If you’ve ever felt the thrill of getting a positive pregnancy test result only to have your period arrive days later, you’re likely among the countless women who’ve had their pregnancy hopes dashed by a chemical pregnancy.
A chemical pregnancy is one that ends before the five-week mark, prior to your doctor seeing the gestational sac on an ultrasound (1). The term “chemical” refers to the way the pregnancy is diagnosed — by chemical means instead of an ultrasound. You’ll also hear it called a biochemical pregnancy.
Here, we answer your most pressing questions — and dispel misinformation — about a chemical pregnancy.
The short answer is you won’t — unless you’ve taken a pregnancy test before your period is due. The advent of highly sensitive pregnancy tests means more women are detecting chemical pregnancies by testing before a missed period (1). And although those double lines might give you a burst of hope, unfortunately a chemical pregnancy won’t progress.
Doctors call these early pregnancies a chemical pregnancy because the level of pregnancy hormone, human chorionic gonadotropin (hCG), is high enough initially to produce a positive result on a pregnancy test, but the pregnancy isn’t confirmed on an ultrasound. Attempting to arrive at a definition for chemical pregnancy, the authors of a paper in the American Journal of Epidemiology suggested it requires three factors: a low peak in hCG (< 100 mIU/mL), a rapid drop in hCG, and not much of a delay before your period arrives (2).
Taking a pregnancy test in the days after a chemical pregnancy can still show a positive result because today’s tests detect very low levels of hCG. Even though you’ve had a chemical pregnancy, some hCG remains in your body; it takes time for the pregnancy hormone to dissipate.
This chart used by doctors to time the decline of hCG following a non-viable pregnancy shows that pregnancy hormone levels may drop as little as 12% after two days and 26% after four days (3). Among women whose hCG levels started out higher (2500 MIU/mL), doctors expect to see a sharper plunge: a 32% decline after two days and 62% drop after four days.
While you may have noticed stories in your feed equating a chemical pregnancy to a false positive, that’s inaccurate. As scientists with the United Kingdom’s National Health Services Foundation Trust recently noted in a paper, “The truth is that a biochemical pregnancy was indeed a conception and is actually a very early miscarriage” (1).
Miscarriage is the most common type of pregnancy loss, with research estimating that anywhere from 10% to 25% of all clinically recognized pregnancies will end in miscarriage, per the American Pregnancy Association.(4) Chemical pregnancies may account for up to 75% of all pregnancy losses (4).
While the precise reason is unknown, researchers have theorized that problematic embryos may be somewhat to blame. A study published in Human Reproduction of women undergoing IVF found they had fewer chemical pregnancies than women with unassisted pregnancies. The authors suggested the ability to choose healthier embryos was linked somehow to fewer chemical pregnancies (5).
Your risk of a chemical pregnancy rises if you’re age 35 or older (6). Medical conditions, such blood clotting and thyroid disorders, are also thought to play a role.
A chemical pregnancy doesn’t prevent you from conceiving again soon. And although you’ll want to feel all your feels after your loss, there’s no medical reason to stop you from trying again when you’re ready. According to the American College of Obstetricians and Gynecologists, it’s possible to ovulate and become pregnant again as soon as two weeks after an early pregnancy loss (7). In fact, you may have better odds of conceiving and having a baby.
When researchers followed 2,245 women undergoing IVF, they found those with a past chemical pregnancy had a better chance at a subsequent pregnancy and live birth. The women who’d had a chemical pregnancy in their first IVF cycle enjoyed a 34% success rate with a subsequent pregnancy, compared to a 21% success rate among women without an initial chemical pregnancy (8).
However, if you’re having repeated chemical pregnancies, you’ll definitely want to consult with your doctor.