When is pregnancy considered to be overdue?

Pregnancy normally lasts about 40 weeks from the first day of your last period. You reach full term at 37 weeks. If your labour doesn’t start by the time you reach 42 weeks, you are overdue. This is also called ‘postdates’ or prolonged pregnancy.

You can calculate your due date by using this due date calculator. However, every baby is different and there is a range in what is considered normal.

In Australia, most babies are born at term, between 37 and 41 weeks. About 4 in 1000 babies are born at 42 weeks or beyond. However, it’s estimated that about 1 to 2 in every 20 pregnancies would go overdue without medical help.

What causes pregnancy to go overdue?

It is not clear why going overdue happens sometimes. Your pregnancy is more likely to go overdue if:

• you are living with obesity
• you have never given birth before
• you’re over the age of 30
• your baby is male
• you've gone overdue before
• going overdue runs in your family

Complications of being overdue

If your pregnancy goes overdue, there is a risk that the placenta won’t function well enough to supply your baby with oxygen and nutrients. The risk of stillbirth or neonatal death gets higher the longer you go overdue. However, the risk is still low — in Australia, out of every 1000 overdue babies, 2 to 3 die before or soon after birth.

If your pregnancy is overdue, your baby is also at higher risk of:

• not getting enough oxygen or blood flow
• meconium aspiration, which can cause breathing problems
• having a large birth weight
• seizures
• injury during birth
• serious infections

You are also at higher risk of:

• a long labour or difficult birth
• postpartum haemorrhage
• a 3rd or 4th degree perineal tear
• an infection in your uterus

How is my overdue pregnancy managed?

Your midwife or doctor may offer you a ‘membrane sweep‘ at about 40 weeks to see if this will trigger labour. This involves having a vaginal examination where your midwife or doctor will sweep their finger around the inside of your cervix. This stimulates your cervix to produce hormones that may trigger natural labour. You don’t have to have this procedure — it’s your choice, and you can discuss it with your midwife or doctor.

If your labour doesn’t start naturally after this, your midwife or doctor will suggest a date to have your labour induced. This is when your doctor or midwife uses medicines or other techniques to get your labour to start. If your pregnancy is low risk, induction is usually planned to take place in the first few days after you reach 41 weeks.

Induction is planned in advance, so you’ll be able to discuss the advantages and disadvantages with your doctor or midwife and find out why they think your labour should be induced. It’s your choice whether to have your labour induced or not.

If you reach 42 weeks, you will be advised to give birth in hospital rather than at a birthing centre or at home.

What tests will I need to have if I’m overdue?

Your midwife or doctor will check that both you and your baby are healthy by giving you an ultrasound scan and monitoring your baby’s heartbeat with a cardiotocograph (CTG). It’s recommended to do this twice a week from 41 weeks onwards.

If tests show that your baby’s health is at risk, your doctor or midwife will recommend an induction. If tests show that your baby is well and your health is good, you might choose to wait and see whether labour starts naturally.

If your pregnancy lasts longer than 42 weeks and you decide not to have your labour induced, you will probably be offered monitoring more often.

Keep in mind that these tests only tell you how your baby is at that moment. They can’t predict whether your baby’s health might change.

When should I see my doctor or midwife?

If your pregnancy is overdue, it’s very important to pay attention to your baby’s movements. Let your doctor or midwife know straight away if you notice any changes in your baby’s movements. This could mean that the movements suddenly speed up, slow down or stop altogether.

What can I do to prevent going overdue?

Having a membrane sweep (also known as a stretch and sweep) can help bring on labour.

There is no evidence that acupuncture, homeopathy, hot baths, herbal treatments or sexual intercourse can bring on labour if your baby is overdue.

Resources and support

If you have any questions or concerns about going overdue, talk to your midwife or doctor.