What Is the Relationship between Estrogen and Pregnancy?

During pregnancy, a female's body changes. These changes occur because of hormones such as estrogen. Every aspect from the development of the baby's lungs to maintaining the pregnancy in general relies on the production of estrogen and other hormones, thus there is a strong relationship between estrogen and pregnancy.

Prior to pregnancy, a woman must ovulate in order to produce a healthy egg so that fertilization can occur. The releasing of a healthy egg triggers the woman's body to produce estrogen. The heightened level of estrogen notifies the pituitary gland and the hypothalamus of the release of the mature egg. After fertilization occurs and pregnancy officially begins, the woman's hormone levels change tremendously.

The hormone estrogen is necessary to maintain the pregnancy. Estrogen's biggest responsibility during pregnancy is to control the regulation of the production of another vital pregnancy hormone known as progesterone. The placenta, which produces estrogen, begins developing as soon as implantation occurs. This means that estrogen plays an important role in the pregnancy at this point.

Hormone levels change drastically throughout a pregnancy and are not the same for every pregnancy. An obstetrician will monitoring hormone levels throughout a pregnancy. He or she will be able to tell whether the hormones are changing at a normal rate.

While fetal development, such as the growth of kidneys and reproductive organs is occurring, estrogen is working hard to ensure that these organs grow properly. Proper placenta growth is also dependent upon the production of estrogen. This hormone is also responsible for making sure that ovulation does not occur during pregnancy. In other words, estrogen is responsible for the cessation of a female's menstrual cycle during pregnancy.

Estrogen is the hormone responsible for the uterus growing nearly 20 times its non-pregnant size and for the thickening of the uterine walls. This hormone is accountable for the increased lymphatic and blood supply to the uterus. Estrogen regulates the fetus' bone density. The increased breast size that women experience during pregnancy is caused by this hormone, as well.

Even the lactation process can't occur without the correct amount of estrogen. Estrogen and pregnancy cause the breasts to swell and the areolas to increase in size. In addition, estrogen and pregnancy cause the ducts to increase in size and even the number of milk ducts to increase.

Overall, the relationship between estrogen and pregnancy can differ from woman to woman. Typically, estrogen levels in the first trimester are lower than 38 nanograms per milliliter of blood. Estrogen levels usually drastically increase by the third trimester, when they can be as high as 460 nanograms per milliliter of blood. These levels can be higher or lower, depending on the woman and factors such as age.