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:
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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. |
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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.