What is the uterus?

The uterus (womb) is an organ of the female reproductive system. It is where a baby grows and develops during pregnancy. It 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 the vagina by the 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 is made up of 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 most likely formed before you were born, when you were still a fetus.

When a female baby develops, a 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 process doesn’t occur as expected causing differences in the shape and structure of the uterus or 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 uteruses are able to 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).

Bicornuate

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

Unicornuate

A unicornuate uterus means that the womb is half the usual size and occurs because half of the uterus didn’t develop as expected. This uterine difference is rare. Having an unicornuate uterus has no effect on your fertility, but it does increase the risk of early miscarriage or having your baby prematurely.

Didelphic

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.

Arcuate

The arcuate uterus looks very similar to 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.

Septate

A septate womb has a wall of muscle that comes down the centre of the uterus and splits the uterus into 2 areas. If the wall only comes down part way, it is referred to as a subseptate uterus. If the muscular wall comes down the whole way, it is called a septate uterus. It can affect your fertility, and it also increases the risk of early miscarriage or having your baby prematurely.

How will I know if I have a different uterus?

Many people don’t know that they have a different uterus. You may learn that you have a different uterus if your doctor is checking for problems, including recurrent miscarriage, difficulties becoming pregnant, problems with your menstrual cycle or pain during sex.

If your doctor suspects that you have a different uterus, you may be referred for a transvaginal ultrasound (an ultrasound done through the vagina). In some cases, your doctor may suggest that you have an MRI or other scans so that they can better understand the anatomy of your uterus.

Some uterine differences are linked with anatomical differences of the kidneys and bladder. Depending on what uterine difference you have, 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 and followed up by an obstetrician. Unfortunately, there are no specific medicines or procedures that are guaranteed to prevent premature birth in people with uterine differences. However, each person is different, and your doctor may have recommendations specific to your case.

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

If you have a uterine difference, it can impact on your health and pregnancy in different ways. Often, uterine abnormalities don't cause any symptoms or problems. Sometimes, people with uterine differences have painful periods or pain during sex. 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 may include fetal growth restriction (where the baby doesn’t grow as much as expected inside the womb) pre-eclampsia, and fetal malpresentation (difficult positioning of the baby for birth). People with uterine differences are also more likely to give birth early.

Who can I talk to for advice and support?

Talk to your healthcare team for more information. You can also get help and information from:

• Perinatal Anxiety & Depression Australia (PANDA) — call 1300 726 306 to speak with a counsellor (Mon to Fri, 9am to 7.30pm AEST)
• ForWhen — 1300 24 23 22 (Monday to Friday, 9.00am to 4.30pm)
• Gidget Foundation — online and telehealth support — 1300 22 4636
• Beyond Blue — 1300 22 4636