IntroductionDuration of breast feeding and factors possibly affecting duration were studied in a population of 2174 newborn infants, with gestational age of >37 weeks, who were born in the Department of Obstetrics and Gynaecology at the University of Florence Hospital between November 15, 1997, and November 14, 1998.Patients and MethodsNine hundred mothers agreed to participate in the study. Five questionnaires were completed at the end of the 1st, 3rd, 6th, 9th, and 12th postpartum month. These dealt with infant feeding practices, including breast feeding during the previous week. Breast feeding duration was defined as short (1 month); medium-short (>1 month–<3 months); medium (>3–<6 months); medium-long (>6–<9 months), and long (>9 months).ResultsThe authors found that 76.3%, 64.7%, 42.3%, 26.4%, and 17% of mothers were still breast feeding at 1, 3, 6, 9, and 12 months after delivery, respectively. The multivariate analysis of the correspondence shows that lack of breast feeding is associated with a birth weight of less than 3000 g, a low level of maternal education, and maternal profession as a housewife or blue collar worker in the commercial sector. A period of breast feeding defined as short or medium-short is associated with mothers who smoke, primiparous mothers, and absence of maternal allergy. The survival curves highlight how the single factor of smoking is an element that leads to a significant difference in the duration of breast feeding. The multiple Cox regression analysis shows a significant negative influence associated with birth weight of less than 3000 g, maternal smoking, and first parity. Above all, among low–birth-weight infants of mothers who smoke, there is a strong correlation with a shorter duration of breast feeding.DiscussionThere is still a need for programs that support and encourage breast feeding, focusing particularly on mothers with a low level of education who give birth to a low-weight infant, primiparous mothers, and smokers.