Infertility Treatment: Risks of Multiple Pregnancy

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Infertility Treatment: Risks of Multiple Pregnancy

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Risks during multiple pregnancy

With each additional fetus a pregnant woman carries, health risks to her and her fetuses increase.

Health risks in a multiple pregnancy. If 100 women* were pregnant with the following conditions, the average number that would experience... 1

Gestational diabetes is:

Preeclampsia is:

Preterm labour is: Preterm birth is:
One fetus 3 6 15 10
Twins 5–8 10–12 40 50
Triplets 7 25–60 75 92
Quads 10 or more 60 or more 95 or more 95 or more

* A risk for 1 person out of 100 is equal to a 1% risk.

Your chances of conceiving a multiple pregnancy

In the general population, less than 3% of births involve twins, triplets, or more. By contrast, your chances of conceiving a multiple pregnancy increase when you use fertility drugs and assisted reproductive technology (ART).

Currently, about 20% of multiple pregnancies occur naturally, while the other 80% are the result of using fertility drugs or assisted reproductive technology.2 The majority of these pregnancies are twins, but there are also more triplets (or more) than in the general population. The incidence of triplets or more can be controlled during in vitro fertilization by reducing the number of embryos transferred, but this is not possible with superovulation. Risks of multiple pregnancies are 5% to 8% with clomiphene and superovulation.3 The risks are even higher with gonadotropins.2

Ovulation stimulation

While clomiphene increases the likelihood of pregnancy with one or two fetuses, gonadotropins increase the risk of conceiving twins or more. Researchers continue to search for a dependable way to use gonadotropins, yet effectively prevent triplet-or-more pregnancies.

Balancing ART treatment success versus the risk of conceiving a multiple pregnancy

The risk of conceiving a multiple pregnancy is directly related to the number of embryos transferred to a woman's uterus. However, the chances of embryo or fetal loss increase as a woman ages from her mid-30s into her 40s. In order for a woman over age 35 to maximize her chances of conceiving with her own eggs and carrying a fetus to term, she typically has more embryos transferred than does a younger woman. This practice, however, increases her risk of conceiving multiple fetuses.

Because of the risks of multiple pregnancy to the babies, experts recommend limiting the number of embryos transferred. Based on your age and your situation, your doctor will recommend a certain number of embryos to be transferred.

Women over 40 have a high rate of embryo loss when using their own eggs. As an alternative, an older woman may choose to use more viable donor eggs.

Related Information



  1. American Society for Reproductive Medicine Practice Committee (2006). Multiple pregnancy associated with infertility therapy. Fertility and Sterility, 86(Suppl 4): S106–S110.
  2. Burney RO, et al. (2007). Infertility. In JS Berek, ed., Berek and Novak's Gynecology, 14th ed., pp. 1185–1275. Philadelphia: Lippincott Williams and Wilkins.
  3. Speroff L, Fritz MA (2005). Induction of ovulation. In Clinical Gynecologic Endocrinology and Infertility, 7th ed., pp. 1175–1213. Philadelphia: Lippincott Williams and Wilkins.


By Healthwise Staff
Primary Medical Reviewer Sarah Marshall, MD - Family Medicine
Specialist Medical Reviewer Femi Olatunbosun, MB, FRCSC - Obstetrics and Gynecology
Last Revised April 27, 2010

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