Sometimes labour can be induced (started artificially) if your baby is overdue or there is any sort of risk to you or your baby’s health.
Calculating due dates
Your due date is anywhere between 37 and 42 weeks gestation or 266 days from the day of conception, or 280 days or 40 weeks from the first day of your last period. This is based on a 28 day cycle and conception 14 days after the first day of your period.
Obviously accurate dating is really important and it is said that the most accurate date is that of the first ultra sound.
What happens if I go over my due date?
If you have a normal, uncomplicated pregnancy, most caregivers will discuss inducing labour somewhere between 41 and 42 weeks.
Caregivers will closely monitor your pregnancy and baby at this time, and you will see your caregiver on a weekly basis from 36 weeks gestation. Once you have gone over your due date, you may have regular CTG’s (cardiotocography's), which is where the baby’s heart rate is monitored.
In high-risk pregnancies, a biophysical profile may also be performed via ultrasound, which measures the amniotic fluid around the baby, heart rate, movement, breathing and muscle tone.
Approximately one quarter of women have an induction of labour.
The most common reasons for induction are:
- Concerns for your health, such as diabetes or high blood pressure.
- Concerns for baby’s health.
- Your pregnancy has gone more than 10 to 12 days beyond the due date and there is a risk that the placenta can no longer sustain baby’s life.
- Your water breaks (amniotic sac that holds your baby), but contractions don’t begin.
How will my labour be induced?
You will require a vaginal examination by your caregiver to see what your cervix is up to and what will be the best method of induction for you. Based upon that examination one (or a combination) of the following methods will be recommended:
Prostaglandin is a gel that is inserted into the area between the posterior wall of the vagina and the cervix (we call it the posterior fornix) and is used to stimulate the cervix to soften, ripen and begin to open.
An ARM (artificial rupture of the membranes) is performed by your midwife or obstetrician and using a small hook (Amnihook) or forceps (Alligator forceps) a tear is made in the amniotic sac, thereby releasing the amniotic fluid around your baby. Sometimes this enough to get things ‘moving’ so to speak but if it does not then the use of an oxytocin infusion will be required.
Cervical ripening balloon catheter
A cervical ripening balloon catheter is used when prostaglandin gel is not appropriate. A catheter is inserted through the vagina into the cervix whereby the balloon is filled with normal saline where it will apply pressure to the cervix, to encourage softening and dilatation.
Oxytocin (syntocinon infusion)
An oxytocin infusion or a syntocinon infusion as it is called in Australia, is used when contractions don’t begin on their own despite using the above methods. Oxytocin is a naturally occurring hormone that causes the uterus to contract. Syntocinon is a synthetic version of it. The membranes must be ruptured prior to the commencement of an oxytocin infusion and CTG monitoring will occur throughout to make sure the baby is doing well.