Background:  Non-breastfeeding women are exposed to a greater risk of unwanted pregnancy. We studied the incidence of a new pregnancy among HIV-infected women followed postpartum over 24 months after a PMTCT intervention combining short-course antiretrovirals (scARVs) and alternatives to prolonged breastfeeding, in a cohort in Abidjan, Côte d’Ivoire.

Methods: All HIV-infected women included in the ANRS 1201-1202 Ditrame-Plus project from March 2001 to July 2003, age <49 years, who received a scARV regimen (ZDV+single-dose nevirapine+/-3TC), who delivered a live birth, and initiated one of the two infant feeding options offered (replacement feeding or exclusive breastfeeding during 4 months) were included. Contraceptive methods were promoted free of charge according to the infant feeding option. The outcome was the occurrence of the first new pregnancy during the 24 months of follow-up; the reported date of last menstrual period and the gestational age assessed by ultrasound were used to estimate when this pregnancy started. The 12 and 24-month probability of occurrence of a new pregnancy was estimated using a Kaplan-Meier method. We analyzed factors associated with the occurrence of a new pregnancy in a Cox model analysis conditional on the infant feeding option implemented at birth.

Results: Overall, 724 women were included, 332 (46%) initiated replacement feeding, and 392 (54%) breastfeeding. Among formula feeders, 78.1% used a contraceptive method vs. 77.5% among breast-feeders (p=0.87). Over the 24-month period, 79 new pregnancies occurred. The 12-month incidence of a new pregnancy was similar between the two groups: 4.4% (95% confidence interval [CI]: 2.7-7.2%) in breast-feeders and 4.1% (CI: 2.4-7.0%) in formula-feeders. Factors independently associated with the 12-month occurrence of pregnancy were an advanced WHO clinical stage 3-4 and the death of the last-born child. The 24-month incidence of a new pregnancy was significantly lower in formula feeders than in breast-feeders, 10.0% vs. 16.5% (p=0,003, adjusted HR: 0.5; CI: 0.3-0.9). Other factors significantly associated with the 24-month incidence of pregnancy were the follow-up clinic, the number of live-born children and the death of the last born child.

Conclusions: Replacement feeding is not responsible of a greater incidence of pregnancy in this urban West African population. Our results highlight the public health importance to deliver appropriate family planning services for HIV-infected women.