Background:  To reduce mother-to-child HIV transmission (MTCT) in resource-poor settings, the World Health Organization (WHO) has recommended exclusive breastfeeding for 6 months followed by rapid weaning when alternatives are not safe or sustainable. Traditionally in many of these settings, complementary feeding begins as early as 2 weeks after delivery. The Kisumu Breastfeeding Study (KiBS) is an ongoing trial of maternal ART from 34 weeks’ gestation to 6 months post partum in conjunction with exclusive breastfeeding and weaning during the sixth month.

Methods:  Prior to enrolment, potential participants were counseled on infant feeding options. Those who opted for exclusive breastfeeding for 6 months and met eligibility criteria were enrolled at 34 weeks’ gestation. Mother and infant were followed for 2 years. Infant feeding and general nutrition counseling began at 35 to 37 weeks’ gestation using WHO infant feeding guidelines. An infant-feeding questionnaire was administered at study visits between delivery and 6 months to assess adherence to exclusive breastfeeding and after 6 months to assess compliance with cessation of breastfeeding. Women with HIV-infected infants were not aggressively encouraged to stop breastfeeding.

Results:  The study had a total of 504 live births, of these 95% (478) were still in the study at 6 months. Among these 478, 98 (21%) were mixed fed before 5 months of age. Successful weaning by the end of 6 months occurred in 86% (409) of the 478 infants and continued past 6 months in 14% (69). Among the 69 mothers who continued breastfeeding past 6 months, 29% (20) had HIV-infected infants and 12% (8) were on ART and 59% (41) did so for other reasons in the absence of ART.

Conclusions:  This analysis demonstrates that even in the context of a prevention of MTCT study with regular counseling on the benefits of exclusive breastfeeding and cessation at 6 months, many women mixed fed before 5 months and among those that continued breastfeeding beyond 6 months, 59% did so in the absence of ART. Further exploration of the factors that encourage an HIV-infected woman to mix feed early and to continue breastfeeding after counseling to the contrary, and thus putting her infant at increased risk of HIV infection is necessary. It is also important to assess how the WHO recommendations are conveyed and potentially design more appropriate messages to target the individuals and institutions that affect how a woman chooses to feed her infant.