[Hierdence of X-chromatin post partum].

Determinations of the X-chromatin frequency in buccal smears were performed in 33 pregnant women at the day before delivery and daily for seven days thereafter. In 23 women with a spontaneous delivery there was a statistically significant drop in the X-chromatin frequency after delivery being lowest on the second day. On the fifth day the X-chromatin frequency had reached the predelivery level. In 10 women with operative delivery by cesarean section and hormonal suppression of lactation no such changes in the X-chromatin-frequency have been noted.