Levonorgestrel used for emergency contraception during lactation-a prospective observational cohort study on maternal and infant safety.

Objective: To identify possible effects of levonorgestrel used as an emergency contraceptive during breastfeeding on mothers and their infants.
Study Design: A prospective observational cohort study of all women who contacted the Teratology Information Service between January, 2005 and January, 2010. Breastfeeding women who used levonorgestrel as an emergency contraceptive (study group) were compared to breastfeeding women who used either ethynodiol diacetate or desogestrel (control group). Women were followed for 6-24 months. Main outcome measures were adverse maternal and infant effects and continuation of breastfeeding.
Results: We followed 71 of 128 study group women and 72 of 100 control group women. Maternal adverse effects were mainly vaginal bleeding, which was less frequent in the study vs. control group (16 of 71 vs. 27 of 72, p = 0.068). Decreased lactation was uncommon and similar in both groups. Breastfeeding was reinitiated within less than 8 h in 75% of the levonorgestrel group women. Adverse infant effects were rare (0 of 72 infants vs. 2 of 72 infants, p = 0.5 in the study vs. control group).
Conclusions: Our findings support the safety of using levonorgestrel as an emergency contraceptive during lactation without the need for withholding breastfeeding.