How Estrogen and Progesterone Change During Pregnancy

Women who have given birth know that estrogen levels during pregnancy are hundreds or thousands of times higher than normal, which is also a normal phenomenon. So how do estrogen and progesterone change during pregnancy? This is what pregnant women want to know. If you also want to know the answer to this question, please continue reading. You will understand it completely. I hope every pregnant mother will pay attention to it at all times.

During late pregnancy, estrogen levels rise astronomically, up to 1,000 times higher than normal. The placenta contains a special type of cell called syncytiotrophoblast. It has completely replaced the ovaries' function of secreting estrogen by the 12th week of pregnancy. The adrenal glands of both the mother and the fetus secrete a precursor hormone (DHEAS), which is converted by the placenta into various forms of estrogen. At the end of pregnancy, 90% of the estrogen synthesized by the placenta is dependent on the fetal adrenal glands.

Increased estrogen is important for fetal development and can cause the physical changes mentioned earlier, such as enlarged breasts, enlarged uterus, water retention, expanded blood volume, and even mood changes.

Progesterone levels also increase during pregnancy, with peak levels reaching 6 to 8 times higher than normal. At the beginning of pregnancy, the placenta has replaced the ovaries as the main secretor of progesterone.

The placenta converts maternal low-density lipoprotein cholesterol (LDL-cholesterol) into progesterone, which is also accomplished in the specialized syncytiotrophoblast. Removal of the corpus luteum or even both ovaries after 7 weeks of pregnancy will not affect the production of progesterone.

The progesterone secreted by the ovaries is mainly to specialize the inner layer of the uterus, that is, to form the endometrium, in order to receive the fertilized egg for implantation. After this, this specialized inner membrane is called decidua. The process of fertilized egg implantation is a process of allogeneic transplantation, and how the decidua allows this foreign substance to continue to survive remains a major unsolved mystery in nature. Progesterone secreted by the placenta then promotes water retention to expand blood volume, enlarge the breasts, and prepare for lactation. In addition, it will also change the physiological state of organs such as the lungs, intestines and urinary tract.

Since the synthesis of progesterone mainly depends on the precursors provided by the mother (estrogen mainly uses the fetal adrenaline as a precursor, and the two hormones are different in this respect), the detection of progesterone levels cannot be used as an indicator to check the health of the fetus. For example, fetal death causes a sharp drop in estrogen levels in the mother's blood, but has little effect on progesterone. Some infertile women do suffer from a luteal phase defect, which refers to the inadequacy and imbalance of the amount and timing of progesterone produced by the ovaries after ovulation. They are best treated with the ovulation-stimulating drug clomiphene, but they can also receive progesterone suppositories or injections.

This progesterone supplementation should be started from the time of a positive pregnancy test result. However, studies in humans suggest that progesterone replacement therapy is unnecessary within one week of conception, while other experts suggest that it should be started after the 15th week. Currently, only animal experiments have shown that the production of progesterone still depends on the corpus luteum until the eighth week of pregnancy.

Regardless, some researchers now believe that abnormal progesterone levels early in pregnancy may indicate miscarriage or ectopic pregnancy. So if early testing shows that your progesterone levels are too low, your doctor may recommend progesterone replacement therapy, especially if you are undergoing in vitro fertilization (IVF) or have experienced recurrent miscarriages. Low progesterone levels may also indicate a problem with the early placenta's ability to convert cholesterol. Furthermore, low progesterone levels are more likely to be a result of placental abnormalities than to cause them.

How do estrogen and progesterone change during pregnancy? I believe that you already know the answer to this question after reading the above article. Although this is a more professional question, it is beneficial for everyone to know more about this knowledge. Finally, one thing we need to remind everyone is that women need to undergo regular prenatal check-ups after they become pregnant, including hormone level tests.