Chances of Twins with IUI: Here’s What You Need to Know

If you and your partner are thinking about using intrauterine insemination (IUI) to get pregnant, you might be curious about the possibility of having twins. While it's true that the medication used during this fertility treatment can increase your chances, this does not guarantee that you will conceive twins.

To help you better understand how this fertility treatment can increase the odds of having twins (or even triplets), let's take a closer look together.

Does IUI make a twin pregnancy more likely?

On its own, IUI treatment doesn't increase the likelihood of your having twins or triplets. That's because this treatment simply deposits your partner's sperm into your womb using a thin, flexible tube known as a catheter.

Think of it this way, IUI only shortens the distance that the sperm need to swim to reach the egg waiting in the fallopian tubes. So, this fertility treatment doesn't affect the way conception happens or the number of eggs released by the ovaries.

However, during the IUI cycle, it is possible that you may be given ovulation induction medication, such as clomiphene citrate (Clomid), to stimulate multiple ovarian follicle growth. As a result, multiple eggs can be released during ovulation, increasing the likelihood of more than one egg being fertilised and resulting in a multiple pregnancy.

How does the chance of twins differ from IUI compared to IVF?

Assisted reproductive technology (ART), such as IUI or in vitro fertilisation (IVF), can both increase the likelihood of a multiple pregnancy.

With IUI, if only one egg is released during treatment, the likelihood of having twins is the same as natural conception, at around 1 to 2%. However, this chance increases if fertility medications are used during your IUI treatment.

On the other hand, during IVF, your doctor can control the number of embryos transferred to your womb after external fertilisation. With single embryo transfer, your doctor will only transfer one embryo, significantly reducing the chance of a twin pregnancy.

However, if you are over 40 or the quality of the embryos is less likely to result in pregnancy, your doctor might recommend transferring more than one embryo. In these cases, IVF can increase your chances of having a twin conception.

If you are considering ART and have concerns about your risk of multiple pregnancy, schedule a consultation with Thomson Fertility Centre. Our fertility specialist can assess your individual fertility conditions and offer a tailored treatment plan.

What factors increase the chances of twins with IUI?

While IUI itself doesn't increase the chance of twins, the use of ovarian stimulation during the procedure can increase the chance of twin pregnancy. However, there are other factors that can affect your chances of getting pregnant with twins. These include:

• Maternal age:

  • If you are in your 30s or 40s, you will usually have higher oestrogen levels, which naturally stimulate multiple follicles to mature.

  • These hormonal changes mean you are more likely to release more than one egg during ovulation, which increases the likelihood of conceiving twins.

• Family history:

  • If there is a history of fraternal twins (where two different eggs are fertilised) in your family, you may be more likely to have twins due to hyperovulation, which is when your body releases more than one egg during ovulation.

• Previous twin pregnancies:

  • Having experienced a twin pregnancy previously increases your likelihood of conceiving twins again in future pregnancies.

• Weight and height:

  • If you're overweight, you may have a higher chance of conceiving twins naturally due to weight-related hormonal influences.

  • Additionally, taller women are more likely to have twins, possibly due to higher levels of insulin-like growth factor.

Potential risks of multiples pregnancies with IUI

While you may not have a problem carrying twins, you should be aware of some risks that's associated with multiple pregnancy. These risks include:

Side effects of fertility medication

Before IUI, your doctor may prescribe ovulation-stimulation drugs (such as injectable gonadotropin) to help several follicles mature. While these medications are generally safe and tolerable, they can occasionally cause ovarian hyperstimulation syndrome (OHSS), where the ovaries respond more strongly than usual and become enlarged. 

In severe cases, OHSS can lead to complications such as kidney problems, blood clots, and breathing difficulties.

Increased maternal risk

Twin pregnancies naturally place additional strain on the mother's body because she has to nourish two babies, which can lead to:

• An increased risk of caesarean section.

• Anaemia, a condition where there aren't enough healthy red blood cells to carry oxygen around the body.

• Gestational diabetes is a type of diabetes that develops during pregnancy when the body cannot produce enough insulin to manage increased blood sugar levels.

• Gestational hypertension, which is high blood pressure caused by the heart working harder when carrying twins.

• Placental complications, such as abruptio placentae, a condition in which the placenta prematurely separates from the uterine wall.

• Postpartum haemorrhage, which is heavier bleeding after delivery.

Increased foetal risk

Twins typically arrive earlier than single babies, usually around 36 to 37 weeks rather than 40 weeks. This means your little ones may experience premature births, which can result in a lower birth weight. If that's the case, your baby may need to stay in the neonatal intensive care unit (NICU) after delivery to ensure their safety.

Due to the risk of multiple pregnancy in intrauterine insemination, your fertility doctors will monitor your egg growth by using transvaginal ultrasound and may recommend cancelling the IUI procedure if there are more than 3 eggs developing.

For personalised guidance about multiple pregnancy possibilities for your fertility condition, schedule a consultation with our fertility specialists at Thomson Fertility Centre.

How to manage multiple pregnancy risks?

To balance the chances of a successful pregnancy with multiple pregnancy risks, fertility specialists usually aim for no more than two to three mature follicles if you are under 40 and two follicles if you are 40 or older.

Additionally, before undergoing IUI with fertility medication, you should have a thorough discussion with your healthcare provider about the risks and benefits of continuing with IUI based on your follicle count.

FAQ

When does the risk of twins increase during IUI treatment?

IUI on its own does not increase the likelihood of having twins. However, the risk increases when you take ovarian stimulation medications such as Clomid or gonadotropin, as these can stimulate your ovaries to release more than one egg.

What factors affect twin rates with IUI?

How does IUI compare to IVF?

Can the risk of a twin pregnancy be reduced?

Can lifestyle factors influence twin chances with IUI?

No, factors such as diet, rest and exercise don't significantly affect your chances of having twins through IUI. Instead, the most significant influences are fertility medications, the number of mature follicles, age, weight, and family history.

What is the ideal number of follicles for IUI?

Increasing the number of mature follicles from 1 to 5 can improve pregnancy rates, but it also increases the likelihood of having twins. For women under 38, the rate of clinical pregnancies rises from 14.6% with one follicle to 21.9% with five. As such, most doctors aim for 1-3 mature follicles to strike the best balance between success and safety.

The information provided is for general guidance only and should not be considered as medical advice. For a personalised fertility consultation and tailored advice, schedule an appointment with Thomson Fertility Centre today.