To determine the levels of hCG in your body, you’ll need a blood test from your doctor. HCG levels usually double every 29-53 hours during the first few weeks of pregnancy, according to Dr. Brennan Lang, an Ob-Gyn at Baylor Obstetrics and Gynecology at Texas Children’s Pavilion for Women. The levels eventually peak around 8-10 weeks after implantation, and they plateau as the pregnancy progresses.
Dr. Lang says hCG usually reaches 90-100,000 mIU/mL. But when analyzing hCG test results, doctors pay attention to trends instead of numbers. That’s because there’s a wide range of normal hCG levels, and as long as hCG rises as expected, the pregnancy is probably healthy.
Decreasing or plateauing hCG levels in early pregnancy could signal miscarriage, blighted ovum, or ectopic pregnancy. On the other hand, unusually high hCG levels could indicate molar pregnancy, placental tumor, or pregnancy with multiples. Note that unexpected hCG levels could also indicate that you’re further along in your – or not as far along – as expected.
Sometimes with multiples, there is a higher initial hCG trend increase, says Maureen Baldwin, M.D., MPH, an assistant professor of Obstetrics and Gynecology at Oregon Health and Science University. Specifically, twin and multiple pregnancies might have 30-50% higher hCG levels than singleton pregnancies.
Even so, a detection of high hCG levels can’t reliably predict twin pregnancies. That’s because hCG levels vary greatly between each woman, and there’s a wide range of normal levels. Plus, not every woman has increased hCG numbers with twins, triplets, or other multiples.
“While your hCG level may be higher than expected or rise faster, we cannot reliably predict whether or not you will have twins until we see them on ultrasound,” says Dr. Lang. This ultrasound happens around the sixth week of pregnancy. Dr. Lang also adds that “sometimes an unrecognized vanishing twin can affect the rise or fall of hCG levels in early pregnancy and confuse the picture of an otherwise normal pregnancy.”
As long as your hCG levels continue to rise, higher-than-normal numbers shouldn’t affect the health of your pregnancy. Your doctor will monitor your levels to rule out health problems like molar pregnancy and placental tumors. And who knows– your six-week ultrasound might show you’re carrying multiples after all!