The short version
hCG is the pregnancy hormone that blood tests (“betas”) measure. In early pregnancy it usually rises fast, then the rise slows as the number gets higher [1][2]. That’s why clinics often repeat the test about 2 days later and look at the change, not one number [1][3].
A doubling time is only part of the picture. Clinics also look at how high the numbers are and at an ultrasound [1][3]. A slower rise doesn’t always mean a problem, and a typical rise doesn’t rule one out [1][2][4]. Your clinic is the one to read your results.
What clinics look at
- The trend over 2 or 3 tests, usually about 48 hours apart [1][3].
- Results from the same lab. Different labs and test kits can give different numbers for the same blood sample, so a change between two labs can mislead. If you can, have both tests done at the same lab, and tell your clinic if they weren’t [5][6].
- How fast it rises at lower levels. A US study followed 285 women who had pain or bleeding early in pregnancy and whose pregnancies turned out to be growing normally in the uterus. Over 2 days, 99 in 100 of them rose by at least about 49% when the first result was under 1,500, about 40% from 1,500 to 3,000, and about 33% above 3,000 [2]. A rise above these numbers doesn’t confirm a healthy pregnancy, and a rise below them isn’t a diagnosis on its own [1][2][4].
- An ultrasound, to see where the pregnancy is. Very early on, a pregnancy in the uterus can be too small to see yet, so clinics read the scan together with the hCG numbers [1][4].
After IVF or a trigger shot
If you had an hCG trigger shot (such as Ovidrel, Novarel or Pregnyl), hCG from the shot stays in your blood for days and can show up on a pregnancy test. A test taken too soon can be a false positive [7][8]. For home tests, one ob-gyn advises waiting at least 2 weeks after your last hCG shot [8]. Your clinic sets the day for your first beta. Use the dates your clinic gives you.
When to get care now
Get emergency care for sudden, severe pain in your belly or pelvis, shoulder pain, or feeling weak, dizzy or faint. These can be signs of a ruptured ectopic pregnancy, which can cause life-threatening bleeding [9]. This applies whether your numbers are rising, flat or falling [1][4].
Call your clinic or provider about bleeding, cramping, or any result that worries you.
If your numbers fall
A falling result is hard news to read on a screen. Please call your clinic. They’ll explain what it means for you and what happens next. While you wait, the emergency signs above still apply. If it does turn out to be a pregnancy loss, miscarriage: what happens, your options, and support has people you can talk to.
Sources
- American College of Obstetricians and Gynecologists, Practice Bulletin No. 193, “Tubal Ectopic Pregnancy” (2018, reaffirmed 2025). acog.org
- Barnhart KT, Guo W, Cary MS, et al., “Differences in Serum Human Chorionic Gonadotropin Rise in Early Pregnancy by Race and Value at Presentation,” Obstetrics & Gynecology 2016;128(3):504–511. PubMed
- American College of Obstetricians and Gynecologists, Practice Bulletin No. 200, “Early Pregnancy Loss” (2018, reaffirmed 2025). acog.org
- Barash JH, Buchanan EM, Hillson C, “Diagnosis and Management of Ectopic Pregnancy,” American Family Physician 2014;90(1):34–40. aafp.org
- Grenache DG, “Human Chorionic Gonadotropin,” Pearls of Laboratory Medicine, Association for Diagnostics & Laboratory Medicine (2011). myadlm.org
- Imudia AN, “Comprehensive management approach for ectopic pregnancy,” Contemporary OB/GYN (2018). contemporaryobgyn.net
- US Food and Drug Administration–approved labeling, Ovidrel (choriogonadotropin alfa injection), EMD Serono, revised December 2023, via DailyMed (National Library of Medicine). dailymed.nlm.nih.gov
- Cleveland Clinic, “Causes of a False Positive Pregnancy Test” (2021). health.clevelandclinic.org
- American College of Obstetricians and Gynecologists, “Ectopic Pregnancy.” acog.org