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Uterine differences

Key facts

  • The uterus (womb) is part of the female reproductive system and is where a baby grows during pregnancy.
  • The uterus is a hollow organ and is usually around the size and shape of an upside-down pear.
  • Some people are born with a uterus that has a different anatomical (physical) structure or shape.
  • In some people, uterine differences may cause painful periods or pain during sex.
  • Some people with uterine differences may find it hard to fall pregnant, experience recurrent miscarriages or premature birth.

What is the uterus?

The uterus (womb) is an organ of the female reproductive system (Opens in new tab). It’s where a baby grows and develops during pregnancy. 

Your uterus is a hollow organ and is around the size and shape of an upside-down pear. It sits low down in your abdomen (tummy).

Your uterus is connected to your vagina by your cervix. On both sides of your uterus are your ovaries, which store and release eggs. Fallopian tubes connect your ovaries to your uterus.

The uterus has 2 layers. The myometrium is the outer layer of muscle tissue. The endometrium is the inner layer or lining.

How do uterine differences (differences of the uterus) form?

Some people have a uterus with a different anatomical (physical) structure or shape. If your uterus has a different shape, it was likely formed before you were born.

When a female baby develops, their uterus grows as 2 separate halves from 2 tubular structures called 'Mullerian ducts'. These ducts fuse (join) together before the baby is born and create the uterus.

Sometimes this doesn’t happen as expected causing differences in the shape and structure of the uterus. Very rarely, a uterus may not form at all.

What are uterine differences and will I be able to have a baby?

Many people with different uterus shapes can have a baby. However, certain uterine differences can make it harder to get pregnant. Other types can make you more likely to have a miscarriage or give birth prematurely (early).

Arcuate uterus

An arcuate uterus looks mostly like a normal uterus but has a small dip at the top of the womb. It doesn’t affect your fertility, but it does increase the risk of a later miscarriage.

You might also need to have a caesarean if your baby is not in the correct position.

The arcuate uterus looks very similar to a normal uterus but has a small dip at the top of the womb.

Illustration of an arcuate uterus compared to a normal uterus.

Septate uterus

A septate uterus has a wall of muscle that comes down the centre of the uterus and splits it into 2 areas. If the wall only comes down part way, it is known as a subseptate uterus. If it comes down the whole way, it is called a septate uterus.

This uterine difference can affect your fertility. It can also increase the risk of early miscarriage or having your baby prematurely.

A septate womb has a wall of muscle that comes down the centre of the uterus and splits the uterus into two areas.

Illustration of a septate uterus compared to a normal uterus.

Bicornuate uterus

A bicornuate uterus has a deep indentation at the top of the uterus. It doesn’t lower your chance of falling pregnant. However, it increases your risk of early miscarriage or having your baby prematurely.

A bicornuate uterus has a deep indentation at the top of the uterus.

Illustration of a bicornuate uterus compared to a normal uterus.

Didelphic uterus

If your uterus is didelphic (uterus didelphys), it means that your uterus is split in 2. Each side of the uterus has its own cavity (internal area).

There is an increased chance of having a premature birth if your uterus is didelphic.

A didelphic uterus is split into two separate halves, each with its own uterus (womb) and cervix. Both cervixes lead into one vagina.

Illustration of a didelphic uterus compared to a normal uterus.

Unicornuate uterus

With a unicornuate uterus, the womb is half the usual size. It occurs because half of the uterus didn’t develop as expected.

This uterine difference is rare. Having a unicornuate uterus does not affect your fertility, but it increases the risk of early miscarriage or having your baby prematurely.

A unicornuate uterus is about half the usual size. It has one narrow cavity that curves to one side, with one fallopian tube and one ovary.

Illustration of a unicornuate uterus compared to a normal uterus.

How will I know if I have a different uterus?

Many people with uterine differences don’t know about it. You may learn that you have a different uterus when your doctor is investigating (checking for causes of problems) such as: 

If your doctor thinks that you have a different uterus, you may be referred for a transvaginal ultrasound (Opens in new tab) (an ultrasound done through the vagina) to learn more.

Your doctor might also suggest that you have an MRI (Opens in new tab) or other scans so that they can better understand the anatomy (shape) of your uterus.

Sometimes, uterine differences are linked with anatomical differences of the kidneys (Opens in new tab) and bladder (Opens in new tab). Your doctor may also suggest scans to see the structure of your bladder and kidneys.

How are uterine differences managed during pregnancy?

If you have a uterine difference, your pregnancy may be managed by an obstetrician (a specialist in pregnancy and childbirth).

There are no specific medicines or procedures that completely prevent premature birth in people with uterine differences. However, your doctor or specialist may be able to recommend ways to manage your case.

Are there risks to me and my baby if I have a uterine difference?

Often, uterine abnormalities don't cause any symptoms or problems.

Sometimes, people with uterine differences have painful periods (Opens in new tab) or pain during sex (Opens in new tab). Others may have difficulties getting pregnant or recurrent miscarriages.

If you are pregnant and have uterine differences, you may have a higher risk of certain complications during pregnancy. These complications can be:

People with uterine differences are also more likely to give birth early.

Resources and support

You can get help and information online or over the phone.

Speak to a maternal child health nurse

Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 (Opens in new tab) or video call. Available 7am to midnight (AET), 7 days a week.

Last reviewed: March 2026

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