the authors reported in JAMA Network Open.

The study's findings were strengthened by a within-family analysis of 37,704 sibling pairs, which showed that children who were breastfed for at least 6 months were less likely to demonstrate milestone attainment delays (odds ratio [OR] = 0.91,95% CI =0.86–0.97) or be diagnosed with neurodevelopmental conditions (OR =0.73,95% CI =0.66–0.82]) compared with their siblings who received less than 6 months of breastfeeding or were not breastfed.

The research team, led by Inbal Goldshtein, PhD, of KI Research Institute, utilized data from a national network for routine child development surveillance linked with national social insurance financial entitlements for neurodevelopmental deficiencies. This comprehensive dataset allowed researchers to control for numerous confounding variables related to both the child (gestational age, birth weight, multiple gestation, and child order) and mother (age, socioeconomic status, educational level, marital status, employment, nationality, and postpartum depression).

The study population included children born in Israel between January 2014 and December 2020 after at least 35 weeks' gestation without severe morbidity and with at least one follow-up surveillance visit at 2 to 3 years of age. The cohort was comprised of 570,532 children, of whom 291,953 (51.2%) were male, 20,642 (3.6%) were born preterm, and 38,499 (6.7%) were small for gestational age. About 52% of the children (297,571) were breastfed for at least 6 months, with 123,984 (41.7%) being exclusively breastfed.

The primary outcomes measured were delays in attainment of developmental milestones and diagnosis of prespecified neurodevelopmental conditions. The study used three analytical approaches: multivariable regression, covariate matching, and within-family analysis.

The association between breastfeeding and developmental outcomes was observed as a dose-response relationship. The odds of milestone attainment delay gradually decreased with longer breastfeeding duration, particularly in the first months of life, reaching a near plateau after 10 to12 months of breastfeeding.

While the ORs were similar for both late-preterm and early-term to postterm infants, the absolute benefit was greater among preterm children due to their higher baseline rates of developmental concerns.

The researchers noted: "The association between breastfeeding duration and developmental outcomes was similar for late-preterm and early-term to postterm infants. While the ORs were similar, the absolute difference depended on the baseline rates.  Neurodevelopmental conditions were more common among preterm children, yielding greater absolute benefits."

This study adds to the growing body of evidence supporting current WHO recommendations for exclusive breastfeeding for the first 6 months of life, followed by continued breastfeeding alongside complementary foods for up to 2 years or beyond.

The authors concluded: "In this cohort study, exclusive or longer duration of breastfeeding was associated with reduced odds of developmental delays and language or social neurodevelopmental conditions. These findings may guide parents, caregivers, and public health initiatives in promoting early child development."

Disclosures can be found in the study.