The science behind IVF and twin pregnancies

In vitro fertilisation (IVF) has revolutionised reproductive medicine, offering hope to couples struggling with infertility. One question that often arises during IVF consultations is: “Does IVF increase the chances of having twins?” The short answer is yes, but with important considerations that require closer examination. As IVF continues to play a significant role in assisted reproductive technologiesRead More

(ART), understanding its effect on the likelihood of twin pregnancies is key.

How IVF Works and the Role of Embryo Transfer

IVF is a process where eggs are fertilised by sperm outside the body in a laboratory setting. After the embryos develop, one or more are transferred into the uterus with the aim of achieving a successful pregnancy. The number of embryos transferred is a critical factor in determining the chances of twins or higher-order multiples.

Dr. Mannan Gupta, a gynecologist and IVF specialist, explains, “The primary objective of IVF is to achieve a healthy, successful pregnancy, and embryo transfer plays a vital role in this. By transferring multiple embryos, IVF aims to increase the chances of implantation, a factor that can result in twin or even multiple pregnancies.”

Why IVF Increases the Chances of Twins

The likelihood of twins with IVF can be influenced by various factors, with the most prominent being the number of embryos transferred during the procedure. Twin pregnancies in IVF are typically fraternal, known as dizygotic twins, which occur when two separate embryos implant and develop.

There are several reasons why IVF may increase the chances of twins:

Multiple Embryo Transfers: In the past, doctors often transferred more than one embryo to increase the chances of pregnancy. When both embryos implant, a twin pregnancy occurs. While this practice was common, the trend has shifted toward single embryo transfers to reduce risks.
Ovulation Stimulation: During certain IVF cycles, drugs are used to stimulate the ovaries, encouraging the release of more than one egg. This can lead to the fertilisation of multiple eggs and the possibility of twin pregnancies.
Embryo Splitting: A rarer occurrence, embryo splitting can result in identical (monozygotic) twins. This happens when a single embryo splits into two separate embryos after being implanted in the uterus. Although this is uncommon, it happens slightly more frequently in IVF pregnancies compared to natural conception.

Despite these factors, the health risks associated with multiple pregnancies are significant. Premature births, low birth weights, and complications during delivery can pose risks to both the mother and the babies. This has led many fertility clinics to adopt a more cautious approach.

The Shift Towards Single Embryo Transfer (SET)

In recent years, there has been a noticeable shift in IVF practices toward single embryo transfer (SET). This is especially true for younger women or those with high-quality embryos. Dr. Gupta notes, “We are increasingly advising patients to consider transferring just one embryo to reduce the risk of multiple pregnancies. This strategy is part of our commitment to ensuring patient safety while maintaining high success rates.”

While twin pregnancies may seem like an advantage – after all, it is seen as having “two for one” – the risks associated with carrying multiples are considerable. Premature birth, gestational diabetes, preeclampsia, and other complications are more common in multiple pregnancies. As a result, many clinics prefer SET to reduce these risks while still offering high chances of success.

The Chances of Having Twins with IVF

Statistically, the chances of having twins with IVF are significantly higher than with natural conception. In natural pregnancies, the chances of having twins are approximately 1 in 80. However, with IVF, especially when multiple embryos are transferred, the chances can rise to 20-30% or more, depending on factors like the number of embryos, the age of the mother, and the use of fertility drugs.

It is important to note that the decision to transfer multiple embryos is personalised based on the patient’s specific situation. If a woman has had several unsuccessful IVF attempts or if the embryos are of lower quality, transferring two embryos may be considered. However, this is done with careful medical supervision to ensure the safety of the mother and the babies.

Individualised IVF Treatment Plans

Every IVF journey is unique, and treatment plans should be tailored to meet the individual needs and health risks of each patient. As IVF technology evolves, doctors are focusing on ensuring the best possible outcomes while maintaining safety. For patients considering IVF, it is essential to have an open discussion with their fertility specialist about the number of embryos to transfer and the potential risks involved.

Conclusion

In summary, IVF does increase the chances of having twins, particularly when multiple embryos are transferred. However, as awareness of the risks associated with multiple pregnancies grows, many clinics now focus on single embryo transfers to ensure the best possible health outcomes for both mother and baby. If you are considering IVF, it’s crucial to work closely with your fertility specialist to develop a treatment plan that aligns with your needs and safety concerns.

Reference: https://www.bwhealthcareworld.com/article/one-baby-at-a-time-why-single-embryo-transfer-is-the-safer-ivf-choice-for-indian-couples-565486