Though most pregnancy tests aren’t 99 percent accurate until after your missed period, some women get positive pregnancy tests much earlier than that. But so much can happen during early pregnancy, and sadly, not all embryos make it. A miscarriage in this very early stage of gestation is called a chemical pregnancy.
What is a Chemical Pregnancy?
A chemical pregnancy is what happens when you miscarry before the fifth week of gestation, or approximately within one week of when you would get your expected period. (source)
Women who test early may get a positive pregnancy test, because their bodies begin producing enough hCG. However, when a chemical pregnancy occurs, your body stops producing hCG shortly thereafter, levels begin to decline, and you start to bleed.
What Causes a Chemical Pregnancy?
In the case of a chemical pregnancy, an egg is fertilized and implants, but does not survive beyond those initial stages. “The fertilized egg still produces enough hCG to cause a positive result on a pregnancy test, but the implantation itself is never fully completed,” says Rebecca Lee, a New York-based registered nurse and creator of RemediesForMe.com. “The gestational sac cannot be seen on an ultrasound, because it is not large enough.”
Lee says most chemical pregnancies—like any miscarriage—are caused by chromosomal abnormalities, advanced maternal age (over the age of 35), clotting diseases, and thyroid disorders. In the vast majority of cases, there is nothing mom did—or didn’t do—to cause a chemical pregnancy.
Is a Chemical Pregnancy the Same as a Miscarriage?
Yes, a chemical pregnancy is a type of miscarriage. It is considered a very early miscarriage.
Is Chemical Pregnancy the Same as a Blighted Ovum?
No. They are both very early miscarriages, but there are some key differences:
- A chemical pregnancy usually ends before a gestational sac forms
- A chemical pregnancy occurs before week 5
How Common Are Chemical Pregnancies?
I know how nerve-wrecking those first few weeks can be—especially if you got an early positive test result. There’s so much to be excited about, but the road ahead is still long. It’s normal to feel a bit anxious, but the odds are on your side: Only about 1 percent of women will have two or more miscarriages. (source)
When it comes to chemical pregnancies, researchers say it’s hard to pinpoint a statistic, because so many women experience chemical pregnancies before they even know they’re pregnant. (They just assume that their period was a few days late.) However, some moms are aware of their chemical pregnancy because they’re trying to conceive and testing regularly and early.
“Many biochemical pregnancies are discovered today that would otherwise have gone undetected due to the ultra sensitive pregnancy tests on the market, which make it easier to get a positive result 3 or 4 days before a woman’s period is due.” (source)
In one study of 370 embryo transfers:
- 30 (or 8.1 percent) ended in chemical pregnancy,
- 4 (or 1.1 percent) ended in an ectopic pregnancy,
- 23 (or 6.2 percent) ended in a clinical miscarriage (a miscarriage that’s diagnosed after a fetal heartbeat can be heard or there’s visual evidence of a gestational sac on an ultrasound),
- and 135 (36.5 percent) resulted in ongoing pregnancies.
Chemical Pregnancy Symptoms and Signs
Most often there are no signs or symptoms to indicate a chemical pregnancy. As noted above, many women don’t know they are experiencing a chemical pregnancy unless they are testing regularly. (source)
However, some clues that you may be having a chemical miscarriage include:
- A faint positive pregnancy test that just gets lighter as days go on
- No early pregnancy symptoms like tender breasts, nausea, bloating, etc.
- Heavier cramping and bleeding than their typical menstrual flow
Note: Not all cramping and bleeding indicates a miscarriage. It could just be part of your premenstrual/menstrual cycle or you could go on to have a healthy pregnancy as some women do cramp and bleed early on.
Chemical Pregnancy hCG Levels
Chemical pregnancies occur early enough in the gestation period, that they won’t be detected on an ultrasound. But, as discussed above, your body may produce enough hCG for a high-sensitivity pregnancy test to detect it.
In a chemical pregnancy hCG levels will be < 100 mIU/mL. (source) For contrast, in a healthy singleton pregnancy, hCG levels should be between 300-600 about 4-5 weeks after your last menstrual period.
Unfortunately, when a chemical pregnancy occurs, your body will stop producing hCG and your levels will begin to decline shortly after.
Can a Chemical Pregnancy Cause a Missed Period?
A chemical pregnancy typically happens before a missed period, which means you’ll get your period as expected. (source)
When you do get your period, you can expect bleeding to be the same as your normal period or a bit heavier, says Dr. Brett Worly, assistant clinical professor of obstetrics and gynecology at The Ohio State University Wexler Medical Center. (source) But bleeding should not be so heavy that you are soaking more than two pads an hour for two hours in a row, he adds. If this happens, contact your healthcare provider right away.
In some cases a chemical pregnancy may cause a late period.
If a chemical pregnancy occurs after a missed period, it’s usually within a week. Because of this, unless you’re testing early, many women may just suspect their period is a bit late. Even if the chemical pregnancy occurs after your missed period, bleeding is typically consistent with that of a normal period, since a gestational sac never formed.
When a chemical pregnancy occurs, consider the first day of bleeding as the first day of your next cycle , says Dr.Philippa Kaye. Many women ovulate as normal following a chemical pregnancy, though some may experience a slightly longer cycle.
Treatment for a Chemical Pregnancy
While no specific treatment is typically required for a chemical pregnancy, it’s important to follow up with your healthcare provider in order to differentiate it from an ectopic pregnancy. (source) If you’ve had multiple chemical pregnancies and/or miscarriages, then your doctor may also run some tests to determine whether or not there is an underlying cause.
Once you’re in the clear, you might also consider taking some natural steps to boost your fertility, including eating a real food diet, decreasing stress, tracking your cycles, having sex at peak fertility, taking special supplements, and genetic testing.
Natural Ways to Heal After a Chemical Pregnancy
No matter what stage you are at in your pregnancy, miscarriage is a difficult process—I know firsthand. Allow yourself time to heal and time to grieve if you need it. You might also want to consider:
- journaling your feelings,
- reading for relaxation,
- and resting and/or meditating.
It’s also important to remember there’s nothing you could have done to prevent the chemical pregnancy from occurring. Lee reminds couples who are trying to conceive: “The good news is that chemical pregnancies are a good sign that your body is capable of getting pregnant and it shouldn’t be too long until you do get pregnant again.”
As long as you are given the go ahead by your healthcare provider, then it’s OK to start trying again right away. In fact, research shows it may be the best time to get pregnant. Some studies suggest TTC sooner may even lower your chances of future miscarriage. (source)
How About You?
Have you experienced early pregnancy loss or a chemical pregnancy? As hard as it may be, your story may help others going through the same thing.