HCG Level After Miscarriage: When Does It Come Back To Zero?

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The placenta produces the pregnancy hormone hCG (human chorionic gonadotrophin) to assist the growth of the fetus. During the first few weeks of a healthy pregnancy, it multiplies every 48 to 72 hours and can be determined through urine and blood testing (1). However, during a miscarriage, the hCG levels drop (medically referred to as a non-viable pregnancy) and may soon reach zero HCG level after a miscarriage.

Read this post to learn how long hCG levels last after a miscarriage, when they return to pre-pregnancy levels and if you can ovulate with hCG in your system after a miscarriage.

How Long Does It Take For The hCG Levels To Fall To Zero After A Miscarriage?

La Toya Luces-Sampson, MD, FACOG, a board-certified obstetrician and gynecologist from Stockton, California, says, “hCG levels usually rapidly decline after a complete miscarriage, passing all of the pregnancy tissue, but can take several days to weeks to reach zero once the levels become very low.”

The duration varies from woman to woman. It is likely to depend on how high your hCG levels were during the miscarriage. Usually, test results of fewer than five mIU/mL are considered negative or zero (1).

If you had a miscarriage early in your pregnancy, your levels are usually low, and hCG levels return to zero in less time. On the other hand, if the levels are high at the time of the miscarriage or if you had a miscarriage late in your pregnancy, it might take several days or weeks to return to zero (2).

According to the American Association for Clinical Chemistry (AACC), urine hCG and serum hCG levels may take anywhere between nine and 35 days to disappear from your system (3).

Why Do hCG Levels Keep Increasing After A Miscarriage?

The hCG level can increase after a miscarriage in the case of:

  1. Heterotropic pregnancy: Simultaneous occurrence of extra-uterine (ectopic pregnancy) and intrauterine pregnancy)
  2. Persistent trophoblastic disease: Molar tissue starts growing again after the removal of molar pregnancy

Dr. Luces-Sampson adds, “There may be a fetal demise with no passage of tissue, where the hCG levels continue to rise, stay the same, or slightly decrease over time. In this case, the diagnosis is confirmed by ultrasound.”

Molar tissues causes rise in HCG level after miscarriage

Image: Shutterstock

How Soon Can You Get Pregnant After A Miscarriage?

While some doctors may recommend waiting for three months several experts opine that there is no need to delay pregnancy after an early pregnancy loss (4).

Experts say
According to the CDC, ovulation can occur within two to three weeks after a miscarriage. So, you may need to use birth control methods if your doctor has suggested to space further attempts of conceiving to ensure complete recovery (9) (10).

Can You Get A Pregnancy False-Positive Reading After Miscarriage?

Yes, you might get a false-positive test reading after a miscarriage because hCG may still remain in your bloodstream for weeks following a pregnancy loss. Thus, the test readings might show that you are pregnant even when you are not (5).

Can You Ovulate With hCG In Your System After A Miscarriage?

You will ovulate if your hCG levels drop below 5mIU/mL

Image: Shutterstock

hCG hormone is likely to suppress your normal ovulation process. Your next cycle may start only when the hCG levels drop below 5mIU/mL (6).

Quick fact
Ovulation usually occurs earlier if there is an early pregnancy loss compared to a miscarriage at a later stage where hCG had attained higher levels (11).

Frequently Asked Questions

1. Why won’t my HCG levels go down even after a miscarriage?

It may take about four to six weeks for HCG levels to return to normal after a miscarriage, so you get a positive hCG report if tested. Moreover, some women may conceive immediately after a miscarriage, and the new pregnancy may be responsible for the presence of hCG in the blood (7).

2. How can I check my hCG levels at home?

Home pregnancy test kits detect the presence or absence of hCG levels. However, they cannot detect hCG quantitatively. Therefore, blood tests are the only way of detecting hCG levels.

3. Does hCG have to be zero to get a period?

hCG levels need to be near zero for ovulation to occur. Once ovulation occurs, you get a period after about two weeks (8).

4. Do low hCG levels mean a miscarriage?

Dr. Luces-Sampson observes, “A ‘low’ hCG should be taken with a grain of salt because one number in isolation gives very little information. Serial (usually every 48 hours) hCG tests are needed to accurately predict pregnancy loss. The hCG levels usually double every 48 hours, but the increase can be as low as a 50% increase and still indicate a normal pregnancy.”

HCG levels after miscarriage may decline in most women. However, it may give positive results for a few weeks. When the pregnancy is lost, the HCG production ceases from the placenta. Heterotopic pregnancy, which is two pregnancies with different implantation sites and gestational trophoblastic diseases, can cause increasing HCG levels in the blood after miscarriage. Lower HCG hormones are less likely to impact ovulation, so it is possible to start the next cycle when the HCG levels fall below certain levels. You may seek medical care and do HCG blood tests during follow-ups after miscarriage.

Infographic: Does HCG Level Predict Risks For Miscarriage?

HCG levels can be low or abnormally high for various reasons in viable and nonviable pregnancies. Clinical symptoms and prenatal ultrasound help to establish a better diagnosis than HCG levels alone. Go through the infographic to learn about HCG level changes and miscarriage risks in pregnancy.

hcg level changes and miscarriage risk [infographic]
Illustration: MomJunction Design Team

References:

MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
1. HCG (Urine); University of Rochester Medical Center
2. Danielle Betz and Kathleen Fane; Human Chorionic Gonadotropin (HCG); : StatPearls Publishing; (2020)
3. Pregnancy Test (hCG); American Association for Clinical Chemistry
4. Karen C. Schliep, et al.; Trying to Conceive After an Early Pregnancy Loss: An Assessment on How Long Couples Should Wait; Obstet Gynecol (2017).
5. 1st Trimester Bleeding and Pregnancy Loss; OB-GYN 101: Introductory Obstetrics & Gynecology
6. Beata E. Seeber; What serial hCG can tell you, and cannot tell you, about an early pregnancy; Fertility and Sterility; American Society for Reproductive Medicine – Elsevier Inc (2012).
7. What is HCG?; American Pregnancy Association.
8. Leading Fertility Expert’s Guide To Getting Pregnant Again After A Miscarriage; Harley Street Fertility Clinic.
9. How To Be Reasonably Certain that a Woman Is Not Pregnant; CDC
10. Pregnancy intentions and contraceptive uptake after miscarriage;NCBI
11. Getting Pregnant Again After A Miscarriage; Harley Street Fertility Clinic
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