Uniplant is a single contraceptive implant intended for one year use. It contains the progestogen nomegestrol acetate. The clinical performance and the effect of its use during the first postpartum year on breastfeeding performance and growth and health of the infants were studied and compared to the findings in a parallel group who used an intrauterine contraceptive device (IUD) in a prospective, non-randomized study. This was carried out in Assiut, Egypt. Two-hundred-forty fully breastfeeding mothers asking for initiation of contraception early postpartum were assigned according to their choices into either nomegestrol subdermal contraceptive implant (Uniplant) (120 women) or intrauterine contraceptive device (CuT 380A) (120 women). The mother and infant pairs were followed up at monthly intervals during the first three months and at two-month intervals thereafter up until the first birthday of the baby. No pregnancy occurred in the two groups. Amenorrhea was significantly more prolonged in the Uniplant group than in the IUD group. There were no significant differences in net continuation rates between the two groups (88.3 versus 92.4 per 100 women, respectively). There were no significant differences between the two groups in the number of breastfeeding episodes, time of weaning, and the cumulative rates of full and partial breastfeeding. There were no significant differences between the two groups in infant weight, weight gain per day, or in infant linear growth. There were no significant differences in the incidence of important health problems affecting the infants of the two groups. However, there were seven infant deaths, six of them were in the Uniplant group. Uniplant subdermal contraceptive implants can be offered as a new contraceptive option suitable for nursing mothers.