Anatomy of pregnancy and birth - abdominal muscles

Your abdominal muscles are the muscles in the front of your body, between your ribs and pelvis.

You have several pairs of abdominal muscles. They are called:

• external oblique muscles
• internal oblique muscles
• rectus abdominis muscles
• transversus abdominis muscles

Your abdominal muscles are designed to:

• support your spine, so you can stand upright
• support your trunk and pelvis
• protect the organs in your abdomen
• help you breathe, sneeze, cough, vomit and open your bowels
• help you move your spine so you can bend and twist

During pregnancy, your growing baby and uterus (womb) stretch and weaken your abdominal muscles. This can make your abdominal muscles less effective at supporting your body and helping you move.

Strengthening your abdominal muscles during and after pregnancy helps these muscles work properly.

Abdominal separation

There is always a small gap between your abdominal muscles. Sometimes during pregnancy, the gap grows when the two bands of the rectus abdominis muscle (that normally meet in the middle of the abdomen) separate. This is called 'diastasis recti abdominus' or abdominal separation.

You can develop abdominal separation because of:

• stretching and weakening of your muscles as your baby and uterus grow
• pregnancy hormones that soften your ligaments and abdominal muscles
• weight gain during pregnancy

Abdominal separation may cause pain in your lower back. It might become hard to lift things or do other physical activities.

If you have abdominal muscle separation, your doctor or midwife will usually refer you to a specialist physiotherapist. They will recommend a special exercise program. Occasionally, surgery is recommended for this condition.

If you think you may have abdominal separation, see your doctor, midwife or maternal health service.

You can strengthen your abdominal muscles by:

• doing special strengthening exercises during and after your pregnancy that will help your muscles return to their original shape
• wearing an abdominal support band or firm compression underwear

A safe way to work your abdominal muscles and improve core strength is by drawing in the muscles without moving your spine. To do this exercise try to imagine sucking your belly button in towards your spine.

Safety tip

Sit-ups and crunches are not recommended during pregnancy. This is for 2 reasons:

1. Your stretched abdominal muscles do not work in the same way as when you aren't pregnant. This makes sit-ups less effective during pregnancy.
2. Sit-ups and crunches are usually done while lying on your back. This position isn't recommended during pregnancy. It can cause dizziness because the weight of your baby rests on your major blood vessels.

Talk to your doctor, midwife or physiotherapist about how to build and maintain your core strength.

• The Royal Women's Hospital has an informative factsheet about exercise during pregnancy as part of a healthy lifestyle.
• Learn how to manage diastasis recti.
• Read about self-care for expecting and new parents at PANDA.
• The Pregnancy, Birth and Baby video call service allows you to speak face-to-face with a maternal child health nurse. Video call is a free service and is available from 7am to midnight (AET), 7 days a week (including public holidays).

Do you prefer to read in languages other than English?

The Multicultural Centre for Women's Health has a catalogue of health resources, available in more than 70 community languages.

Looking for information for Aboriginal and/or Torres Strait Islander people?

You can find out more about Aboriginal and/or Torres Strait Islander pregnancy health on Stronger Bubba Born or watch the How to Have a Safer Pregnancy video.

Find an Aboriginal Community Controlled Health Organisation (ACCHO) or Affiliate near you.

Looking for information for sexually and gender-diverse families?

The Centre of Perinatal Excellence (COPE) has resources and tips for LGBTIQ+ parents and rainbow families.