Multifetal Pregnancy Reduction

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Multifetal Pregnancy Reduction

Topic Overview

Multifetal pregnancy reduction (MFPR) is a procedure used to reduce the number of fetuses in a multiple pregnancy, usually to two. When a pregnancy involves three or more fetuses (high-order pregnancy), the risks of miscarriage, stillbirth, and lifelong disability increase with each additional fetus.

Assisted reproductive technology (ART) and fertility drugs have greatly increased the number of multiple pregnancies.

The goal of MFPR is to increase the chance of a successful, healthy pregnancy. Multifetal pregnancy reduction:

  • Is usually done early in a pregnancy, between the 9th and 12th weeks.
  • Is most often performed when there are four or more fetuses present.
  • Can be used to reduce triplets to twins.
  • Is known as "selective termination" when it involves a fetus with severe defects or one that is expected to die later in the pregnancy, which would threaten the life of the surviving fetus or fetuses.

A multifetal pregnancy reduction improves your chances of avoiding miscarriage, carrying your pregnancy longer, and delivering one or more healthy babies:1

How does a triplet-reduced-to-twin pregnancy compare with a triplet pregnancy?

Births and losses of twins after MFPR

Births and losses of triplets (no MFPR)

Percent of planned babies born, taken home



Premature birth before 32 weeks



Premature birth before 28 weeks



Miscarriage before 24 weeks



One or more fetal deaths during the pregnancy

27 out of 1,000

92 out of 1,000


The most common method of fetal reduction is transabdominal MFPR. For this procedure, the doctor uses ultrasound as a guide and inserts a needle through the woman's abdomen and into the uterus to the selected fetus. The doctor injects the fetus with a potassium chloride solution, which stops the fetal heart from beating.

Because it is very small during the first trimester, the dead fetus is usually absorbed by the mother's body. This may include some vaginal bleeding. This absorption process is the same process that happens in the vanishing twin syndrome.


The risks of multifetal pregnancy reduction include:

  • Miscarriage of the remaining fetuses. Of pregnancies with three, four, or five fetuses, about 5% of pregnancies miscarry after being reduced to twins.2 But overall the risk of a fetal death is higher for a triplet-or-more pregnancy than after having MFPR.1, 3 See the table above.
  • Premature birth. But this risk is lower than it is for a triplet-or-more pregnancy.1, 3 See the table above.
  • Infection of the abdomen or uterus (rare).

What to think about

The Society of Obstetricians and Gynaecologists of Canada (SOGC) and the Canadian Fertility and Andrology Society (CFAS) recommend careful use of infertility treatment in the effort to avoid the risks of a triplet-or-more pregnancy and of MFPR.4 When embryos are transferred to the uterus, this means limiting the number of embryos that are transferred for each treatment cycle.

Couples who have conceived three or more fetuses are faced with the possibility of losing one or more fetuses or infants, raising one or more disabled children, or both.

If you are considering assisted reproductive technology (ART), fertility drugs, or both, talk to your doctor about how you can avoid a triplet-or-more pregnancy. You can decide how many embryos you want transferred for each cycle. Transferring fewer embryos decreases your chance of having twins, triplets, or more. The decision to have a multifetal pregnancy reduction is difficult and traumatic. If you are faced with this decision, talk to your doctor about the relative risks of carrying your multiple fetuses to term versus choosing MFPR. Think about discussing your decision with a counsellor or spiritual advisor.



  1. Wimalasundera R, et al. (2003). Reducing the incidence of twins and triplets. Best Practice and Research Clinical Obstetrics and Gynaecology, 17(2): 309–329.
  2. Stone J, et al. (2002). A single center experience with 1,000 consecutive cases of multifetal pregnancy reduction. American Journal of Obstetrics and Gynecology, 187(5): 1163–1167.
  3. Strauss A, et al. (2002). Multifetal gestation—Maternal and perinatal outcome of 112 pregnancies. Fetal Diagnosis and Therapy, 17(4): 209–217.
  4. Allen VM, et al (2006). Pregnancy outcomes after assisted reproductive technology. Joint SOGC–CFAS Guideline No. 173. Journal of Obstetrics and Gynaecology Canada, 28(3): 220–233.


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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