Anatomy of pregnancy and birth - pelvis

Your pelvis is located below your abdomen (tummy) and above your thighs.

In females, your pelvis includes your:

• bony pelvis — your hip bones
• pelvic cavity — the space surrounded by your pelvic bones, where your bladder, rectum and reproductive organs are found
• pelvic floor — muscles and ligaments that support your bladder, bowel and uterus
• perineum — the area between the opening of your vagina and your anus

The bones around your pelvis are attached by several ligaments, comprised of tough and flexible tissue. These help your pelvis to function.

Your pelvis has many roles, including:

• holding your body upright so you can stand, walk and run
• holding your urinary and reproductive organs in place
• helping control your bladder and bowels

The female pelvis is wider than the male pelvis. This is because it is designed to support pregnancy and childbirth.

During pregnancy, the hormone relaxin relaxes your pelvic joints and ligaments. This helps your pelvis to support and accommodate your growing baby during pregnancy. It also makes childbirth easier for both you and your baby.

While pregnancy hormones adjust your pelvis to support your pregnancy, they can also cause instability in your pelvic area, lower back pain and pelvic pain (also known as pelvic girdle pain).

Other causes of pelvic girdle pain can include:

• your growing baby and uterus putting more pressure on your pelvis as your pregnancy progresses
• changes to your posture
• urinary tract infection
• preterm labour

Certain activities may increase your pelvic girdle pain, such as:

• walking a long distance
• walking quickly, running or jumping
• getting in and out of your car or bed
• lying flat or rolling in bed
• going up or down stairs
• deep squatting or lunging
• standing on one leg

Your pain may be mild, or severe to the extent that you cannot move.

Here are some tips to help you manage your pelvic girdle pain:

• Sleep on your side with a pillow between your legs.
• Get in and out of bed with your knees together.
• Apply heat to the painful areas.
• Wear low-heeled, supportive shoes.
• Avoid standing on one leg — sit down to get dressed and climb stairs one at a time.
• Walk shorter distances. Avoid standing or walking for long periods of time.
• Be careful with movements that stretch your hip, such as getting in and out of cars, sitting on low stools and squatting.

You may also find it helpful to seek advice from a physiotherapist. They can assess you and give you exercises and posture advice.

Although rare, there are other conditions that can affect your pelvis during pregnancy and childbirth. See your doctor if you have ongoing pelvic pain or back pain during pregnancy.

To find a physiotherapist or maternal, child and family health service near you, use the Pregnancy Birth and Baby Service Finder tool.

During a vaginal birth, your cervix becomes fully dilated. Your baby is likely to be positioned with their head down and facing your back. This position helps them move down through your pelvis and birth canal to your vaginal opening.

Your pelvic floor muscles may be stretched and strained. Especially if you have had a long labour or a large baby, your pelvic floor muscles will become weakened.

Read more about how to take advantage of the structure and function of your pelvis by adapting your position to assist in childbirth.

Baby in breech position

A baby who lies bottom or feet down in your pelvis during late pregnancy is said to be in a 'breech' position. This may increase your chances of having a complicated vaginal birth.

If late in your pregnancy your baby is still in the breech position, your obstetrician can perform a technique called external cephalic version (ECV) to help your baby turn.

Talk to your doctor or midwife about your options if your baby is in the breech position. If it is not possible to turn your baby, your doctor may recommend a caesarean section.

• Queensland Health has practical information outlining what you should know about your pelvic floor: pre-pregnancy, during pregnancy and after giving birth.
• The Royal Australian and New Zealand College of Obstetricians and Gynaecologists has a helpful resource answering some common questions people have in pregnancy.
• Read about self-care for expecting and new parents at PANDA.
• Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available from 7 am to midnight (AET), 7 days a week (including public holidays).

Other languages

• The Multicultural Centre for Women's Health has a catalogue of health resources for females, available in more than 70 languages.
• Visit the Healthy Horizons website to find health information for people born outside Australia.

Aboriginal and/or Torres Strait Islander peoples

• 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.

Sexually and gender-diverse families

• PANDA provides inclusive and appropriate support for LGBTIQA+ expecting and new parents.