Human Chorionic Gonadotropin (hCG) and Pregnancy

Generally, pregnancy tests check a woman’s urine or blood for human chorionic gonadotropin (hCG) levels. The presence of hCG hormone is the earliest sign that you are pregnant. Produced during the early phase of pregnancy, this hormone is secreted by the developing embryo immediately after conception and later on by the cells from the syncytiotrophoblast (the one that forms the outermost fetal component of the placenta).

What are the roles of hCG?

One of the major functions of hCG is to sustain the production of progesterone by the corpus luteum. Other roles include maintaining the endometrium for the first trimester, stimulating the development of the placenta and secretion of estrogen, and stimulating the development of fetal gonad and synthesis of androgen by the fetal testes.

What are the guidelines to hCG levels?

Here are the hCG levels in weeks from last menstrual period (LMP): 5-50 mIU/ml (3 weeks), 5-426 mIU/ml (4 weeks), 18-7,340 mIU/ml (5 weeks), 1,080-56,500 mIU/ml (6 weeks), 7,650-229,000 mIU/ml (7-8 weeks), 25,700-288,000 mIU/ml (9-12 weeks), 13,300-254,000 mIU/ml (13-16 weeks), 4,060-165,400 mIU/ml (17- 24 weeks), and 3,640 – 117,000 mIU/ml (25-40 weeks).

The hCG level for non-pregnant females is <5.0 mIU/ml, whereas the level for postmenopausal women is <9.5 mIU/ml. These numbers are only a "guideline". What matters is not so much the hCG level, but the change in the level.

What does a low hCG level reveal?

So what happens if your hCG level is lower than normal? This can mean a number of things. A low level could indicate ectopic pregnancy, blighted ovum or possible miscarriage, or miscalculation of pregnancy dating. In case you have a low hCG level, your doctor will recheck you within 48 to 72 hours to see the changes in hCG level.

What does a high hCG level reveal?

If your hCG level is higher than normal, this could indicate multiple pregnancy, molar pregnancy, or miscalculation of pregnancy dating. In case you have a higher-than-normal hCG level, your doctor will recheck you within 48 to 72 hours to see how the hCG levels change.

What can interfere with hCG levels?

Nothing should affect your hCG level except some medications that have hCG. These drugs are commonly used in fertility treatments. Your doctor should inform you on how these medications may affect your pregnancy test. All other drugs like contraception pills, pain relievers, antibiotics, or hormone medications should not affect on tests that measure hCG.