Question

Why does testing for hCG (human chorionic gonadotropin) work as a pregnancy test early in pregnancy but not late in pregnancy? What is the function of hCG in pregnancy?

Short answer

The human chorionic gonadotropin works as a test in early pregnancy because the hCG levels in the body rise as the woman is about to become pregnant. It induces the formation of the placenta.

The function of hCG in pregnancy is to regulate the progesterone production in the corpus luteum during pregnancy.

Step-by-step solution

Human chorionic gonadotropin

hCG is a hormone produced by men and women for different reasons. hCG in females suggests pregnancy. Pregnant females start producing hCG as it helps in placental development.It is produced by the trophoblast cells that envelop the growing embryo.

In males, hCG helps in the production of sperm and testosterone. It stimulates Leydig cells in the production of testosterone. hCG is an analog for luteinizing hormone in males as it stimulates the production of sperms, thus maintaining fertility in males.

hCG in early pregnancy test

The cells in the female reproductive system that become the placenta produce the hormone hCG.In the first few weeks of pregnancy, HCG levels in the body rapidly increase; it stimulates the corpus luteum in generating progesterone that helps regulate pregnancy.

The hCG levels in a female indicate pregnancy and suggest the development of the embryo and the progress of the pregnancy.

hCG test in late pregnancy

HCG levels drop during the second trimester, the corpus luteum disintegrates, and the placenta takes over progesterone production entirely.Thus, if the pregnancy test is done during the second trimester, the hCG levels will not help in indicating positive pregnancy.

So, the presence of hCG during the first trimester suggests the positive pregnancy test, which eventually drops in the second trimester. Hence, the hCG test in late pregnancy is not effective. The function of hCG is to help the placental development of the trophoblastic cells.

Function of hCG

Human chorionic gonadotropin interacts with the ovary's LHCG (luteinizing hormone/choriogonadotropin) receptor. It promotes the corpus luteum, which enables the mother to maintain to recognize pregnancy early.

During the first trimester, hCG allows the corpus luteum to secrete the hormone progesterone.

It has been observedseen that hCG could have a role in developing local maternal immune tolerance. Endometrial cells treated with hCG, for example, cause an increase in T cell death.