IVF Twins & Multiple Pregnancies: Causes & Risks

How Twin Pregnancy Happens in IVF?

Twin pregnancy with IVF can happen in two main ways.

Dizygotic or Fraternal Twins	Monozygotic or Identical Twins
In this case, two separate embryos implant and grow together. This is more likely when two or more embryos are transferred during the same IVF cycle.	In this case, a single embryo splits into two after transfer. Even if only one embryo is transferred, there is still a small chance of identical twins.

Although twin pregnancy is possible even in case of single embryo transfer, the chances remain low. IVF has a higher twin rate than natural conception, largely because more than one embryo may be transferred during treatment.

What Are the Chances of Twins in IVF?

The chances of twins with IVF are higher than with natural conception, but they are not guaranteed. In natural pregnancies, the chance of twins is about 1 to 2 %. With IVF, the overall twin rate ranges between 10 and 30%, depending on several factors.

The main reason IVF twins are more common is embryo transfer. When more than one embryo is transferred into the uterus, the chance of twins increases. Even with a single embryo transfer, twins are still possible due to embryo splitting.

So if you are asking, can you have twins with IVF, the answer is yes. But modern fertility practice focuses more on healthy singleton pregnancies than multiple pregnancies.

Early Symptoms of Twin Pregnancy After IVF

Some women may experience stronger symptoms in case of a twin pregnancy than in a single pregnancy, but they are not always reliable indicators. They may include intense nausea, vomiting, fatigue, breast tenderness, or early abdominal bloating. Higher hormone levels can also sometimes cause stronger pregnancy symptoms.

However, symptoms alone cannot confirm twins. Ultrasound remains the most reliable way to detect a twin pregnancy, usually around six to seven weeks after embryo transfer.

How Many Embryos Are Required for a Twin Pregnancy?

The number of embryos transferred plays a major role in the IVF twins rate. Doctors decide this carefully based on age, embryo quality, and previous IVF outcomes.

Chances of Twins With 1 Embryo

The chances of a twin pregnancy with single embryo transfer are very low, around 1 to 3%. The cases of identical twins are high in this case due to a single embryo being split. Single embryo transfer offers the safest outcome and is now considered best practice in many fertility clinics.

Chance of Twins With 2 Embryos

The chance of twins with the transfer of 2 embryos increases significantly, often ranging from 15 to 30%. Though the risk of triplets is low, it is not completely impossible. Due to these factors, two embryo transfers are usually reserved for selected cases only.

Chance of Twins With 3 Embryos

Transferring three embryos greatly increases the risk of twins and higher-order multiples. This practice is now uncommon due to safety concerns and strict guidelines. Most modern clinics avoid transferring three embryos unless there are exceptional medical reasons.

Is Twin Pregnancy After IVF Safe for the Mother and Babies?

Twin pregnancy after IVF can result in the birth of healthy babies, but it generally carries more risks than a singleton pregnancy. When a woman carries two babies, her body needs to support the growth and development of both, which can increase the chances of certain pregnancy complications. These include premature birth, high blood pressure, gestational diabetes, and low birth weight.

However, this does not mean that every twin pregnancy will experience complications. The outcome depends on several factors, including the mother’s health, age, pregnancy history, and whether the twins share a placenta. Regular prenatal check-ups, timely ultrasounds, and appropriate medical care help doctors monitor the pregnancy and identify potential problems early.

Women who conceive twins through IVF may need more frequent monitoring throughout pregnancy. Their doctor may recommend a personalised care plan based on the babies’ growth, the mother’s health, and the type of twin pregnancy.

1. What Are the Health Risks of Twin Pregnancy for the Mother?

Carrying twins can place additional physical demands on the mother’s body. Compared with a singleton pregnancy, a twin pregnancy is associated with a higher risk of certain complications, including:

• High blood pressure and preeclampsia: Women carrying twins have a higher risk of developing high blood pressure during pregnancy. Preeclampsia is a related condition that can affect the mother’s organs and may require early delivery.
• Gestational diabetes: Hormonal changes and the increased demands of pregnancy can raise the risk of developing diabetes during pregnancy.
• Anaemia: The body needs additional iron to support the growth of two babies. If iron levels are insufficient, the mother may develop anaemia.
• Greater physical discomfort: Twin pregnancies may cause more fatigue, nausea, back pain, pelvic pressure, and difficulty sleeping as the pregnancy progresses.
• Increased likelihood of caesarean delivery: Depending on the babies’ positions, their health, and the mother’s condition, a caesarean birth may be recommended.

These risks do not mean that complications are inevitable. Regular antenatal visits, recommended blood tests, blood pressure monitoring, and guidance on nutrition can help manage many pregnancy-related concerns. The doctor will determine the appropriate monitoring and treatment according to the mother’s individual needs.

2. What Are the Risks of Premature Birth in IVF Twin Pregnancies?

Premature birth, also called preterm birth, occurs when a baby is born before 37 completed weeks of pregnancy. It is one of the most common complications associated with twin pregnancies. More than half of twin pregnancies result in birth before 37 weeks, although the timing and outcome vary from one pregnancy to another.

In IVF twin pregnancies, the risk of premature birth is an important consideration because babies may need additional medical support if they are born before their organs have fully developed.

Some potential complications associated with premature birth include:

• Breathing difficulties: Babies born early may have underdeveloped lungs and may need respiratory support.
• Low birth weight: Premature babies may weigh less than babies born at full term, and some may need help with feeding and maintaining body temperature.
• Feeding difficulties: Babies born prematurely may have difficulty coordinating sucking, swallowing, and breathing.
• Increased risk of infection: Their immune systems may be less developed, making them more vulnerable to infections.
• Long-term developmental concerns: Some babies born very prematurely may experience difficulties with learning, movement, vision, or hearing as they grow.

The level of risk depends largely on how early the babies are born, their birth weights, and their overall health. Some premature babies need only short-term support, while others may require care in a neonatal intensive care unit (NICU).

To monitor these risks, doctors may recommend regular ultrasounds to assess the babies’ growth, closer monitoring for signs of preterm labour, and a delivery plan based on the progress of the pregnancy. If early delivery becomes likely, the medical team may provide treatments to support the babies’ development and arrange specialised newborn care when needed.

The key takeaway: Twin pregnancy after IVF requires careful medical supervision, but many women have healthy pregnancies and deliver healthy babies. Attending all prenatal appointments and following the advice of a fertility specialist and obstetrician can help support the health of both the mother and the babies.

Understanding hCG Levels in IVF Twin Pregnancies

Human chorionic gonadotropin, commonly called hCG and pregnancy hormone, is measured in blood tests to confirm pregnancy after IVF. In twin pregnancies, hCG levels are often higher than in single pregnancies because more than one embryo is producing the hormone. However, hCG levels alone cannot confirm whether a pregnancy is a twin pregnancy. A pelvic ultrasound performed around six to seven weeks of pregnancy is the only reliable way to confirm twins after IVF.

Doctors use hCG trends mainly to check if a pregnancy is progressing normally, not to diagnose twins. There is a wide overlap between hCG levels seen in single and twin pregnancies.

Approximate hCG Levels Seen in Twin Pregnancies After IVF:

Time After Embryo Transfer	Single Pregnancy Range (IU/L)	Twin Pregnancy Range (IU/L)
12 days post transfer	50 to 200	100 to 300
14 days post transfer	100 to 400	200 to 600
5 weeks of pregnancy	500 to 7,000	1,000 to 10,000
6 weeks of pregnancy	1,500 to 30,000	10,000 to 50,000

Key Note: The above values are only general observations. It is possible that some single pregnancies may show higher hCG levels, while some twin pregnancies may fall within normal single pregnancy ranges.

Pros and Cons of Multiple Pregnancies

Pros

• One pregnancy to complete family goals
• Emotional satisfaction after infertility
• Siblings grow together

Cons

• Higher medical risks for the mother and babies
• Increased chance of preterm delivery
• More frequent medical monitoring
• Longer hospital stays for newborns

Due to the risks involved, doctors focus on healthy outcomes rather than higher numbers.

Risks Associated With Twin Pregnancy in IVF

A twin pregnancy can bring joy to many couples; however, it is associated with more medical risks compared to a single pregnancy.

• Risks for mother: These include high blood pressure, gestational diabetes, anaemia, and a higher likelihood of caesarean delivery. Also, pregnancy discomforts are generally more intense with twins.
• Risks for babies: Twin pregnancies are more prone to preterm birth, low birth weight of babies, and admission to the neonatal intensive care unit.

These are the reasons why many fertility experts advise single embryo transfer in most cases, especially for younger patients with good quality embryos.

How to Minimise the Risk of Twin Pregnancy in IVF?

Preventing twins in IVF is often part of modern fertility planning. Below are some ways in which a twin pregnancy can be avoided during an IVF procedure:

• Single embryo transfer is the most effective method that many specialists prefer.
• Careful embryo selection using advanced lab techniques also helps maintain high success rates with one embryo.
• Frozen embryo transfer protocols further reduce risks without compromising pregnancy chances.
• Patients are encouraged to discuss their family goals openly with their fertility specialist before embryo transfer.

Factors Affecting the Chances of Twins in IVF

A number of factors can influence the chances of twins during IVF. These are:

• Age, as younger women have higher implantation rates.
• Embryo quality significantly affects success and twin chances.
• The number of embryos transferred directly increases the likelihood of twins.
• Assisted hatching and blastocyst transfer slightly increase the chance of identical twins.
• Previous IVF outcomes and uterine health also matter.