Most babies will be born between 37 and 41 weeks. In Australia in 1999, 93.8% of babies were born within this time frame (taking into account inductions and planned Caesareans). The due date will not really be an issue if the woman starts to labour spontaneously around this time.
The calculated due date will become important if:
- The woman starts to labour prematurely (or the caregiver is considering inducing the baby prematurely, because there are complications). The health of the baby, and the chances of the baby surviving, is often estimated by how old the baby is thought to be in utero, or their gestation.
- The woman goes past her 'due date' and decisions need to be made about scheduling an induction.
If the woman's pregnancy is progressing normally, and she goes past the due date, then knowing a day to estimate when she would be due can help with making decisions about induction. Not being sure about your due date may mean an induction being performed too early (a conservative approach is normally adopted, rather than letting the pregnancy go too far overdue).
Research shows that babies born after 42 weeks of pregnancy are at an increased risk of dying, before the mother goes into labour, or during the labour (to around 1 in 10, rather than 1 in 100). This is because the placenta is perceived as having a limited life span, and is more likely to reduce its function after this time. Statistically, about 500 inductions are done to prevent one baby from dying. Babies born after 42 weeks are at an increased risk of becoming distressed during the labour, increasing the woman's chances of needing an emergency Caesarean operation.
On the other hand, induction methods themselves can overstimulate the woman's uterus, causing tonic contractions, sometimes leading to fetal distress. Women who are induced too early (before the due date) may be at risk of having a baby that is not ready to be born and having breathing difficulties. Earlier inductions are also more likely not to be successful, because the woman's cervix is not ready to open, sometimes resulting in a Caesarean birth. Inductions are more likely to be successful if they are left until after 41 weeks. You may wish to read more about inductions in Class 4.
The additional disadvantages of early induction are that the woman's chances of starting labour on her own are virtually eliminated, and for some women induction means changing their planned birthplace (from home or the birth centre) to the delivery suite. Both of these may impact negatively on the woman's satisfaction with her birth experience
Deciding if and when, to induce your labour should be something you feel comfortable with. A very common time to induce is about 10 days after the due date. Most women will start to labour by this time. Some caregivers (or hospitals) prefer to induce on day 7 and others wait until day 14. If your preference is to avoid intervention, you may choose to wait until 14 days (occasionally some women wish to wait longer than this). If you are not comfortable with waiting up to 42 weeks, then you may wish to be induced on day 10 (or day 7, although this may be too early).
NOTE: Be aware that unless it is an emergency situation, routine induction will not be performed on weekends and public holidays. This may affect your decision to be induced earlier, or wait until a little later. The decisions about when to induce, and what methods may be used, will also depend on how ready the woman's body is to start labouring. You can read more in Class 4 - Is my cervix ripe?
Last revised: Monday, 26 November 2012
This article contains general information only and is not intended to replace advice from a qualified health professional.