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Timing of Etonogestrel-Releasing Implants and Growth of Breastfed Infants: A Randomized Controlled Trial

Carmo, Lilian Sheila de Melo Pereira NP, MSc; Braga, Giordana Campos MD, PhD; Ferriani, Rui Alberto MD, PhD; Quintana, Silvana Maria MD, PhD; Vieira, Carolina Sales MD, PhD

doi: 10.1097/AOG.0000000000002092
Contents: Original Research

OBJECTIVE: To evaluate the growth of breastfed infants whose mothers had inserted an etonogestrel-releasing implant in the immediate postpartum period.

METHODS: An open, randomized controlled, and parallel trial of postpartum women who were block-randomized to early (up to 48 hours postpartum before discharge) or conventional (at 6 weeks postpartum) insertion of an etonogestrel implant. The primary outcome was average infant weight at 12 months (360 days) and a difference of equal to or greater than 10% between groups was considered clinically significant. The secondary outcomes were infant's height and head and arm circumferences. These variables were measured at baseline and at 14, 40, 90, 180, 270, and 360 days postpartum. The mixed-effects linear regression model was used to evaluate the outcomes with a power of 80% and a significance level of 1% for the primary outcome and 0.3% for secondary outcomes as a result of correction for multiple hypothesis testing.

RESULTS: From June to August 2015, a total of 100 women were randomized: 50 to early and 50 to conventional postpartum etonogestrel insertion. Sociodemographic characteristics were similar between the groups, except for educational attainment. The conventional insertion group included a higher proportion of women with 8 or more years of formal education than the early insertion group (88% [44/50] compared with 70% [35/50], P=.02). There was no difference in infant weight at 360 days between the groups (early [mean±standard deviation] 10.1±1.2 kg compared with conventional 9.8±1.3 kg, mean difference estimate 0.3 kg, 95% confidence interval 0–0.7 kg). Growth curves, height, and head and arm circumferences did not differ between the groups.

CONCLUSION: There is no difference in growth at 12 months among breastfed infants whose mothers underwent early compared with conventional postpartum insertion of the etonogestrel implant.


There is no difference in growth at 12 months among breastfed infants whose mothers underwent early compared with conventional postpartum insertion of the etonogestrel implant.

Department of Gynecology and Obstetrics, Medical School of Ribeirao Preto, University of São Paulo, São Paulo, Brazil.

Corresponding author: Carolina Sales Vieira, MD, PhD, Department of Obstetrics and Gynecology, School of Medicine of Ribeirao Preto/USP, Av Bandeirantes 3900, Campus Universitário, Ribeirao Preto, SP 14049-900, Brazil; email:

This study was cofunded by the São Paulo Research Foundation (Fundação de Amparo à Pesquisa do Estado de São Paulo-FAPESP), research grant # 2013/00795-3 and the National Council for Scientific and Technological Development (CNPq).

Financial Disclosure Dr. Braga has given ad hoc invited lectures for Merck. Drs. Ferriani and Vieira have served on Medical Advisory Boards and given ad hoc invited lectures for Merck and Bayer. The other authors did not report any potential conflicts of interest.

Each author has indicated that he or she has met the journal’s requirements for authorship.

© 2017 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.