If you’re feeling that this pregnancy is a little more intense than prior ones (or even just more than what your friends warned you to expect if you’ve never been pregnant before), there’s a good chance it has run through your mind that you might be pregnant with twins.
With thoughts of twins on your mind, you may have heard that higher hCG levels are linked to multiples and wonder how your counts compare. You may be wondering what hCG even is — let alone how it could be proof that someone’s having twins.
No matter what’s generated your interest in hCG levels and twins, we’ve got the answers you’re seeking. (Spoiler alert: While higher levels of hCG can indicate twin pregnancy, it is by no means definitive. You’re going to want to get an ultrasound to know for sure.)
Human chorionic gonadotropin (hCG) is a hormone produced by the body during pregnancy to support fetal growth.
The purpose of this hormone is to communicate to the pregnant body that it needs to continue to produce progesterone. This prevents menstruation and protects the uterine lining during pregnancy.
If you’re not pregnant and your hCG level is unusually high, it can be a sign of cancer, cirrhosis, ulcers, or inflammatory bowel disease (IBD). Your doctor will do follow-up exams and tests if you present with high hCG levels and you aren’t pregnant.
This table displays normal hCG levels during pregnancy.
|Weeks from last menstrual period||Normal hCG levels (mIU/mL)|
|Note: Normal hCG levels for nonpregnant women are less than 10.0 mIU/mL.|
Looking at the table, you may notice that there is a very wide range of acceptable levels for every week after your last menstrual period. You can also see that normal hCG levels increase and then eventually level off before decreasing during the course of a typical pregnancy.
Indeed, hCG levels are usually analyzed over a period of time and not just used as a one-time determinate.
A single test of hCG levels is not generally that useful because there are a variety of factors (including maternal smoking, body mass index (BMI) levels, use of fertility drugs, placental weight, the fetus’ sex, and even ethnicity) that can place someone within a wide range of acceptable hCG levels throughout their pregnancy.
The first blood test for hCG typically provides your doctor with a baseline. From there, your doctor will look to see how the hCG level changes over time in subsequent blood tests.
In the first 4 weeks of a viable pregnancy, hCG levels generally double every 48 to 72 hours. After this, the hCG levels should grow more slowly doubling approximately every 96 hours around the 6-week point.
A doctor may pay close attention to your hCG levels early in pregnancy, because failing pregnancies typically have a longer doubling time early on and may even begin to fall when they should be doubling. (Pregnancies that start with a higher baseline of hCG may take slightly longer to double without this being a sign of concern in the pregnancy.)
If your doctor notices that hCG levels are not following expected patterns, they may request additional blood draws every few days in order to get a better idea of how the levels are changing.
In a typical viable pregnancy, levels of hCG should peak around 10 to 12 weeks after your last menstrual cycle and slowly diminish throughout the rest of the pregnancy.
Within a few weeks of delivery, hCG levels should be undetectable. In the rare case this does not happen, it may indicate some remaining hCG-producing tissue exists that will need to be removed.
hCG levels that do not follow a typical pattern have been associated with adverse pregnancy outcomes. These include fetal loss, preeclampsia, preterm delivery, and chromosomal abnormalities.
If you have any concerns about your hCG levels that don’t seem “typical,” don’t hesitate to ask questions! Your healthcare provider is there to share the facts and reassure you when you’re concerned.
What low hCG levels might mean
If you’re pregnant, but are experiencing lower than expected hCG levels, it may be a sign of:
- miscarriage or blighted ovum
- ectopic pregnancy
- miscalculation of the pregnancy dates
What high hCG levels might mean
If you’re pregnant, but have higher than expected hCG levels, indeed you may be carrying multiples!
According to one 2012 report in the journal Fertility and Sterility, several studies have shown that women pregnant with multiples had higher hCG base level counts, but demonstrated similar doubling patterns to women pregnant with single babies.
Other reasons you may have a higher than expected hCG levels:
- a molar pregnancy
- miscalculation of the pregnancy dates
Store-bought pregnancy tests
You may not have put much thought into hCG if you’ve never been pregnant before or taken fertility treatments. If you ever took a store-bought pregnancy test thinking you might be pregnant, you’ve tested for hCG though.
Many of the store-bought pregnancy tests will only tell you whether they’ve detected enough hCG to determine you’re pregnant. Depending on how soon after your missed menstrual cycle you took the test and even what time of the day, you may not have had a high enough content of hCG hormone in your urine yet to register resulting in a false negative test.
A store-bought test will not reveal you exact hCG count, but a blood draw performed by your doctor can provide you with more specific hCG numbers.
While a higher hCG count may indicate twins, as noted in this
Therefore, in order to make a determination of whether or not you’re pregnant with multiples, your doctor will need to perform an ultrasound. Good news: Multiples can be detected by ultrasounds as early as 6 weeks after conception!
In addition to higher hCG levels during your pregnancy, if you’re pregnant with multiples, you may also experience:
- increased nausea
- increased fatigue
- increased weight gain (usually later in pregnancy, though you may show earlier)
- a second heartbeat on the doppler (a definite sign you’ll want to have an ultrasound to confirm how many babies you’re carrying)
If you find that you’re feeling extra, extra pregnant and believe that you might have twins on the way, there’s really no substitute for an ultrasound to confirm that you’re carrying multiple little ones.
Increased hCG levels can be an indicator of a pregnancy that includes twins, but it’s not conclusive evidence. (It could just mean that your pregnancy dates have been miscalculated.)
It’s important to talk to your doctor about any changes you’re experiencing throughout your pregnancy as well as any fears and concerns you may have.