Define effect on Oestrogens and progesterone in pregnancy?
Oestrogens and progesterone are secreted by the placenta from 8-10 weeks of gestation. Progesterone increases throughout pregnancy. It stimulates maternal respiration ensuring an adequate supply of oxygen to the foetus. In addition, it relaxes smooth muscle in the uterus to accommodate the growing foetus and allow for child birth. Progesterone, while stimulating lobular development in the breast, inhibits milk secretion during pregnancy.