Is Miscarriage Imminent If hCG Is Not Doubling?

Find Out What the Results of This Prenatal Exam Really Mean

pregnant woman getting blood drawn
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There is a lot to think about over the course of a pregnancy. For most pregnant women, the journey begins with increased levels of human chorionic gonadotropin (hCG), the hormone that most at-home, urine-based pregnancy tests detect.

After a pregnancy is confirmed, those levels of hCG continue to increase. Most women are aware that their hCG level should begin to increase quickly, even double over the course of early pregnancy.

But many women wonder what it means if their hCG level is increasing but not doubling in early pregnancy. Is this a sign of miscarriage?

hCG Levels and Miscarriage

The short, and perhaps frustrating, answer is maybe, but maybe not.

Human chorionic gonadotropin (hCG) is a hormone that you create when you're pregnant in the cells of your placenta, and its presence in your body is the reason that your at-home, urine-based pregnancy test, as well as your in-office, blood-based pregnancy test were positive.

Doctors tend to monitor your hCG level throughout your early pregnancy because it's one marker that tells your physician how your pregnancy is progressing. Blood tests that check for hCG can be either qualitative (and simply tell you whether hCG is in your blood or not) or quantitative (and tell you exactly how much hCG is in your blood).

In about 85% of normal pregnancies, the level of the hormone hCG will double every two to three days during early pregnancy—usually throughout the first four weeks.

 When the hCG level is increasing but not doubling at least every 3 days, this may be a warning sign of an impending miscarriage—but not necessarily. 

hCG Patterns in Early Pregnancy

For instance, in one study that monitored hCG increase patterns in early pregnancy, the lowest documented 2-day hCG increase in a normal pregnancy was 53%.

This means that an hCG level that increased by about 75% (rather than by 100%) after three days could, theoretically, still be normal. In other words, if your hCG levels aren't exactly doubling, but are still increasing by a significant amount, then you may still have a healthy pregnancy.

If your hCG levels are increasing but not doubling in early pregnancy, your doctor will likely monitor your pregnancy more closely. For example, your physician might ask you to come in for more frequent blood tests to keep checking your hCG level. 

Remember, too, that the rate of hCG doubling slows down as your pregnancy progresses, so slower hCG doubling times are normal if you're past the first four weeks or so of pregnancy. As your pregnancy goes on and your hCG level passes roughly 1,200 mIU/ml, it tends to take longer to double. By week six or week seven, for instance—about halfway through your first trimester—it may take about three and a half days to double.

hCG Levels in the Second Half of the First Trimester

After you hit an hCG level of 6,000 mIU/ml, it may be four days or more until it doubles.

Your hCG level tends to peak between week eight and week 11 of gestation. But keep in mind, these are estimates—the exact timeframe is different for every woman. By the second half of the first trimester, ultrasound is more reliable than hCG levels for judging whether a pregnancy is viable.

But When Your hCG Level Is Actually Decreasing

One important caveat: If your hCG level not only isn't doubling but is actually decreasing in early pregnancy, that is, unfortunately, a reliable sign of miscarriage. 

If your hCG level isn't doubling or is decreasing, make sure that you're aware of the symptoms of miscarriage just in case. Call your doctor immediately if you notice any vaginal bleeding, cramping, or the passing of any tissue through the vagina.

A miscarriage can be extremely difficult to handle, both physically and emotionally, so if you do experience one, give yourself an appropriate amount of time to recover and grieve. Your doctor can likely direct you toward support groups that can help you cope. 


Barnhart, Kurt T. MD, MSCE; Sammel, Mary D. ScD; Rinaudo, Paolo F. MD, PhD; Zhou, Lan PhD; Hummel, Amy C. CCRC; Guo, Wensheng PhD. "Symptomatic Patients With an Early Viable Intrauterine Pregnancy: hCG Curves Redefined." Obstetrics & Gynecology: July 2004 - Volume 104 - Issue 1 - pp 50-55.

Human Chorionic Gonadotropin (hCG) - The Pregnancy Hormone. American Pregnancy Association. Accessed: Apr 5, 2010.

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