One of the most common questions couples ask before IVF is: “Will IVF give us twins?” The simple answer is: No, IVF does not automatically result in twins.

IVF can increase the chance of twins only when more than one embryo is transferred into the uterus. With modern IVF, better embryo culture, blastocyst transfer and freezing techniques, the aim is increasingly to achieve the safest outcome: one healthy baby at a time.

Why Were Twins More Common With IVF Earlier?

In the past, IVF success rates were lower and embryo selection was less accurate. Doctors often transferred two or three embryos in the hope that at least one would implant. This increased pregnancy rates in some situations, but it also increased the chance of twins and, occasionally, triplets.

Today, IVF laboratories are better able to culture embryos to the blastocyst stage, usually Day 5 or Day 6. A blastocyst has already shown the ability to continue developing in the laboratory and may have a higher implantation potential than an earlier cleavage-stage embryo.

This allows many patients, especially younger women with good-quality embryos, to have a single blastocyst transfer with an excellent chance of pregnancy.

When Is Single Embryo Transfer Preferred?

For a young woman in her first IVF cycle, with a good ovarian reserve, good-quality embryos, a healthy uterus and no major male-factor concern, transferring one good blastocyst is often the best approach.

A single embryo transfer reduces the chance of twins while still offering a strong chance of pregnancy. It also allows any remaining embryos to be frozen for future use. If pregnancy does not happen with the first transfer, another frozen embryo can be transferred later without repeating the full IVF stimulation and egg retrieval process.

To understand how age, egg quality, sperm quality and uterine factors influence the chance of IVF success, you may also read our article on IVF success rate and the factors that influence it.

When Might More Than One Embryo Be Transferred?

There are selected situations in which transferring more than one embryo may be discussed. These may include repeated failed embryo transfers, advanced maternal age, poor embryo quality, low implantation potential or a history of several unsuccessful IVF cycles.

In such cases, the decision is individualized after discussing the possible benefits and risks. The number of embryos transferred depends on the woman’s age, embryo stage, embryo quality, previous IVF outcome and medical history.

In many settings, the upper limit used in selected cases is usually up to three cleavage-stage embryos or up to two blastocysts. However, this is not a routine target, especially in young women with good-prognosis embryos. The objective is not simply to obtain a positive pregnancy test; it is to achieve a healthy pregnancy with the lowest possible risk to both mother and baby.

What Are the Risks of Twins?

Twins may sound appealing to some couples, particularly after a long fertility journey. However, twin pregnancy is medically more demanding than a singleton pregnancy.

Twin pregnancies have a higher risk of miscarriage, high blood pressure, gestational diabetes, premature delivery, low birth weight, neonatal intensive-care admission and complications around delivery. The risks are even higher with triplets or higher-order pregnancies.

Therefore, a successful IVF cycle should not be measured only by whether pregnancy occurs. The ideal result is a healthy mother and a healthy baby delivered safely.

Can Twins Occur After Single Embryo Transfer?

Yes, but it is uncommon. Even when only one embryo is transferred, it can rarely divide after transfer and result in identical twins. This is a natural biological event and cannot always be predicted.

However, the likelihood of twins is much lower after transfer of one embryo than after transfer of two or more embryos.

In a good-prognosis IVF cycle, the chance of a positive pregnancy may be around 60–70% per embryo transfer in selected younger patients. Even then, most successful pregnancies are singletons. Multiple pregnancies usually remain a minority and are mostly twins, although the exact percentage varies depending on embryo stage, number of embryos transferred, age and embryo quality.

The Right Goal in IVF

IVF should not be planned with the assumption that twins are better. A carefully selected single blastocyst can offer a strong chance of pregnancy while reducing the risks associated with multiple pregnancy.

At Advance Fertility & Gynecology Centre, the number of embryos transferred is decided after a detailed review of age, embryo quality, previous IVF history, uterine factors and the couple’s individual circumstances. The goal is always to maximise the chance of a healthy pregnancy while keeping treatment safe.

You may also find our article on fresh versus frozen embryo transfer in IVF useful when planning the next stage of treatment.

References

1. Practice Committee of the American Society for Reproductive Medicine; Practice Committee of the Society for Assisted Reproductive Technology. Guidance on the limits to the number of embryos to transfer: a committee opinion. Fertil Steril. 2021;116(3):651-654.
2. ESHRE Guideline Group on the Number of Embryos to Transfer. ESHRE guideline: number of embryos to transfer during IVF/ICSI. Hum Reprod. 2024;39(4):647-686.
3. Lawlor DA, Nelson SM. Effect of age on decisions about the number of embryos to transfer in IVF. BMJ. 2012;345:e6293.
4. Kamath MS, Mascarenhas M, Franik S, et al. Single versus multiple embryo transfer for women undergoing assisted reproductive technology. Cochrane Database Syst Rev. 2020;8:CD003416.
5. Banerjee K, Singla B. Correlation of visualization of post embryo transfer air bubble with pregnancy rate. J IVF-Worldwide. 2023;1(4). doi:10.46989/001c.89303.
6. Banerjee K, Singla B. Impact of general anesthesia during embryo transfer on pregnancy outcomes. Int J Sci Res. 2021;10(2):63-64.