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 increase the chance of twins?
In vitro fertilization (IVF) is a popular fertility treatment, and many people wonder about the likelihood of having twins with this method. So, does IVF increase the chance of twins? While the IVF procedure itself doesn't directly increase the twin rate, certain factors can lead to higher chances of twins with IVF. Let's take a closer look at how this happens.
During an IVF cycle, 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 achieving a successful pregnancy. It's important to understand that the IVF twin rate is mainly affected by the number of embryos transferred.
Low egg quality can contribute to infertility, especially as a woman ages.To improve the chances of a successful pregnancy with a viable embryo, some fertility treatment plans may involve transferring multiple embryos in one cycle. As you might expect, if more than one viable embryo is transferred, the chances of twins with IVF increase, potentially leading to multiple births.
You can lower the IVF twin rate by opting for a single embryo transfer (SET). However, it's crucial to consult with a fertility specialist to discuss the pros and cons of each scenario. Your fertility doctor is the best resource for creating a personalized plan that addresses your individual health needs and optimizes your chances of achieving a healthy pregnancy, whether that involves having twins or a singleton.
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?
While the IVF procedure itself doesn't directly increase the twin rate, certain factors can contribute to a higher chance of IVF twins. Let's explore some of these factors that can increase the chances of twins with IVF treatments:
The mother’s age: As women age, their bodies tend to produce more follicle-stimulating hormone (FSH), which can lead to the release of multiple eggs during ovulation. When combined with IVF, this can increase the chances of having twins as well.
The father’s age: Although research is not yet conclusive, some studies indicate that the father's age may also play a role in the likelihood of twins with IVF. Further studies are needed to confirm this connection.
Family history: Genetics can influence the chances of having twins, particularly fraternal (non-identical) twins. If you or any of your siblings are fraternal twins, you could be as much as 2.5 times more likely to have twins through IVF.
The use of fertility drugs: Certain fertility medications, such as clomiphene, can increase the chance of multiple gestations. These drugs induce ovulation, which may result in more than one egg being released, increasing the chances of twins with IVF.
The use of assisted reproductive technologies (ART): IVF and other fertility treatments often come with an increased chance of multiples, including twins. The specific ART used and the number of embryos transferred can have a significant impact on the percentage of twins resulting from IVF.
Ethnicity: Ethnic background can also affect the likelihood of having IVF twins. African American women have the highest chance of having twins, while Caucasian women are more likely to have higher-order multiples, such as triplets. Native American and Asian women in the U.S. are the least likely to have twins through IVF.
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
Preterm labor/deliver
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.
Last Updated: Jun 16, 2023 12:00 AM
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