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Understanding The Risks Of IVF Twins

Being pregnant with twins, triplets, or an even higher number of multiples comes as a big surprise to most moms-to-be. Having IVF twins is a real possibility because fertility treatments like IVF can increase the risk of twins or other multiples. “Risk” might seem like an odd word to describe what many people would view as a blessing, but the truth is that multiple pregnancies can be risky for both the mother and the fetuses. Here’s what you need to know about the risks of IVF twins or multiples.

The Demand of Conceiving Twins

Despite the risks involved, some parents-to-be want IVF twins and actively try to conceive multiples. There are a few reasons for this.

First, IVF is quite expensive, so some parents-to-be think that conceiving twins amounts to a sort of two-for-one deal. If someone hopes to have a larger family, the thought of twins can be appealing. Most doctors discourage actively trying to conceive IVF twins or other multiples because of the increased risk involved.

The American Society of Reproductive Medicine (ASRM) has guidelines recommending that only one embryo be transferred during IVF specifically to avoid the possibility of multiples. Today, more fertility clinics are following that recommendation and won’t try implanting more than one.

Still, some patients request that multiple embryos be transferred because they can’t stand the thought of going through the whole cycle only to have an embryo fail to implant. With two or more being transferred, the chances of success go up.

At the end of the day, a doctor can’t guarantee the outcome of any IVF cycle, let alone guarantee that someone will become pregnant with twins. They can, however, determine how to best minimize risk while balancing the patient’s wishes.

How Common Is It To Have Twins?

According to ReproductiveFacts.org, when conception occurs naturally (without fertility treatments), twins are the most common type of multiple pregnancy, accounting for approximately one in 250 pregnancies. Triplets occur once in every 10,000 pregnancies, and quadruplets only naturally occur in about one in every 700,000 pregnancies.

What about Identical Twins?

The chance of having identical twins is actually the same for everyone, more or less. The rate of identical twins is about 1 in 250 pregnancies, or 3-4 per 1000 pregnancies. Identical twins are totally random, so your chances of having one fertilized egg spontaneously split into two separate embryos is the same regardless of your race, age, weight, or other factors.

What Can Cause Multiple Pregnancies?

In natural multiple pregnancies, the cause of fraternal twins is almost always hyperovulation. This means that a woman’s body tends to release more than one egg during ovulation. Fraternal twins or triplets occur when two or three eggs are fertilized by two or three separate sperm. The zygotes develop separately alongside one another in the uterus. Hyperovulation can be caused by many different factors, which we will discuss below.

Identical twins are completely random, on the other hand. They’re the result of a single fertilized egg splitting into two, or rarely, three parts. So far, we don’t know exactly why this happens, although scientists have been searching for the answer. No definitive cause for identical twins has been discovered yet.

A major cause for multiple pregnancies is the use of fertility treatments and medications. These treatments, like IVF, promote hyperovulation, and therefore the likelihood of having twins or higher-order multiples increases.


Older women are more likely to experience hyperovulation, increasing their chances for having twins or multiples. The chances increase at age 30 and again at age 35. This is mainly due to hormonal changes that occur as you age. Those hormones can signal your body to release more than one egg at a time, meaning women of advanced maternal age are more likely to have twins or multiples.

Family History

You may have heard that “twins run in families.” There is actually no evidence for this common misconception. In reality, it has to do with the type of twin (fraternal vs. identical) and whose side of the family you’re talking about, the mother’s or the father’s.

If your mother or sister had fraternal twins, she may have a gene that causes hyperovulation, meaning that her body tends to release more than one egg during ovulation. That increases the likelihood that you also have that gene. In that case, your chance of having fraternal twins is about double that of other women. Fraternal twins or multiples on the male’s side of the family don’t really affect your chances, and because identical twins are completely random, that’s not a predicting factor either.


Women who have a BMI of 30 or greater are at an increased risk for having multiples. The reason for this seems to be because excess fat can increase a person’s estrogen levels, which in turn can cause hyperovulation.


Though scientists aren’t entirely sure why, taller women tend to have a higher rate of twins than others. One theory is that the extra space in the womb allows for multiples to develop and thrive. A study in 2006, published in the Journal of Reproductive Medicine, found that women who had twins or multiples naturally were 5 foot 5 inches on average, while the average height for all women in the United States was 5 foot 3 ¾ inches.


If you happen to conceive while breastfeeding (yes, it’s possible!), you may have an increased chance of having twins. Scientists aren’t entirely sure why, but studies have shown that women who get pregnant while still breastfeeding a child are up to nine times more likely to have twins.


The types of foods that you consume may also increase your chances of having twins. If you consume a lot of dairy, some studies show that your likelihood of having twins is increased. It’s hypothesized that this is because cows release hormones into their milk that can increase levels of insulin growth factor in the human body. Some other evidence to support this theory is a 2006 study that found women who ate a vegan diet, as in no dairy at all, had twins at ⅕ the rate of women who had dairy in their diets.

Other dietary clues can be found in southwest Nigeria, which has one of the highest rates of naturally conceived twins in the world. Researchers decided to try and find out why, so they analyzed several factors, including diet among the people in that population. Yams emerged as a possible cause for twins. The Yoruba people of southwest Nigeria typically consume a lot of this root vegetable, which happens to contain a natural hormone (phytoestrogen) that can stimulate hyperovulation.

The Risks of Multiple Pregnancies

Despite the fact that a quick Google search will reveal lots of articles aimed at women who want to have twins, a multiple pregnancy of any number is risky. A twin pregnancy is much more likely to have complications, including possible harm to the mother and the babies. Because of this, the American Society for Reproductive Medicine (ASRM), along with many doctors and fertility clinics across the country, discourage people from actively trying to have twins or multiples.

Some of the risks of a twin or multiple pregnancy include:

Premature Birth

Nearly ⅔ of all twins are born prematurely, with an average gestation of 35 weeks. Full term is 37 weeks and beyond. Premature birth puts babies at risk for all sorts of complications, including immature lung development, feeding problems, and stomach and intestinal problems. Premature babies often require medical supports such as ventilation and a stay in the NICU (neonatal intensive care unit) for close medical monitoring. Premature babies can experience lasting complications as well, including learning disabilities, cerebral palsy, hearing and vision loss, respiratory problems, and other developmental delays.

Infant Death

There is a significantly higher rate of miscarriage in twin pregnancies than in single pregnancies. Vanishing twin syndrome occurs in 36% of known twin pregnancies before week 12, and in 50% of pregnancies with three or more known gestations. This is when one of the embryos in a multiples pregnancy spontaneously aborts, leaving one or more to develop normally.

Twin-to-Twin Transfusion Syndrome

Identical twins are at risk of unequal growth and development in the womb. Twin-to-twin transfusion syndrome is when one twin grows much slower than the other, often with one twin taking more blood flow from the placenta than the other. Without treatment, it can lead to infant heart failure and death of one or both twins. This occurs in around 10 percent of all identical twin pregnancies when they share the same placenta.

Low Birth Weight

Low birth weight is one of the most common complications with twin and multiple pregnancies. More than half of all twins are born under 5.5 pounds. Low birth weight can cause many health complications for newborns and infants, and it can also lead to ongoing health and developmental problems.

Birth Defects

According to the March of Dimes, multiples are twice as likely as singleton babies to have birth defects such as congenital heart problems, neural tube defects like spina bifida, and cerebral palsy.

Apart from the health problems and risks that are increased for the babies, mothers carrying multiples are also at risk for several complications during pregnancy and during labor and delivery.

Cesarean Section

Women who are pregnant with multiples are much more likely to have a cesarean birth (c-section) than women who are pregnant with one baby. A c-section, while relatively common and safe, is a major abdominal surgery that takes longer to recover from and can cause complications in future pregnancies.


Your chances for developing gestational hypertension, and/or preeclampsia is almost double when pregnant with multiples. High blood pressure during pregnancy can be very dangerous, leading to premature labor, maternal death, and fetal death. The only way to cure preeclampsia is to deliver the baby. If that’s not possible due to the gestational age of the fetuses, the condition becomes life or death for the mother, the babies, or both.

Gestational Diabetes

Women who are pregnant with multiples are also twice as likely to have gestational diabetes than women carrying singleton pregnancies. This condition can be treated with lifestyle and diet changes, but there can be serious complications if untreated. Gestational diabetes can cause excessive weight gain, increased risk for c-section, high blood pressure, premature labor, and it can increase the weight of the baby, making delivery more difficult.

How It Can Double The Expenses

People who are considering or undergoing IVF treatment often look at a multiple embryo transfer as a way to increase the odds for becoming pregnant IVF twins or multiples. They see it as a sort of “two-for-one” deal. If they can get pregnant with two babies at once, they feel like they can save on the cost of trying again with another cycle. But is there really a cost savings when getting pregnant with IVF twins?

It turns out, it can actually cost much more to have twins than to pay for additional IVF cycles. An IVF cycle costs $12,000 on average. A study in 2013 found that it costs roughly $21,000 to have a give birth to a singleton baby, and that rate skyrockets to $105,000 for twins and more than $400,000 for triplets or higher. That difference could account for lots of IVF cycles!

What makes a multiple pregnancy so much more expensive? Mostly, it’s the added cost to care for babies who will likely be premature, low birth rate, or experience other complications.

More than 60% of all twins, and nearly 100% of triplets or higher multiples will be born premature. Premature babies almost always require a stay in the NICU, sometimes for several months until their lungs and other organs have developed enough to survive outside of the hospital. Multiple pregnancies are more likely to require a c-section, which costs more than a vaginal delivery and includes a longer hospital stay for both the mom and the babies.

Increased health risks to the mother during pregnancy mean she’ll have more frequent doctor appointments, is more likely to be placed on bed rest or admitted to the hospital, and other medical interventions. All told, it costs 5-10 times more to have a multiple pregnancy than it does to have a single pregnancy.

And what about those pursuing parenthood via surrogacy? Intended parents can expect to pay their gestational surrogate a premium should she become pregnant with multiples. The surrogate needs to be compensated to account for the increased risks and discomforts of carrying twins or more, so you can expect to pay $5,000-$20,000 or more, plus the added medical costs that come with any twin or multiple pregnancy.

Interested in learning more about surrogacy? Learn more at FamilyInceptions.com.

Medical expenses aside, the cost of raising twins is more than raising single children who were born at separate times simply because there are a lot of expenses you can’t stagger. You’ll need two cribs, two sets of clothing, double the diapers and formula. You’ll possibly be paying for childcare for two infants at once. They’ll both reach college age at the same time.

The $12,000 you may have saved with a single vs. a follow-up round of IVF isn’t starting to sound like much of a price tag anymore, is it?

The Myths With IVF Twins

How likely is it to have IVF twins anyway? It turns out, there’s a lot of myth around the prevalence of IVF twins, especially today as assisted reproductive technology has evolved.

It’s actually much less common to have IVF twins in 2021 than ever before. Reproductive endocrinologists and fertility clinics are much more focused on transferring a single embryo at a time. This is in large part due to the risks associated with multiples, but it’s also a testament to the fact that the science has gotten so good, we are now better able to predict an embryo’s chance of being successful. Doctors have modern techniques to maximize the potential for pregnancy with a single embryo, such as blastocyst stage culture, where the blastocyst is grown in the lab for five days and observed as it reaches an optimal stage of development.

With single embryo transfer success rates of 60% and higher, it’s becoming less necessary or desirable to transfer more than one embryo. Transferring two or more embryos doesn’t really increase your odds that much; statistics show that transferring one embryo at a time for two cycles is actually more successful overall.

Getting Fraternal Twins through IVF

Fraternal twins are more likely among patients receiving IVF or other fertility treatments. The average rate of twins among all births is about 3%. With IVF, it’s 5-12% depending on the age of the mother. Certain fertility medications such as gonadotropins can increase the chance of twins to 30%. Drugs like Clomid and Femera give you a 5-12% chance as well.

Identical Twins through IVF

IVF and fertility treatments don’t really affect your chances of getting identical twins. The average general rate is 0.45%; with treatment, it’s 0.95%. This increase isn’t very significant because identical twins happen spontaneously, randomly, and without known cause.

Chances Of Getting Twins Through Treatments

With IVF or other fertility treatments, the rate of twins varies based on the type of treatment and the age of the mother, but it can increase anywhere from 5% higher to 30% higher chance for having twins with IVF or fertility treatments. Odds are increased usually because these treatments and medications stimulate egg production, encouraging more than one egg to be released during ovulation.

With IVF, the chance for multiples increases greatly if more than one embryo is transferred at a time. Overall, women undergoing IVF treatment have a 5-12% chance of having multiples, which is significantly higher than the average rate of 3% found in naturally conceived pregnancies.

Having A Single Pregnancy Is A Lot Safer

Most medical professionals are in agreement: a single pregnancy is much safer than a twin or multiple pregnancy. The added risks and costs associated with twins, triplets, or higher order multiples are great enough to cause most in the field to discourage actively trying for multiples. That said, many twins are born healthy of course, so if mother nature decides to make it happen for you, you’re in for a wild ride!

When In Doubt, Consult

It’s always best to consult with your medical team and reproductive health professionals. Only a licensed medical professional can give you advice about what’s best for you, your unique health situation, and your family building goals.

Ask your doctor about the risks vs. benefits of having IVF twins or multiples as you consider the question of single vs. multiple embryo transfer and other important decisions.

We should be thankful for the IVF treatment, learn about it from our other article!

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