IVF Twins: How Common Are They Really?
Global twin rates are on the rise, largely due to the increased prevalence of in vitro fertilization and other fertility methods. In the last 40 years, the birth rate of twins born throughout the world has grown by one third.
Access to reproductive health services is a major contributing factor to twin birth rates. In the U.S., twinning rates have grown 71% since the 1980s. In parts of Europe, such as the UK and Scandinavia, this issue is being addressed with educational campaigns promoting single embryo transfers.
Here's what you need to know about IVF twins and what factors actually contribute to this growing global phenomenon.
Does IVF cause twins?
In vitro fertilization itself doesn't automatically increase the twin rate. It's the method used that increases the chance of twins with IVF. Here's how it breaks down.
During an IVF procedure, eggs are retrieved from the patient and fertilized with sperm to create embryos. From there, one or more embryos are transferred back into the woman's uterus in hopes of creating a successful pregnancy.
Low egg quality can be a contributing factor to infertility, particularly as a woman gets older. To improve the chances of success with a viable embryo, some fertility treatment plans include transferring multiple embryos in one cycle. As you can imagine, if there is more than one viable embryo in the group, then it's possible for a multiple birth.
You can lower the chances of twins with IVF by opting for a single embryo transfer, but talk to a specialist about the pros and cons of each scenario. Your fertility doctor is the best resource to create a plan that makes sense for your individual health needs.
How common are twins born through IVF treatment, compared to naturally conceived twins?
Approximately 1 in every 250 births is a pair of twins conceived naturally. That's roughly a 0.04% chance of having twins without any fertility treatment involved. Identical twins are even rarer, accounting for only 3 or 4 of every 1,000 births. Both genetics and age can increase your chances of naturally having fraternal twins.
The IVF twins percentage is much higher. Studies show that the chance of multiples with fertility treatment is anywhere from 30% to 40%. Within that number, IVF contributes to about 17% of those twins.
Between 1980 and 2014, twin births rose from 1 in 53 births to 1 in 29 births. At the same time, IVF twin rates are declining as technology improves. One study showed that in 1998, the IVF twin birth rate was 30%, but dropped to 9.7% in 2018. Even higher multiple births caused by IVF (such as triplets) decreased from 7% to 0.2% during the same period.
Are there any benefits to having twins born through IVF treatment instead of naturally conceived twins?
Even though there is a higher chance of twins with IVF, there are actually better health outcomes compared to twins that are naturally conceived. These benefits include:
Lower risk of birth defects: Because IVF can involve embryo chromosomal screening prior to the embryo transfer, there is a lower risk of birth defects, dropping from 3 to 5% in natural births to just 1% in IVF births.
Lower risk of miscarriage: Miscarriages are frequently caused by an embryo's chromosomal abnormalities. The embryo chromosomal testing process in IVF can provide a greater ability to select the healthiest embryos to reduce the risk of miscarriage.
What factors can increase the likelihood of having twins through IVF treatments?
IVF itself isn't the only contributor to a higher chance of twins. Here are some other factors that can increase the likelihood of having twins during your IVF treatment.
The mother’s age: As women age, their bodies tend to produce more follicle stimulating hormone, which can lead to more eggs dropping during ovulation. Paired with IVF, this can lead to a higher chance of twins as well.
The father’s age: Some studies indicate that the age of the father may also increase the chance of twins, although research is not yet conclusive.
Family history: Genetics play a role in the likelihood of twins, particularly non-identical twins. You could be as much as 2.5 times likely to have twins if you or any of your siblings are non-identical twins.
The use of fertility drugs: Some fertility drugs add to the chance of multiple gestation, particularly clomiphene, which induces ovulation.
The use of assisted reproductive technologies (ART): Any type of fertility treatment typically comes with an increased chance of multiples, including twins.
Ethnicity: Ethnicity can also impact the chance of twins. African American women are most likely to have twins, while Caucasian women are most likely to have higher multiples, such as triplets. Native American and Asian women in the U.S. are the least likely to have twins.
Is there more or less risk attached with having IVF twins compared to a single IVF pregnancy?
Unfortunately, there is a higher risk for several types of complications during an IVF twin pregnancy versus a single IVF pregnancy. During pregnancy with twins or other multiples, there's a higher rate of the following medical risks:
Preeclampsia: A serious blood pressure condition that may arise in week 20 of pregnancy or later.
Gestational diabetes: A case of diabetes that occurs only during pregnancy in women who suddenly develop insulin resistance.
Intrauterine growth restriction (IUGR): A condition in which the baby does not grow in the womb as expected.
Placental abruption: When the placenta detaches from the uterus before labor.
Fetal demise/loss: The death of the fetus while still in the womb.
There is also higher risk during labor and birth when a woman is pregnant with IVF twins, including:
Higher rates of Cesarean birth
Low birth weights
It's important to work with a specialist who can help determine the best embryo transfer plan to minimize the chance of multiple births, while still making the most of your IVF. Oma is committed to finding the ideal balance to reach those fertility goals while also fully supporting the mother's health and well being.