Chances of having Twins with IUI

IUI twins

The Chances of Having Twins with IUI Insemination Treatment

It’s not uncommon to have twins when you go through fertility treatment. You hear that repeatedly.

Many people often ask us whether this also applies to IUI insemination treatment. Do our clients have twins after IUI? Yes, it does happen. However, the chances of having twins with IUI are very low.

In the years 2021 and 2022, 7 pairs of twins were born after insemination treatment (IUI) in our clinic. This means that only 1.2% of all successful IUI treatments resulted in a multiple pregnancy.

Maria and Nicole are one of the couples who have had twins after IUI treatment in our fertility clinic. You can read their story here.

In the following, we explain when the chances of having twins is increased during IUI treatment and why it is extremely rare for us to experience this in Diers Klinik.

What is IUI?

Insemination treatment is also known as IUI, which is an abbreviation for intrauterine insemination. This means that during the treatment, sperm cells that have been washed are introduced into the uterus with the help of a catheter. Insemination (IUI) is the gentlest option when it comes to fertility treatment.

You can find out more about how IUI insemination works here at Diers Klinik.

The IUI treatment is particularly suitable for women who are in good health and have no fertility issues.

In our clinic, we therefore treat the following women/couples in particular:

  • Single women

In 2022, over 40% of our clients were single women who wanted to have children with the help of donor sperm.

Read more about your options to fulfil your desire to have children as a single here.

  • Lesbian couples

Since starting Diers Klinik, we have treated a large number of lesbian couples who want to fulfil their desire to have children with IUI. Our founder, Liza Diers, and her partner have also realised their wish to have children this way. Read more about how to pursue your dream of having children as a lesbian couple.

  • Couples with a trans man

More and more trans couples, where the man was born a woman and is therefore unable to father children himself, come to our clinic to fulfil their desire to have children with the help of donor sperm. Jonas and Steffi are one of the couples who had their daughter this way and openly tell their story in our blog.

  • Heterosexual couples

If the man’s sperm quality is reduced, preparing the sperm for IUI treatment may be the method that leads to success. Find out more about IUI insemination with partner sperm here.

What Are the Chances of Having Twins with IUI?

Twins are fascinating, and the occurrence of twins is even more so. Twins are classified as fraternal or identical:

  • Fraternal Twins:

Fraternal twins are also called dizygotic (two-cell) twins. When fraternal twins occur, the mother has produced two egg cells in the cycle in which the successful IUI is performed. During ovulation, these eggs are released and captured by the fallopian tubes. If both eggs are fertilised by their respective sperm, they can both implant and develop in the uterus. This results in the formation of two embryos. The two children each arise from their own egg cell and their own sperm cell.

  • Identical Twins:

Identical twins, as the name suggests, originate from just one egg. The fertilised egg cell divides in the first few days after fertilisation, resulting in 2 embryos formed from a single egg cell and a single sperm cell. Depending on when the egg cell divides, the embryos can implant themselves in the uterus independently or together.

Before we carry out the insemination (IUI), we always conduct an ultrasound examination. If we detect two mature follicles on ultrasound, the chance of twins  occurring is slightly increased. In that case, fraternal twins would result.

As mentioned earlier, the chances of having twins with IUI treatment are still less than 2%. The chances are comparable to trying to conceive naturally with your partner. The numbers are similar because we perform the insemination treatment (IUI) in your natural cycle.

Natural Factors That Increase the Chances of Having Twins

However, some natural factors can increase the chance of twins. These factors also apply to IUI treatment:

  • Age Factor

 The chances of having fraternal twins increase with age. Women older than 35 are more likely to have twins than younger women.

This is related to the hormone FSH, which influences the maturation of the follicles. As FSH levels rise, the tendency to produce more follicles increases, thus raising the chance of releasing more than one egg.

  • Increased BMI

Studies suggest that women with a BMI over 30 have a higher chance of conceiving twins. However, a high BMI itself also increases risks during pregnancy.

  • Family History

The tendency to mature multiple follicles at the time of ovulation, leading to the release of more than 1 egg, is hereditary. If the woman is a twin herself or if there are twins on the mother’s side of the family, the chances of releasing and fertilising two eggs during ovulation are higher, also with IUI.

This Increases the Chances of Twins During IUI

The natural factors mentioned above also impact the chance of having twins with IUI treatment.

However, the chances of twins occurring with IUI are only further increased compared to natural conception if the woman undergoes hormone treatment before ovulation.

Hormone treatment supports follicle maturation in the ovaries and can cause more than 1 follicle to develop. Since hormone treatment affects women differently, it’s crucial to monitor the number of developing follicles.

If 2 or 3 follicles have matured, insemination can be performed, thus increasing the chance of twins. However, if more than 3 follicles have matured, IUI should not be carried out due to the heightened risks for both mother and fetus.

Chances of Having Twins with Fertility Treatment Variants Other Than IUI

Since insemination is typically done without hormone treatment, the chances of having twins are very low with IUI – less than 2%.

Statistically, however, the number of twin births is rising.

In a study from 2021, researchers collected information on rates of twins from 165 countries for the years 2010 to 2015. They compared them with rates for 1980 to 1985. The study found that the global twinning rate increased by a third, from 9.1 to 12.0 twin deliveries per 1000. In other words the world have reached a “Twin Peak”.

The reason for this? Fertility treatment has advanced rapidly over the years. More and more women and couples are realising their dream of having children through advanced and more invasive fertility treatments methods (e.g. IVF and ICSI).

During IVF treatment, the woman is stimulated with hormones to mature many egg cells. These eggs are then surgically removed from the ovaries and artificially inseminated with sperm in the laboratory. This can be done either in vitro (in a glass = IVF) or via ICSI treatment, where a single sperm cell is directly introduced into the egg cell.

Only after the embryo develops in the lab is it transferred to the uterus, where it must implant for pregnancy to occur. If more than 1 embryo is placed in the uterus, the chance of having twins increases.

However, most fertility clinics nowadays usually transfer only 1 embryo, which means that the chance of twins is not particularly high.

Risks and Complications Associated with Twins during IUI Insemination Treatment

A multiple pregnancy is always considered a high-risk pregnancy. This applies both when becoming pregnant naturally and when an IUI treatment is successful. Complications are more common for both the mother and fetus compared to pregnancies with only 1 fetus.

Women pregnant with twins are at a higher risk of early miscarriage than women pregnant with only 1 child. In the case of a twin pregnancy, the risk of pregnancy-induced hypertension (pre-eclampsia) also increases. Also the risk of gestational diabetes is higher in a multiple pregnancy.

Premature births are more frequent in twin pregnancies. This can entail further risks depending on the week of pregnancy reached.

The risk of congenital malformations is 70% higher in twins compared to singletons, and growth retardation is also more common in twins.

A twin pregnancy isn’t inherently risky, and fortunately, it usually progresses without complications. Nonetheless, it’s even more crucial to keep your check-up appointments and undergo more frequent ultrasound checks to ensure proper development of the fetuses if you’re expecting twins.

We wish all future twin parents the best of luck!

Blogpost by Line, Fertility Coordinator

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