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Multifetal Pregnancies

Osher Ben-Or, Midwife, Carmel Medical Center
22 February 2026

Multifetal pregnancy is pregnancy with more than one fetus. Over the last few decades there has been an increase in the number of multifetal pregnancies, even though they are still considered a relatively rare phenomenon.

There are various reasons for the increase in the prevalence of these pregnancies: Family history, obstetric history, older maternity age, in-vitro fertilization and fertility treatments.

A multifetal pregnancy presents higher risk for the development of medical complications (both for the mother and the fetuses) and is classified as a high-risk pregnancy. Therefore, it is important that you follow strict pregnancy monitoring to detect risks as early as possible, and also to maintain proper nutrition and desired weight gain. Since gestational diabetes and hypertension diseases are more common in multifetal pregnancies, there is great importance in continuous monitoring of your blood pressure during this pregnancy, monitoring the presence of protein in your urine and undergoing blood tests to detect gestational diabetes.    

Ahead of your delivery date, you will be requested to seek medical consultation in order to plan your delivery date and delivery method.

There are several factors that the physicians will address: 

  • The number of fetuses
  • The presentation of each fetus
  • The fetuses' weight and size
  • Your age at the time of this pregnancy
  • Your overall health

In any case, it is important to remember that a multifetal pregnancy usually occurs earlier than expected, and many times require caesarean section.

Multifetal pregnancy is a pregnancy with more than one fetus. Even though pregnancies with twins, triplets and even more are a relatively rate phenomenon, the number of multifetal pregnancies has been increasing over the last few decades.

In a multifetal pregnancy, it is natural that you and your partner will feel mixed feelings. On the one hand, great excitement ahead of your double bundle of joy, especially if you've been waiting for this pregnancy for a long time; and on the other hand, feelings of worry and concern about the normal progress of this pregnancy as a high-risk pregnancy.

While it may be true that a multifetal pregnancy significantly increases the risk for complications, the good news is that with the advances in obstetric medicine, there has been great progress in the ability to manage these complications, to deliver early and to treat babies who were born prematurely. All of these factors brought about a significant improvement in the survival of fetuses in multifetal pregnancies.

Who has a higher chance of a multifetal pregnancy

There are a number of factors that can increase your chances of becoming pregnant with multiple fetuses:

  • Family history
  • Obstetric history
  • Age of conception
  • In-vitro fertilization
  • Fertility treatments
  • Family history: If other women in the family had a history of multifetal pregnancies.
  • Obstetric history: If this woman had a history of multifetal pregnancies. 
  • Age of conception: Aged 30 and older.
  • In-vitro fertilization: By this process, more than one lab-grown fetus is returned to the mother's body. Nowadays it is no longer commonplace to return more than 2 fetuses.
  • Fertility treatments: The use of fertility medications to induce ovulation usually causes more than one egg cell to be released from the ovaries, which increases the chances for a multifetal pregnancy. 

Types of multifetal pregnancies

There are two types of situations where multifetal pregnancies occur (the same principle is identical in both twins, triplets and more):

  • Division of a fertilized egg cell in two or more

    Fetuses are created by the fertilization of one egg cell by a single sperm cell and the subsequent division of this egg cell into two fetuses or more. These fetuses carry an identical genetic material, and therefore they will always be of the same sex. In pregnancy with identical twins (or more), there can be separate amniotic sac and placenta for each fetus or a joint placenta.

    Why is this important? If there is a joint placenta, the risk for complications increases and therefore closer monitoring is required.

  • Fertilization of more than one egg cell

    In this case, more than one egg cell has been released from the ovaries and each of them has been fertilized by a different sperm cell. Therefore, each fetus has its own placenta and amniotic sac. We are talking about siblings who develop together without sharing the same genetic material.

Monitoring a multifetal pregnancy

A multifetal pregnancy requires you to maintain close and frequent monitoring and early detection of complications that result from this type of pregnancy. Sometimes hospitalization is required and even early delivery.

During the first trimester, when performing your first ultrasound test, your physician will be able to determine with a high level of reliability the type of your pregnancy, namely if this is a pregnancy with identical twins or non-identical twins. This assessment is important so you can receive a recommendation about the nature of pregnancy monitoring required and its frequency. This monitoring will also include specific reference to early detection of complications that can occur in higher prevalence in your type of pregnancy.

Tests during a multifetal pregnancy

Almost all pregnancy tests that are administered in a single-fetus pregnancy are also administered in multifetal pregnancy.

It is important that you know that in a multifetal pregnancy, the results of the biochemical screening that will be conducted during the first and second trimester are not precise. The blood tests that will be administered to you cannot give you separate values for each fetus, and therefore each fetus will undergo a nuchal translucency test and the risk will be determined by the weighing of the nuchal translucency results and the mother's age.

If necessary, you will receive a recommendation to undergo diagnostic genetic tests (chorionic villus sampling (CVS) or amniocentesis).

Due to higher risk for gestational diabetes and hypertension (high blood pressure) diseases in a multifetal pregnancy, it is especially important to maintain regular monitoring of your blood pressure during this pregnancy, presence of protein in your urine and screening tests for gestational diabetes.

Your primary care physician may recommend that you take a glucose challenge test (GCT) at an earlier time. If you have additional risk factors, you may receive a recommendation to take a diagnostic screening test for gestational diabetes (Oral glucose tolerance test (OGTT)).

Possible risks in a multifetal pregnancy

A multifetal pregnancy significantly increases the risk for pregnancy complications. As stated above, every multifetal pregnancy is considered a high-risk pregnancy.

These are the possible complications:

Almost all possible pregnancy complications in regular pregnancies occur in greater prevalence in a multifetal pregnancy, such as gestational diabetes or hypertension diseases. The greater the number of fetuses, the higher the prevalence of complications.

There are certain risks and complications linked with the presence of more than one fetus during pregnancy. Pregnancy with multiple fetuses who share a joint placenta is at higher risk for complications related to the allocation of resources and complications related to the development of fetuses during the pregnancy. Pregnancy with multiple fetuses who share a joint amniotic sac has been found to pose greater risks for complications related to the umbilical cord.

The most common complication. Multifetal pregnancies are at greater risk for early delivery (before the 37th week), and the more fetuses, the greater the risk. The reason for early delivery is sometimes a medical need to end the pregnancy earlier than expected in order to prevent complications. It can also occur naturally due to the increased pressure on the uterus and the cervix. Early delivery sometimes leads to need for intensive treatment due to complications related to preterm delivery (the earlier the gestational age, the greater the risk for complications related to preterm birth). These complications include difficulty breathing, difficulty maintaining body temperature, bleeding in the central nervous system and more.

Newborns in multifetal pregnancies are at greater risk to be born at a low birth weight. This can be caused by both early delivery and by factors related to the uterus (insufficient place for fetal growth, placental insufficiency and increased competition on nutrients between the fetuses).

In addition to all of the above, it is important to remember that each pregnancy is unique and that there are also individual circumstances. Your gynecologist who monitors your pregnancy will know to fit you with the necessary framework for monitoring, its frequency and additional tests that you need to take, according to your condition and the progress of your pregnancy.

Delivery date and method in a multifetal pregnancy

Within the framework of your pregnancy monitoring, your gynecologist will instruct you when you should visit the medical center in which you are expected to deliver, in order to decide on the delivery date and method.

When you arrive for consultation about the delivery method, there will be several factors that the physicians will address when advising you, such as the number of fetuses (pregnancies with triplets and more typically end in a caesarean section), the presentation of each fetus (when the lead fetus is not in a cephalic presentation, the chances of a caesarean section increase), their size, their weight and their overall health, your age at the time of conception and your overall health. All of these factors will be taken into consideration when you receive consultation about the delivery method.

You should remember that things may change over the course of the delivery, so that even if you decided on an attempt at a normal vaginal delivery, sometimes it may be necessary to end the pregnancy in a caesarean section.

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