When does labor need to be induced?
If a pregnant woman is a few days overdue but there’s no sign of any problems, there’s little risk for the unborn child. But if the baby is more than one week late, inducing labor will lower the risk of complications.
Most babies are born around the estimated due date, usually within two weeks before or afterwards. Pregnancy is considered to be “full-term” at 40 weeks (or 280 days). A pregnancy that continues for longer than 42 weeks is called a post-term, prolonged or overdue pregnancy. If the mother and baby are both doing well, being up to one week “late” isn’t associated with any particular risks for either of them.
But after that, the likelihood of the mother or child developing health problems gradually increases. Labor can then be induced quickly, or the baby can be delivered by an operation known as a Cesarean section. This does not happen a lot, though, because most overdue women go into labor naturally before further steps become necessary.
Advantages and disadvantages of inducing labor
The disadvantages of being overdue usually affect the baby rather than the mother. The main risk is that the placenta might stop providing the baby with everything he or she needs. The risk of infections in the womb and unexpected complications during childbirth increases too. Although being overdue is generally associated with fewer risks for the pregnant woman, childbirth can be more difficult if the child is too big.
But if a woman doesn’t go into labor – naturally or induced – long after the due date, she or her baby might suddenly develop such serious health problems that an emergency Cesarean section might be necessary.
It is difficult to say at what point a woman has been pregnant for too long. In most cases, medical examinations don’t detect any problems even days after the estimated due date. To lower the risk of complications, though, it is common to induce labor after a certain amount of time has passed, even if the mother and baby are still doing well.
It makes sense to induce labor at the point when the benefits to the mother and baby outweigh the potential risks associated with inducing labor.
Inducing labor after 41 completed weeks has more advantages than disadvantages
Researchers from the Cochrane Collaboration – an international network of researchers – wanted to find out at what point in pregnancy it makes sense to induce labor. To do so, they looked for studies in which pregnant women had agreed to either be induced in a particular week, or to wait and only be induced if there were any problems. The women were randomly assigned to one of the two groups. All of the women in the studies had a low risk of complications during birth. Women with known health problems didn’t take part in the studies.
The women who weren’t induced in a certain week had regular check-ups, usually twice a week. This allowed their doctors to see whether there were any problems that would make it necessary to induce labor or deliver the baby by Cesarean section after all. The check-ups included things like monitoring the baby’s heart electronically and measuring the amount of amniotic fluid surrounding the baby in the womb.
The researchers found a total of 22 studies including about 9,400 women. This is what was found: If a baby still hasn’t been born more than one week after the due date, inducing labor can lower the risk of him or her dying.
Ten studies involving about 6,000 women looked into whether inducing birth one week after the due date can reduce the risk of the baby dying. The main finding was:
- Without inducing: When labor wasn’t induced after a certain amount of time, about 3 out of 1,000 overdue babies died.
- After inducing: When labor was induced after 41 completed weeks of pregnancy, fewer than 1 out of 1,000 overdue babies died.
In other words: The research showed that inducing labor after 41 full weeks of pregnancy prevented 2 out of 1,000 babies from dying during birth or shortly afterwards.
Inducing labor after this amount of time was also found to lower the risk of other problems such as meconium aspiration (breathing in meconium). Meconium is the medical term for the baby’s bowel contents which are released into the amniotic fluid during labor. If the baby becomes very distressed during labor, he or she might breathe in meconium, which can then get into his or her lungs. Meconium aspiration can cause serious breathing problems. The studies showed the following:
- Without inducing: When labor wasn’t induced after a certain amount of time, meconium aspiration occurred in about 11 out of 1,000 babies.
- After inducing: When labor was induced, about 7 out of 1,000 babies had this problem.
Being overdue often increases the likelihood of needing a Cesarean section. This operation is associated with risks such as bleeding, infections and poor wound healing. The studies on inducing labor show that women are somewhat less likely to need a Cesarean section if labor is induced after 41 completed weeks:
- Without inducing: When labor wasn’t induced, about 180 out of 1,000 women had a Cesarean section.
- After inducing: When labor was induced, about 160 out of 1,000 women had a Cesarean section.
At the end of the day, the decision of whether to induce labor – and, if so, when to induce it – is made on an individual basis. It will mainly depend on the risk of complications during childbirth. This risk is influenced by various things, including how overdue the pregnancy is, the mother’s age and how big her baby is.
Gülmezoglu AM, Crowther CA, Middleton P, Heatley E. Induction of labour for improving birth outcomes for women at or beyond term. Cochrane Database Syst Rev 2012; (6): CD004945.
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