Influence of breastfeeding and iron status on mental and psychomotor development during the first year of life.

Breastfeeding (BF) confers numerous benefits on the developing infant in both the short and the long term including psychological development, but there are multiple other factors that must be taken into account when these relationships are studied. To analyse how breastfeeding during the first 4 months of life affects infant mental and psychomotor development (MPD) at 6 and 12 months in a group of healthy infants from a Mediterranean Spanish city considering many important potential confounds. This is a longitudinal study conducted on infants from birth until the age of 12 months. A total of 154 healthy infants were evaluated by Paediatric Unit of Sant Joan University Hospital in Reus, Spain. Type of feeding, clinical history, anthropometry, iron status and mental and psychomotor development were assessed and analysed. At 4 months, 24% of infants received BF and 26% received mixed feeding (MF). Multiple Linear Regression models were applied adjusting for potential prenatal, perinatal and postnatal confounds showing that infants who received BF for at least four months presented higher psychomotor development index (PDI) at 6 and at 12 months of age. Also, gestational age and BMI at 6m were associated positively with PDI at 6 m, and haemoglobin levels at 12m and birth height were associated with PDI and MDI at 12m (respectively). In conclusion, after the adjustment of important potential confounds, BF during at least four months and adequate infant iron status are related to better psychomotor development during the first year. No associations were found between BF and mental development.