Relationships between milk levels of hormones and growth or puberty of offspring in mice.

Milk levels of prolactin, growth hormone (GH) or progesterone on days 12-13 of lactation and their relationships with the growth or the puberty of offspring were examined in primiparous SHN mice. Milk prolactin level had negative correlations with the body weights on days 12 and 20, the growth rate between days 0 and 20 or the age and the body weight at vaginal opening of offspring. There was a significant correlation between milk GH level and the growth rate between days 0 and 12 of offspring. A positive correlation was also found between milk progesterone level and the age at vaginal opening. These results suggest that hormones in milk would have effects on the growth or the puberty of offspring.