Conceiving Twins While Taking Clomid

For every 20 pregnancies conceived with Clomid, only one will result in twins. Clomid (clomiphene), a pill taken by mouth to induce ovulation, causes twin pregnancies between 5% and 12% of the time. That's fewer than one in 10 pregnancies. Your odds of conceiving triplets (or more) on Clomid is even lower: less than 1% (less than one in 100 pregnancies).

Fertility drugs have a reputation for causing multiple pregnancies—meaning more than one child is conceived at one time, resulting in twins, triplets, or even more babies.

If you're taking Clomid, you may be nervous (or excited) about the prospect of having two or more babies at once. However, those newsworthy high-order multiple stories are more likely with injectable fertility drugs that are used during intrauterine insemination (IUI) or in-vitro fertilization (IVF) treatments.

chances of twins with clomid
Verywell / Alexandra Gordon

Why Clomid May Increase the Chance of Multiples

The ovaries contain hundreds of thousands of follicles and each follicle contains immature egg cells. Once every month, several follicles begin a process of development.

Usually, only one follicle fully develops and releases an egg. This is because once a follicle becomes mature enough on its own, the follicle releases hormones into the bloodstream that signal the body to slow down the production of egg-stimulating hormones.

Clomid works by tricking the body into bumping up egg-stimulating hormones, causing the follicles in the ovaries to continue to mature. This, in turn, increases the likelihood that more than one egg will develop to maturity and be released during ovulation.

Most twins conceived with Clomid will not be identical. During clinical trials of twin pregnancies, one in five were identical twins and 80% of the twin pregnancies were fraternal twins (not identical).

Why aren't they identical? Clomid increases your odds of conceiving twins because your ovaries may ovulate more than one egg. Identical twins come from one egg— not two.

Other Factors That Up the Odds Having Twins

Fertility drugs aren't the only cause of multiple pregnancies. Even without Clomid, your odds of getting pregnant with more than one baby increase depending on factors such as your age, height, weight, and family history.

Using a higher dosage than necessary might increase the risk of having twins, but ironically, using a higher dosage of Clomid than you need can also lower your chances of getting pregnant at all. A higher dose can cause cervical mucus to be thicker, which makes it harder for sperm to travel through.

For that reason, when a doctor prescribes Clomid, they will start with the lowest dose. They will only increase the dose if the initial dose is not enough to trigger ovulation.

Women taking Clomid who do not have trouble ovulating or getting pregnant, as well as women younger than 25, might have an increased risk of getting pregnant with twins while taking Clomid.

How Will I Know If I Got Pregnant With Twins While Taking Clomid?

Symptoms of early pregnancy with twins are no different than singleton pregnancies. Having an early positive result on a pregnancy test or high levels of hCG on a blood test are also not reliable indicators of a twin pregnancy. You won't know if you conceived twins until you have an ultrasound. However, the ultrasound performed prior to ovulation may allow your doctor to guess your odds of conceiving twins based on the number of mature follicles.

Depending on your health history, your doctor may order an ultrasound at the six-week mark (two weeks after you miss your period)—though this might be too early to detect twins. A twin pregnancy should be visible by the eighth week, however.

What Should I Expect If I'm Expecting Twins After Clomid?

If you get pregnant with twins after taking Clomid, don't panic. Good prenatal care can reduce the odds of complications. Support from friends and family can help you make the most of this double blessing.

You may or may not need to see a high-risk OB specialist if you are expecting twins. A twin pregnancy can be followed by your regular OB-GYN. They might refer you to a specialist if complications arise.

Your doctor might want to monitor your twin pregnancy closer than they would with a singleton pregnancy.

There are increased risks for both the mother and baby with a twin pregnancy, and women with a history of infertility are at increased risk for preterm labor.

Your doctor will likely order an ultrasound for the last weeks of the first trimester to confirm whether the twins are sharing a placenta or sharing an amniotic sac.

The vast majority of twin pregnancies conceived with Clomid are fraternal twins, which means they will have their own placenta and own sac. However, identical twins can also be conceived with fertility drugs. Either way, it's important that you have an early ultrasound to determine if your twins are monochorionic or monoamniotic.

Twins who share a placenta but have separate sacs are known as monochorionic twins. Monochorionic twins are identical twins and come with higher risks. Up to 70% of identical twins share a placenta.

Twins who share a placenta and an amniotic sac are known as monochorionic-monoamniotic. It occurs in less than 1% of twin pregnancies and is significantly riskier than a monochorionic twin pregnancy.

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  1. American Society for Reproductive Medicine. Multiple Pregnancy and Birth: Twins, Triplets, and High Order Multiples (booklet). 2012.

  2. McDonald S, Murphy K, Beyene J, Ohlsson A. Perinatal outcomes of in vitro fertilization twins: A systematic review and meta-analyses. Am J Obstet Gynecol. 2005;193(1):141-152. doi:10.1016/j.ajog.2004.11.064

  3. U.S. Food and Drug Administration. CLOMID® (clomiphene citrate tablets USP). Sanofi-Aventis U.S. LLC. Updated October 2012.

  4. Glinianaia SV, Rankin J, Khalil A, et al. Prevalence, antenatal management and perinatal outcome of monochorionic monoamniotic twin pregnancy: A collaborative multicenter study in England, 2000-2013. Ultrasound Obstet Gynecol. 2019;53(2):184-192. doi:10.1002/uog.19114

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