Progestogen-only contraceptives during lactation: I. Infant growth. World Health Organization Task force for Epidemiological Research on Reproductive Health; Special Programme of Research, Development and Research Training in Human Reproduction.

Growth, development and health of infants whose mothers used progestogen-only contraceptives during lactation were examined in a prospective, non-randomized study carried out in seven centres in five countries (Egypt, Thailand, Kenya, Chile and Hungary). The results on growth are reported here. Breastfeeding women requesting effective contraception were admitted to the study at six weeks postpartum. Infants of acceptors of progestogen-only methods (pill, DMPA, NET-EN or NORPLANT implants) and non-hormonal methods (IUD, barrier methods or sterilization) formed the study groups. The follow-up was at monthly intervals until the end of the first postpartum year. Participating in the study were 2466 mother-infant pairs. The mean duration of exclusive breastfeeding varied from 68 to 159 days, but did not differ significantly between study groups within centres. In anthropometric measures (weight, arm circumference and triceps skinfold), the mean rates of change varied over time as expected, and across the centres. However, there were very few statistically significant differences in these rates of change between groups within centres. Since a large number of statistical comparisons were made, and there was no consistency either across centres, over time, or in the direction of the differences, we conclude that in this study, the progestogen-only contraceptives used during lactation did not adversely affect infant growth.