This study aims to assess whether there is change in the growth and development of newborns whose mothers will have a etonogestrel (ENG) releasing implant inserted in the first 24 to 48 hours of delivery compared with those with standard implant insertion (6 week postpartum).

Inclusion Criteria:

• Women who desire to use the ENG implant as a contraceptive method and desire to breastfeed her newborn for ate least 3 months;
• With no contraindication to breastfeeding, whose newborn is healthy, without malformations, born at term (gestational age ≥ 37 weeks), with appropriate weight for gestational age and with normal sucking ability

Exclusion Criteria:

• Tobacco smokers, drug addicts or alcoholics;
• Women with educational levels lower than 5 years;
• Women with clinical conditions considered category 3 and 4 for implant use by the WHO;
• Women with histories of psychiatric illness;
• Women using medications that could alter the concentration of ENG,
• Women with known allergies to the local anesthetic lidocaine (used to place the implant);
• Women who wanted to keep their cyclic menstrual bleeding