Conceiving Twins While Taking Clomid

The Odds Are Lower Than You May Think

Mother holding twin baby boys
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Infertility 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. So if you're taking Clomid (clomiphene) 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.

For every 20 pregnancies conceived with Clomid, which is a pill taken by mouth to induce ovulation, the drug causes twin pregnancies between 5 and 8 percent of the time. That's fewer than one in 10 pregnancies or approximately one in 20 pregnancies. Your odds of conceiving triplets (or more) on Clomid is less than one percent. That's less than one in 100 pregnancies.

Why Clomid May Increase the Chance of Multiples

A woman's ovaries contain hundreds of thousands of follicles each containing 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 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, increasing 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, while 80 percent 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 eggs: 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 also may increase the risk of having twins. Ironically, using a higher dosage of Clomid than necessary also may lower the chances you'll get pregnant at all because it can cause cervical mucus to be thicker and harder for sperm to travel through. For that reason, when a doctor prescribes Clomid, she will start with the lowest dose. Only if that dosage doesn't trigger ovulation will she increase it.

Women taking Clomid who do not have trouble ovulating or getting pregnant, as well as women younger than 25, may 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 are no different with twin. Nor are an early positive result on a pregnancy test or having high levels of hCG on a blood test reliable indicators of a twin pregnancy. This means you won't know if you conceived twins until you have an ultrasound.

 Depending on your health history, your doctor may order one at the six-week mark (two weeks after you miss your period), but this may be too early to detect twins. However, by the eighth week, a twin pregnancy should be visible.

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


American Society of Reproductive Medicine. "Medications for Inducing Ovulation." March 10, 2017.

American Society of Reproductive Medicine. "Multiple Pregnancy and Birth: Twins, Triplets, and High Order Multiples." March 10, 2017.

Medline Plus. "Clomiphene." Sept 15, 2017.

Sanofi-Aventis. "Clomid Drug Information Sheet."