[Bottle feeding during the first month of life: determinants and effect on breastfeeding technique]

To assess incidence rate and determinants of bottle feeding during the first month of life, and its potential effects on breastfeeding technique.

A nested cross-sectional study was conducted in a contemporary cohort in the city of Porto Alegre, Southern Brazil, between June and November 2003. A total of 211 pairs of healthy mothers and infants were followed up for a month. The effect of bottle feeding on breastfeeding technique was assessed by comparing five items unfavorable to mother-infant positioning and three items unfavorable to infant latch-on; and the average number of unfavorable items between the pairs who started bottle feeding in the first month of life and those who did not. A logistic regression analysis was carried out according to a hierarchical model.

By Day 7, 21.3% of infants were bottle-fed and 46.9% were bottle-fed by Day 30. Living with maternal grandmother was associated with bottle feeding at Days 7 and 30. Maternal age <20 years, and nipple trauma at the maternity hospital were also associated with bottle feeding at Day 7. Other factors associated with bottle feeding at Day 3 were pacifier use at Day 7 and nipple trauma at Day 7. There was no association between the breastfeeding technique taught at the maternity hospital and subsequent bottle feeding. However, at Day 30, the breastfeeding technique was found to be more adequate among exclusively breast-fed infants than those who were also bottle fed.

The study results showed that bottle feeding was quite widespread in the first month of life, mainly in infants born to teenage mothers, with nipple trauma, whose maternal grandmothers were living in the same household, and who were using pacifiers. Besides the already recognized negative effects, bottle feeding may negatively affect breastfeeding technique.