During pregnancy, several hormones work in symphony to support the growing fetus and the complex body changes needed to support it. They are also important for labor and birth to occur and for the production of breast milk. Human chorionic gonadotropin, or hCG, is also known as the pregnancy hormone because it is only produced during pregnancy. According to The American Pregnancy Organization, the hCG levels typically double every 48 to 72 hours, peaking at around weeks eight to 11 of pregnancy. Human chorionic gonadotropin is required for a successful pregnancy, orchestrates the production of other hormones and is responsible for some of the side effects of pregnancy.
Pregnancy Marker
The American Pregnancy Organization explains that this hormone is also the marker used for home and lab pregnancy tests, with levels of hCG above 25 milli-international units per milliliter, or mIU/ml, considered to be positive for pregnancy. Though the fertilized egg, also called a zygote, produces hCG almost immediately after fertilization, levels are detectable in the blood around 11 days after implantation in the uterus.
Conception
Small amounts of the hCG are produced by the newly fertilized egg even before conception and implantation into the wall of the uterus. This signals the corpus luteum, or empty egg follicle in the ovary, to continue producing the hormone progesterone that keeps the lining of the uterus, called the endometrium, from shedding. Once the fertilized egg reaches the uterus, it is then able to implant for a successful pregnancy. After the placenta forms, it continues producing hCG.
Pregnancy Symptoms
As hormone levels change in early pregnancy, unpleasant symptoms such as morning sickness can occur. According to Merck.com, the hCG hormone is thought to be responsible for characteristic side effects such as nausea, vomiting and chronic and severe fatigue in the first trimester of pregnancy.
Infertility
Lower than normal levels of hCG can cause bleeding, cramping, a miscarriage or the inability to conceive. HCG is needed to signal the production of progesterone to maintain the lining of the womb and prevent it from shedding. The University of Maryland Medical Center lists hCG as a gonadotropin medication for infertility. These infertility drugs are made from natural compounds extracted from urine or genetically engineered synthetic compounds. Human chorionic gonadotropins are administered by injections instead of orally as they would break down in the digestive tract.
