Beta-HCG (Quantitative)

HCG (human chorionic gonadotropin) is a glycoprotein hormone produced by the placenta.

Shortly after implantation of a fertilised egg into the uterine wall, the trophoblast begins to produce hCG, which maintains steroid secretions from the corpus luteum until the placenta can do so.

In normal pregnancies, hCG can be detected after implantation, seven to nine days after conception (or 22 to 24 days after the last menstrual period of a normal 28-day cycle).

Concentrations of hCG double approximately every 1.5 to 3 days for the first six weeks, then continue to increase until peaking at 8-10 weeks gestation, before gradually decreasing for the remainder of the pregnancy.

After delivery, hCG returns to < 5 mIU/mL (IU/L) and is generally undetectable for several days after delivery.

The hormone is an excellent marker of pregnancy in serum, plasma or urine.

During pregnancy, abnormally low or rapidly falling levels may indicate an abnormal situation such as an ectopic pregnancy or an imminent spontaneous abortion.

Progesterone is produced mainly by the corpus luteum of the ovary in women with normal periods. Secondary sources of progesterone are the adrenal cortex in men and women, and the testes in men.

Progesterone levels are low during the follicular phase of the menstrual cycle. After ovulation, progesterone production by the corpus luteum increases rapidly, reaching peak levels 4 to 7 days after ovulation. These levels are maintained for 4 to 6 days, then fall back to baseline levels, causing menstruation.

The main functions of progesterone are to prepare the uterus for implantation and to maintain pregnancy.

In the event of implantation, the trophoblast begins to secrete hCG (human chorionic gonadotropin), which maintains the corpus luteum and its secretion of progesterone.
During pregnancy, progesterone levels increase steadily, reaching their highest level during the third trimester.
Serum progesterone is a reliable indicator of natural or induced ovulation because it rises rapidly after ovulation.

Ovulation disorders, including anovulation, are relatively common and are responsible for infertility in around 15-20% of patients. Progesterone levels are abnormally low in these patients during the mid-luteal phase.

Luteal phase deficiency is a reproductive disorder associated with infertility and spontaneous abortion and is thought to affect 10% of infertile women.