hCG Levels in Early Pregnancy

hCG is short for the “human chorionic gonadotropin” hormone. This is the hormone that pregnancy tests look for when determining whether or not the tester is pregnant, typically 8-14 days after conception. It is found in your urine and blood, and its levels are a vital tool for health care professionals while searching for abnormalities in the fetus after pregnancy has been established. In 85% of pregnancies, hCG levels double every 72 hours before peaking between the 8^th and 11^th weeks of pregnancy. After peaking, the levels begin to decline between the 12^th and 16^th weeks of pregnancy, then level off until after childbirth.

After conception, your body begins producing various hormones to ensure your developing baby receives all necessary nutrients and oxygen. hCG is made by cells that form the placenta. There are two types of hCG tests: qualitative hCG tests (detect presence of the hormone) and quantitative hCG tests (measures the amount of hCG present in blood). Quantitative hCG tests may also be referred to as beta hCG tests.

What do hCG Levels Mean?

The most important thing to remember when examining hCG levels is that every pregnancy and woman is different. What is normal for one woman does not necessarily mean it is normal for another woman. Some women have low hCG levels throughout their pregnancy and have healthy babies and vice-versa. The hormone is produced throughout your pregnancy. hCG maintains the corpus luteum, which is responsible for progesterone production during the early stages of pregnancy. Progesterone’s major job is to maintain the thickness of the uterine lining. A thick lining increases the chances of a healthy pregnancy. If there is no hCG present in your body, the lining will begin to shed and you will begin your period shortly after.

The hCG hormone is measured in milli-international units per milliliter, or mIU/ml. Typically, when you are not pregnant, your levels are less than 5 mIU/ml. When you are pregnant, your hCG levels will be 25 mIU/ml or higher. If levels are higher than expected based on how far along you are, it may indicate a multiple gestation, molar pregnancy or a miscalculation of the pregnancy date. A number of things can cause low hCG levels ranging from a miscalculation of the pregnancy date to a possible miscarriage, ectopic pregnancy or blighted ovum. Many times, one reading is not enough. Second or third readings, especially taken days apart, can yield more accurate results.

As stated, hCG levels are used initially to determine pregnancy, but that is not all. They are also used to determine other things such as abnormalities in the fetus. During a prenatal visit, your doctor may want to give you a Triple Screen Blood test. This test measures the alpha fetoprotein levels, as well as the hCG and estriol (a form of estrogen) levels to evaluate the risk that your baby will have Down syndrome or a spinal or brain abnormality. Also, hCG levels are taken if a miscarriage is suspected in order to verify.

Fertility drugs that contain hCG may affect your hCG levels. You and your health care provider should discuss this topic if you are currently taking fertility medication. Other medications such as antibiotics or oral contraceptives do not affect your levels.

hCG Levels: Pregnancy Guideline

The following lists are guidelines for single pregnancies. Please use these numbers only as a guideline since every woman has different hCG levels. The LMP stands for last menstrual period.

• If you are not pregnant, your hCG levels should be around 5 mUI/ml
• If you are postmenopausal, your hCG levels should be around 9.5 mUI/ml

Additional facts about hCG levels include:

• Between 1,200 and 6,000 mIU/ml, hCG typically takes 72-96 hours to double. Above 6,000 mUI/ml, hCG typically takes four or more days to double
• Later in pregnancy, hCG levels mean little to how well the pregnancy is doing
• hCG levels should not be used to date pregnancies since the numbers vary so widely from woman to woman
• Single hCG level tests are typically not enough for an accurate diagnosis
• A transvaginal ultrasound should be able to show a gestational sac if the hCG levels have reached 1,000 to 2,000 mUI/ml. Ultrasound findings lower than 2,000 mUI/ml should not be used to determine the date of conception because levels can differ greatly
• Urine hCG levels are typically lower than blood levels

hCG Levels and Gender

In a study conducted by Yaron Y. et al in Human Reproduction, 1,325 pregnant women with one fetus at 10-13 weeks were tested to compare hCG levels between women carrying a female fetus and women carrying a male fetus. The findings were conclusive: women who had a female fetus had significantly higher hCG levels than women carrying males. This study takes hCG level testing to a new level when trying to time a pregnancy test. Is it possible a woman carrying a male fetus would have lower hCG levels resulting in a delayed positive urine pregnancy test? This could be a valid reason.