Effects of levonorgestrel implant upon TSH and LH levels in male infants during lactation

Abstract

Objectives: The objective of the study is to evaluate the effects of levonorgestrel transferred through breast milk on thyroid stimulating hormone (TSH) and luteinizing hormone (LH) levels in full breast-fed infants. Methods: Forty healthy postpartum women and their male newborns were recruited for the study. Women were randomly allocated to two study groups: Group 1, IUD users and group 2, Norplant ® users. Blood and milk samples were collected on the day of IUD or Norplant ® insertion and 3 and 6 months later for TSH and levonorgestrel measurements. Results: The results disclosed a significant decrease in TSH levels, and a negative relationship between LNG levels and TSH concentration in breast feeding infants at 3 months after implant insertion. The lowest TSH levels were observed at 6 months in the women from group 2. Conclusions: The overall data indicate that the LNG levels transferred to fully breast-fed infants through breast milk from Norplant ® users significantly modified their TSH levels.