It’s a common notion that IVF causes twins.
There are popular examples, media, and even studies out there that support the idea of IVF twins.
It’s a personal choice to want or not want twins.
But it’s another to navigate the fact that your fertility treatment could result in twins.
But do all IVF cycles cause twins?
And if not, what are the chances?
That’s exactly what we’re going to answer, along with a deep dive into the type of twins, the chances, and a better understanding of whether your IVF cycle has a higher chance of twin conception or not.
In this article: 📝
- Does IVF increase the chance of twins?
- How common are twins with IVF?
- Can you choose twins with IVF?
- How to avoid twins in IVF
- Why are identical twins more common with IVF?
- Can IVF twins be different genders?
- When does an embryo split into twins IVF?
- Will I have twins in my IVF cycle?
Does IVF increase the chance of twins?
Even with IVF, the chance of twins with a single embryo is less, compared to having two embryos transferred.
But it’s important to note that when we talk about “twins” here, there are two main types, and the statistics differ for each:
- Fraternal twins or non-identical twins: In IVF, this happens when two embryos are implanted in the uterus. They’re non-identical twins, since each egg was fertilized with a different sperm to form two unique embryos.
- Identical twins: In IVF, this happens when a single embryo splits to grow and develop into two fetuses. They’re identical twins, since when a single egg splits into two, the same genetic material is in both fetuses.
How common are twins with IVF?
According to the HFEA, the rate of twins with IVF has reached an all-time low of 1 in 20 births.
Twins with IVF are fairly common globally, but the rate has been steadily reducing.
This is because regulatory bodies worldwide are opting to make single embryo transfers the norm.
And, interestingly, the CDC has recently reported that the overall percentage of twin pregnancies in the US has also reached a low of 6.4%.
What are the chances of twins with 2 embryos in IVF?
According to studies, the chances of twins with 2 embryos in IVF were found to be 11% with both good quality embryos, 4.8% with one good quality embryo, and 2% with no good quality embryos.
And there are things that you bring to the table that can affect your chances of IVF twins, too — if you’re over 35 and a good endometrium (the lining of the uterus), for example
Can you choose twins with IVF?
Surprisingly, yes, you can choose to have twins with IVF!
If your IVF cycle has two good-quality embryos ready for transfer, you can consent to have a double embryo transfer, although it’s not as common in IVF procedures anymore.
There are some risks with a twin pregnancy, which your healthcare provider will also explain before a double embryo transfer.
A double embryo transfer also doesn’t guarantee IVF twins, but it will increase your chances.
Can you pay for IVF to have twins?
You won’t have to pay more, no.
Your IVF cycle payment won’t change if you want a single embryo transferred or double, since you’ll be billed for the entire embryo transfer procedure.
So if you want to have twins with IVF, it’s worth talking to your fertility clinic.
How to avoid twins in IVF
To avoid twins in IVF, the best choice is to opt for a single embryo transfer.
The likelihood of having twins with a double embryo transfer is higher compared to a single embryo transfer.
This is also the standard protocol in many clinics across the UK and the US, although it’s always worth asking how many embryos they’re planning to transfer.
Until recently, the protocol was more toward double embryo transfers, in the hope of improving the chances of at least one embryo implanting itself in the uterus.
But over time, due to the increase in multiple births and the risks it carries, especially with increased female age, institutions like the HFEA are working with clinics to make single embryo transfer the mandate.
In the US, the ASRM also guides healthcare professionals to opt for single embryo transfer in women under and above 35.
Why are identical twins more common with IVF?
But there’s no single factor that we can pinpoint as the cause — some of the potential causes of identical twins in IVF cycles could be:
- If a double embryo transfer was carried out.
- If a fresh embryo transfer was carried out, instead of a frozen embryo transfer.
- If ICSI was the preferred method of fertilization.
- If assisted hatching was carried out — this is a process where, right before your embryo transfer, a small portion of the protective layer of the embryo is removed or dissolved using a laser. The idea is that this headstart should help the embryo come out of its shell, and implant in the uterus lining, once transferred.
- If embryos were transferred on day 5 of your cycle. But even with single embryo transfer, if the embryos are transferred at day 2-3 after assisted hatching, the chances of twins are higher.
- If donor eggs were used for a double embryo transfer. For example, a 35-year-old using self-eggs for a double transfer during IVF, would have a lower chance of twins compared to using donor eggs. This is because egg donors are usually younger, with little to no fertility issues, to increase the chance of implantation with each embryo.
While these are some lab and procedure-related factors, some patient-related factors can also impact the chances of twins in IVF cycles:
- Higher BMI (Body mass index)
- Optimal endometrial thickness (the lining of the uterus that helps with the embryo housing itself in the uterine wall)
- Unexplained infertility
But these are speculated patient-related causes — there are currently no studies to support these as causes of IVF twins.
Can IVF twins be different genders?
This is because two different embryos develop to form two different babies.
Identical IVF twins of different sexes are rare, since a single embryo splits to create two embryos with identical genetic material, and in most cases, of identical genders.
When does an embryo split into twins IVF?
When a single embryo “splits”, it results in identical twins, which, some studies suggest, often happens in the 4-8 day stage.
But, depending on the day of embryo growth that it splits, it can result in twins that either share or don’t share their placentas and amniotic sacs.
Will I have twins in my IVF cycle?
Honestly, it’s a mix of the number of embryos transferred, your age, and sometimes, just pure chance.
There are cases where a single embryo transfer has led to twins, and double embryo transfers have resulted in a single live birth.
Essentially, every IVF journey is unique, and so is yours.
Whatever the situation, or your decision, you don’t have to go through it alone.
We’re here for you.