You may have heard stories of IVF ending in multiple pregnancies (hello, Octomom!), but does it really have an impact on having multiples? Learn the science behind IVF and multiple pregnancies, and if twins are seemingly more likely via IVF than natural conception. But first, let’s talk about twins and what can naturally increase the chances of multiple pregnancies.
Types of Twins
Identical Twins
Identical twins involve a single egg being fertilized by a single sperm. Somewhere along the way, the fertilized egg divides into two, resulting in identical twins. The chances of having identical twins are relatively rare – around 3 or 4 in every 1,000 births. And while it may be obvious, identical twins are always the same sex, either both boys or both girls, at birth. Why? Well, they don’t just look alike, they also share the exact same DNA.
Fraternal Twins
Fraternal twins result when two separate eggs are fertilized by two separate sperm cells. Both fertilized eggs implant into the uterus, and 9 months later, two babies are born. Fraternal twins can either be two boys, two girls, or a boy and girl. They may or may not look a lot alike. That’s because, unlike identical twins, they don’t share the exact same DNA. In fact, aside from age, they’re no more similar than brothers and sisters born years apart.
Natural Factors that Affect Having Twins
Genetic Hyperovulation
Hyperovulation, which is a situation where the body releases two or more eggs during ovulation, can be passed down in your DNA from your mom’s genes – or even your dad’s.
Age
Women over 35 have a higher chance of conceiving twins. Hormonal changes that happen as you near menopause may encourage the body to release more than one egg during ovulation.
Height
Taller women seem to have a higher rate of having twins. While this may sound a bit strange, researchers credit a certain insulin-like growth factor with this possibility.
Race
Black women deliver twins at a higher rate than white women, according to 2018 birth statistics in the United States. But Asian and Hispanic women deliver twins at a lower rate than the other groups listed.
Previous Pregnancies
Previous pregnancies may increase your chances of having twins. In fact, women between the ages of 35 to 40 with four or more children are three times more likely to have twins than a woman under 20 without children.
Does IVF Cause Twins?
The process of IVF, or in vitro fertilization, does not necessarily lead to a substantially higher chance of multiple pregnancies. Statistically, women who undergo IVF have multiple pregnancies (twins, triplets, or more) at a higher rate than women who conceived naturally. The rate of twin pregnancies with IVF with fresh embryos is 12.1% for women under age 35 and 9.1% for women ages 35 to 37, compared to the natural occurrence rate of 2% in the general population. The chances decrease with age (unlike natural twin conception), as women 38 to 40 only have a 5.3% rate of twins through IVF. And for those who are 43 and older, the rate is just 0.5%.
The main reason for the seemingly higher occurrence rate of twins through IVF is the practice of transferring more than one embryo at a time in an IVF cycle. Until recently, most fertility doctors routinely transferred multiple embryos in the hope of achieving a better chance of success. Placing two or more embryos into the uterus at a time was thought to increase pregnancy rates, with the hope that at least one would survive. Quite often, more than one embryo will successfully implant, resulting in a multiple pregnancy.
Some couples choose to transfer just one. While the single embryo might split and turn into identical twins, this isn’t too likely. In a similar, less likely situation, for those who do choose to transfer two embryos during IVF, say one of those embryos splits and then all three implant in the uterus. The result would be triplets – two identical twins and one fraternal sibling.
What to Consider with Multiple Pregnancies
While having twins may sound like the kind of two-for-one deal any couple would love to have, especially after experiencing infertility, it really is best to aim for one healthy baby. Potential risks with multiple pregnancies and births include preeclampsia, gestational diabetes, intrauterine growth restriction (IUGR), placental abruption, fetal demise/loss, higher rates of Cesarean birth, preterm labor or delivery, and low birth weights. Your doctor can reduce the odds of multiples with careful monitoring and single-embryo transfer during IVF.
If you are considering fertility treatments to conceive, schedule an appointment with a fertility doctor to talk about twins. Two bundles of joy are certainly something to look forward to, and we have happily helped deliver some healthy and adorable twins into the world! But it is still important to speak with a fertility specialist to understand the expectations and risks when having twins. Reach out to Red Rock Fertility Center today to learn more about twins with IVF and how we can help you grow your family.
FAQs
The rate of twin pregnancies with IVF with fresh embryos is 12.1% for women under age 35 and 9.1% for women ages 35 to 37, compared to the natural occurrence rate of 2% in the general population.
Are you more likely to have twins with IVF? ›
Statistically, women who undergo IVF have multiple pregnancies (twins, triplets, or higher-order multiples) at a higher rate than women who conceived naturally: According to statistics published in 2013, around 40% of all IVF pregnancies in the US resulted in multiple births.
What are the best fertility pills to get pregnant with twins? ›
Clomiphene (Clomid) and letrozole (Femara) are fertility medications that stimulate ovulation. These medications are given during IUI cycles. They may cause your body to produce multiple eggs — leading to multiple eggs being fertilized, resulting in twin pregnancies.
How common are twins with fertility drugs? ›
Clomid (clomiphene), a pill taken by mouth to induce ovulation, causes twin pregnancies between 5% and 12% of the time. 1 That's fewer than one in 10 pregnancies. Your odds of conceiving triplets (or more) on Clomid is even lower: less than 1% (less than one in 100 pregnancies).
Are IVF babies from the same cycle considered twins? ›
Twins generally means that they are born at the same time. "But, yes, twins in that they have come from the same batch of embryos, collected from the same treatment cycle. Twins born at a different time – but not a twin pregnancy when they have grown in the womb together."
How to increase odds of twins? ›
Factors that increase your odds of having twins naturally
- Genetics. You may have heard that twins “run in families.” This is partially true. ...
- Age. Are you over age 35? ...
- Height. Taller women seem to have a higher rate of having twins. ...
- Weight. ...
- Race.
- Diet. ...
- Previous pregnancies.
Blastocyst stage (days 4–8) division results in monochorionic-diamniotic twins. Division at the 8–12-day stage results in monochorionic-monoamniotic twins, and division after day 12 leads to conjoined twins [1, 2].
What to eat to conceive twins? ›
In a study conducted by Dr. Gary Steinman, females who eat more dairy are 5 times more likely to have a twin pregnancy. Various studies also showed that vegans are less likely to conceive twins. So, the best chance is to increase the intake of dairy and meat in order to increase your chances of having twins.
Can you do anything to help conceive twins? ›
Some fertility drugs work by stimulating a woman's ovaries, which can sometimes cause them to release more than one egg. If sperm fertilizes both of these eggs, this can result in twins. In vitro fertilization (IVF) can also increase the chance of conceiving twins.
What is the best fertility drug to get pregnant? ›
Clomiphene and letrozole are often first-choice fertility pills. Both can be effective for treating infertility. But studies suggest that letrozole may be the more effective option for people with PCOS-related infertility.
You're 35 or older
As you age, your chance of conceiving twins increases. Researchers have found that women over 35 produce more follicle stimulating hormone (FSH) than younger women, which may cause more than one egg to drop at ovulation.
Who carries the gene for twins? ›
The gene for hyperovulation can come from either side of the family, but the woman would need to have the gene in order for the couple to have twins based on genetics. In other words, twins on the father's side of the family will have no influence on your chances of having twins.
Are frozen embryos more likely to split? ›
The prevalence of true zygotic splitting was 1.36%, and the researchers found that, compared to singleton pregnancies, using frozen-thawed embryos increased the risk of zygotic splitting embryos by 34%, maturing the blastocysts in the lab for a few days before embryo transfer increased the risk by 79%, and assisted ...
Is there a higher chance for twins with IVF? ›
When looking across all age groups, the odds of having a multiple gestation pregnancy through IVF is roughly 30 percent, with the large majority of those being twin pregnancies. Your odds are primarily based on the number of embryos transferred and the patient's age.
Can I ask for twins with IVF? ›
Yes, a couple can ask for twins, but the clinic will counsel on the risks. The main risk with IVF is pre-term births. Pre-term births account for 60% of twin deliveries and bring a host of complications for the babies.
When are IVF twins usually born? ›
A little more than half of twin pregnancies end in preterm delivery (before 37 weeks). While 40 weeks is the full gestation period of the average pregnancy, most twin pregnancies are delivered at approximately 36 weeks (range 32-38 weeks depending on the type of twin pregnancy).
Are IVF embryos more likely to split? ›
This occurs rarely in spontaneous conceptions also but the overall occurrence of zygote splitting is more in IVF cycle as compared to spontaneous conception. The reason of zygote splitting more in IVF is not exactly known but various studies suggest increased manipulation of embryo in laboratory .
What are the disadvantages of IVF babies? ›
IVF raises the risk of having more than one baby. Becoming pregnant with multiple babies carries higher risks of pregnancy-related high blood pressure and diabetes, early labor and delivery, low birth weight, and birth defects than does pregnancy with a single baby. Birth defects.
Who is more likely to have twins? ›
Older age– Women over 30 have a greater chance of multiple conception. Many women today are delaying childbearing until later in life, and may have twins as a result. High parity – Having one or more previous pregnancies, especially a multiple pregnancy, increases the chances of having multiples.
What percentage of IVF babies are female? ›
Sex bias. In their study, the likelihood of an IVF birth resulting in a boy was between 53% and 56%, depending on how soon the fertilised egg was put back into the woman. Taking the higher value, this would mean that in every hundred births, 56 would be baby boys and 44 would be girls.
