Is Miscarriage Imminent If hCG Is Not Doubling?

Most pregnancy journeys begin with a positive urine test. Pregnancy tests detect a telltale sign of pregnancy: rising levels of human chorionic gonadotropin (hCG) which is produced by the placenta. During the start of a normal pregnancy, the levels of hCG increase rapidly—doubling every 2 to 3 days in the first 4 weeks.

Seeing those numbers rise can be comforting, but what if your hCG level isn't doubling? Many pregnant women worry that this is a sign of an impending miscarriage however, hCG doesn't tell the whole story.

Instead of hCG levels, an ultrasound is a more accurate indicator of a healthy pregnancy once you reach the 5 to 6-week mark.

Measuring hCG Levels

Urine tests detect the presence of hCG but not the amount. Blood tests can be either qualitative (meaning they determine if hCG is in your blood) or quantitative (determining exactly how much hCG is in your blood).

Your doctor may want to check your hCG level in early pregnancy if you experience symptoms of a miscarriage, such as bleeding and cramping. Slow-rising hCG levels can also be a sign of an ectopic pregnancy. If your hCG level is high enough (at least 2000 mIU/ml) ultrasounds can be used to detect a gestational sac and monitor fetal development.

Patterns of hCG in Early Pregnancy

Everyone is different, and hCG levels can fluctuate without indicating a larger issue. For instance, a study that monitored hCG patterns in healthy pregnancies found that the lowest documented 2-day hCG increase was just 53%.

This means an hCG level increase of about 75% (rather than by 100%, which is doubling) after 3 days could still be normal. If your hCG levels aren't exactly doubling but are still increasing, that's a good sign.

Because of these natural variations, hCG patterns alone cannot determine whether or not your pregnancy is viable. Hormone testing should always be followed up by an ultrasound before a diagnosis is made.

In the early weeks of pregnancy, hCG levels which decrease, rather than those which increase at a slower rate, are more likely to indicate a miscarriage.

The hCG level tends to peak between weeks 8 and 11 of gestation. Once you enter the second trimester, hCG will level off and decline closer to the level it was back when you were just 6 to 8 weeks pregnant.

A Word From Verywell

Although it's tempting to read into every detail during the first few weeks of pregnancy, it's best to try and be patient for your first ultrasound appointment. Increases in hCG are expected for a viable pregnancy, but this information must be viewed within the context of additional tests, signs, and symptoms. Your doctor can help you decide which tests are best for you based on your individual medical history and concerns.

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  2. American Pregnancy Association. What is HCG?. Updated April 25, 2017.

  3. Seeber BE. What serial hCG can tell you, and cannot tell you, about an early pregnancy. Fertil Steril. 2012;98(5):1074-7. doi:10.1016/j.fertnstert.2012.09.014