What are the roles of oestrogen and progesterone in pregnancy?

Oestrogen and progesterone are crucial hormones for maintaining pregnancy, promoting foetal development and preparing the body for childbirth.

Oestrogen and progesterone are produced by the ovaries and placenta during pregnancy. They play vital roles in maintaining the pregnancy and preparing the body for childbirth. Oestrogen is primarily responsible for promoting the growth and development of the foetus. It stimulates the growth of the uterus to accommodate the growing foetus and enhances the blood supply to the uterus by increasing the size and number of blood vessels. Oestrogen also stimulates the development of the mammary glands in preparation for breastfeeding.

Progesterone, on the other hand, is often referred to as the 'pregnancy hormone'. It plays a crucial role in maintaining the pregnancy. Progesterone helps to thicken the lining of the uterus, providing a supportive environment for the implanted embryo. It also suppresses the mother's immune system to prevent it from rejecting the foetus as a foreign body. Progesterone relaxes the muscles of the uterus, preventing premature contractions that could lead to a miscarriage or preterm birth. In addition, it prepares the breasts for milk production.

Both oestrogen and progesterone work together to maintain a healthy pregnancy. They regulate each other's levels to ensure that the pregnancy progresses smoothly. For instance, the rise in progesterone levels inhibits the release of more oestrogen, preventing overstimulation of the uterus. Conversely, a drop in progesterone levels triggers an increase in oestrogen, stimulating the uterus to contract and initiate labour.

In summary, oestrogen and progesterone are essential for a successful pregnancy. They ensure the healthy development of the foetus, prepare the mother's body for childbirth, and regulate each other to maintain a balance that supports the progression of the pregnancy.