How many embryos should be transferred? Risks of multiple pregnancy explained

When undergoing IVF treatment, one of the most important decisions couples face is how many embryos should be transferred. While transferring more embryos may seem like a way to increase success rates, it also raises the risk of multiple pregnancy, which can have serious health implications for both mother and babies.

Understanding the balance between success and safety is key to making the right decision.

What does embryo transfer mean in IVF?

Embryo transfer is the final step of the IVF process where one or more embryos are placed into the uterus. The goal is to achieve a healthy pregnancy with the highest chance of success and lowest risk.

Advancements in IVF technology now allow doctors to select the best-quality embryo, making it possible to achieve success even with a single embryo.

How many embryos should be transferred?

The number of embryos transferred depends on several factors:

• Woman’s age.
• Embryo quality.
• Previous IVF failures.
• Medical history.
• Genetic testing results. (PGT-A)

General medical recommendations:

• Women under 35: Single embryo transfer (SET) is usually recommended.
• Women 35–40: One or two embryos may be considered.
• Women above 40: Two embryos may be transferred in some cases.

Today, many leading IVF centres encourage Single Embryo Transfer (SET) to reduce risks while maintaining good success rates.

Why transferring more embryos is not always better?

It’s a common misconception that more embryos mean higher success. In reality:

• Success rates do not increase proportionally.
• The risk of twins or triplets rises significantly.
• Complications become more likely.

Modern IVF focuses on quality over quantity.

What is multiple pregnancy?

Multiple pregnancy occurs when more than one fetus develops in the uterus (twins, triplets, or more). While it may sound exciting, medically it is considered a high-risk pregnancy.

Risks of multiple pregnancy for the mother

Multiple pregnancies can increase complications such as:

• High blood pressure. (preeclampsia)
• Gestational diabetes.
• Increased chance of cesarean delivery.
• Excessive bleeding during or after delivery.

These risks can affect both short-term and long-term maternal health.

Risks of multiple pregnancy for babies

Babies from multiple pregnancies face higher risks, including:

• Premature birth.
• Low birth weight.
• Developmental delays.
• NICU admission.
• Increased risk of long-term health issues.

In severe cases, complications can be life-threatening.

Benefits of single embryo transfer (SET)