functions of progesterone during pregnancy
If a pregnancy occurs, progesterone is produced in the placenta and levels remain elevated throughout the pregnancy. The combination of high estrogen and progesterone levels suppress further ovulation during pregnancy. Progesterone also encourages the growth of milk-producing glands in the breast during pregnancy., causing it to thicken during the pre-ovulatory phase of the cycle. The Role of Progesterone in Women. One of progesterone's most important functions is to cause the endometrium to secrete special proteins during the second half of the menstrual cycle, preparing it to receive and nourish an implanted fertilized egg.