Elevated levels of the male hormone testosterone during pregnancy may explain why some women have difficulty breast-feeding, say Norwegian researchers.
They said their study of 180 women showed a clear relationship between higher levels of testosterone during pregnancy and low rates of breast-feeding at three and six months, BBC News reported.
The researchers said testosterone may have a negative impact on the development of glandular tissue in the breast, which would affect a mother's ability to breast-feed.
The study appears in the journal Acta Obstetricia and Gynecologica Scandinavica.