What Is the Clomid Success Rate for Ovulation and Pregnancy?

When Clomid Works Best and When It Doesn't


Verywell / Chelsea Damraksa  

Clomid's (clomiphene citrate) primary purpose is to induce ovulation in women who are either not ovulating or ovulating irregularly. Between 70% and 80% of women will resume ovulation from treatment with Clomid.

Of course, ovulation is only step one. Your chance of getting pregnant over several cycles of Clomid use is approximately 30%. If you don't conceive after six months, it's time to move onto another treatment.

First Month Efficacy

Depending on which research studies you reference, the odds of conceiving during any one Clomid treatment cycle are 5.6% to 20%. The effectiveness of Clomid varies depending on the cause of infertility.

Keep in mind that those with no fertility problems have about a 25% chance of getting pregnant in any given month. If you don't get pregnant after one month, don't panic. Needing more than one cycle is common. In fact, the average time to conceive for people between ages 30 and 36 is about a year.

Odds of Getting Pregnant

A literature review published in Human Reproduction considered several studies on Clomid. Altogether, the Clomid success rates for just over 5,000 women were included. In this study, they found that...

  • 73% eventually ovulated on Clomid
  • 36% eventually achieved pregnancy
  • 29% gave birth

The birth rate is lower than the pregnancy rate due to miscarriages. Clomid doesn't seem to increase the risk of miscarriage.

However, Clomid success is also dependent on why you can't get pregnant. Clomiphene citrate can work well for those with ovulation problems. But what if ovulation isn't an issue?

Another study, this one from Scotland, looked at success rates for couples diagnosed with unexplained infertility. Couples were randomly assigned to one of three groups: "expectant management," treatment with just Clomid, or treatment with unstimulated intrauterine insemination (IUI).

The most effective treatment group was the IUI group, who achieved a 22% live birth rate. The Clomid only treatment group was 14% and the couples who received no treatment at all had a 17% birth rate.

The Best Day to Start Clomid

Clomid is taken for five days. Treatment can be started as early as on Day 2 of the menstrual cycle or started on as late as Day 5. However, most doctors either have you take Clomid on days 3, 4, 5, 6, and 7, or they have you take it on days 5, 6, 7, 8, and 9.

Does it matter which protocol your doctor chooses? Yes and no. In order to induce ovulation, treatment follows the Day 5 through 9 option. If your doctor wants to "enhance" ovulation, you'll likely take Clomid on Days 3 through 7.

When it comes to pregnancy and ovulation success rates, however, studies have not found an advantage or disadvantage.

Your odds of getting pregnant are similar no matter which Clomid start date protocol your doctor prefers for you.

After Six Months

If Clomid doesn't help you get pregnant after six months, your doctor should suggest you try something else. There are a few reasons for this.

One, if Clomid hasn’t helped you conceive after six months, the odds of it working on month seven or eight are very low. Remember that your fertility naturally declines with age. If something isn't working, it's best to move on.

Secondly, extended treatment with Clomid may lead to fertility problems of its own. Women who have gone through several Clomid cycles may have thinner endometrial linings, which can impede with embryo implantation. (This will correct itself after time away from Clomid and is not a long-term adverse effect.)

Some early research on Clomid found a possible increased cancer risk in women treated for more than six cycles. To mitigate this risk, you should not take Clomid for more than six cycles.

Optimal Dosage

Your doctor will likely start you on the lowest dose first, which is 50 mg. If you don’t ovulate on 50 mg, your doctor may try one more cycle at the same dose, or increase your dosage by 50 mg. 

If your doctor does need to increase your dosage, don't worry that this is a bad sign. One study found that only 46% of women will ovulate at 50 mg. Another 21% will ovulation if they are given 100 mg, and another 8% if given 150 mg.

If you do ovulate, and you just don’t get pregnant, then your doctor will keep you at the dose you’re on. Increasing the dosage doesn’t increase your odds of getting pregnant. In fact, higher doses of Clomid may lead to side effects, some of which can reduce your fertility.

One possible side effect of Clomid is thickened cervical mucus. Cervical mucus is vital to fertility and helps the sperm survive the vaginal environment and make their way into the uterus and eventually to the egg.

Other possible side effects you should be aware of include hot flashes, headaches, bloating, the risk of a multiple pregnancy (conceiving twins), developing ovarian cysts, and visual disturbances. Higher dosages can also increase your risk of developing ovarian hyperstimulation syndrome. If you're concerned about any side effects you're experiencing, as always, contact your doctor.

Your doctor will want you on the lowest possible dosage, just enough to trigger ovulation, but not more than that.

When Clomid Doesn't Work

Clomid is not the magic fertility drug that some people mistake it to be. It works well in the right circumstances—but it can be completely unsuccessful in the wrong ones. If there are additional problems besides irregular or absent ovulation, or there are any male factor infertility issues that have not been addressed, success will be lower.

It's questionable how successful Clomid therapy is for couples diagnosed with unexplained infertility. Also, Clomid does not always work well for women who are dealing with age-related infertility, with low estrogen levels, or women with primary ovarian insufficiency (formerly known as premature ovarian failure.) It may also not work in women whose ovulation problems are caused by a thyroid issue.

Women who are obese may have better success with Clomid if they lose weight. Whether or not you should take the time to lose weight before starting treatment depends on your age and how obese you are. Discuss the best course of action with your doctor.

What If I Don't Ovulate?

If you don't even ovulate while taking Clomid, there are some things your doctor can try before suggesting other treatments.

For women with PCOS, the cancer drug letrozole (Femara) may be more successful at triggering ovulation than Clomid. Taking Clomid along with the diabetes drug metformin has also increased success rates for some women.

If Clomid does help you ovulate, but after six months of treatment you still have not gotten pregnant, the next step may be a referral to a fertility clinic (if you're not already being seen at one). Or, your doctor may suggest gonadotropins (injectable fertility drugs).

A Word From Verywell

Remember that while you may be primarily familiar with Clomid and perhaps IVF treatment, there are, in fact, many more fertility treatment options for you to consider. Always talk to your doctor if you’re concerned about the next step or if Clomid isn't working as you hoped it would.

7 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  6. Althuis MD, Moghissi KS, Westhoff CL, et al. Uterine cancer after use of clomiphene citrate to induce ovulation. Am J Epidemiol. 2005;161(7):607-615. doi:10.1093/aje/kwi084

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Additional Reading

By Rachel Gurevich, RN
Rachel Gurevich is a fertility advocate, author, and recipient of The Hope Award for Achievement, from Resolve: The National Infertility Association. She is a professional member of the Association of Health Care Journalists and has been writing about women’s health since 2001. Rachel uses her own experiences with infertility to write compassionate, practical, and supportive articles.