Human chorionic gonadotropin (HCG) is a glycoprotein hormone produced by the placenta's trophoblastic cells. It plays a crucial role in pregnancy maintenance and monitoring embryo growth. Understanding HCG levels is essential for women planning a pregnancy or in early gestation to ensure maternal and fetal well-being.

What is HCG?

HCG is composed of two subunits: alpha (α) and beta (β).

▸ α-subunit: Related to other pituitary hormones (FSH, LH, TSH), which may cause cross-reactions in assays.

▸ β-subunit: Unique to HCG and responsible for its specific pregnancy functions.

In early pregnancy, HCG is secreted by syncytiotrophoblast cells into the maternal bloodstream and eventually excreted in urine. Measuring HCG helps confirm pregnancy, monitor embryo development, and assess pregnancy health.

Normal HCG Levels

In Non-Pregnant Women

▸ Blood HCG: 0–5 mIU/mL (some assays: 0–10 mIU/mL)

▸ Negative values ​​indicate no pregnancy.

Early Pregnancy (First Weeks)

▸ HCG secretion begins ~6 days post-fertilization, detectable by 8–10 days.

▸ At 4 weeks, normal HCG: 500–10,000 mIU/mL.

▸ First trimester: HCG doubles every 1.7–2 days, peaking at 8–10 weeks.

▸ After 12 weeks, levels gradually decline and stabilize.

Note: Abnormal HCG rise may indicate miscarriage or other complications. Medical consultation is advised.

Clinical Significance of HCG

▸ Confirm Pregnancy: Blood or urine HCG can detect pregnancy as early as a missed period.

▸ Monitor Early Pregnancy: Track embryo growth and viability.

▸ Detect Complications: Abnormal HCG may indicate miscarriage, ectopic pregnancy, or other reproductive issues.

▸ Support Prenatal Care: Balanced nutrition, rest, and regular check-ups help maintain healthy HCG levels.