There is a small benefit of inducing labour over a “wait and see” approach for late term pregnancies, according to researchers in Holland.
They found inducing labour at 41 weeks of pregnancy lead to a small reduction in birth complications compared with expectant management until 42 weeks in low risk women.
“The results of our study should be used to inform women approaching a gestational age of 41 weeks”
However, the absolute risk of serious problems was low in both groups, suggesting the results were not sufficiently conclusive to change current practice.
Late term pregnancy – at or beyond 42 weeks – affects about 15% of women and is associated with adverse perinatal outcomes, including death.
The authors of the new research, published in the British Medical Journal, said some previous studies had suggested that inducing labour from 41 weeks onwards improved outcomes.
They noted that these studies were all different regarding their measures, protocols and time frames of comparison and, therefore, the results needed to be interpreted with caution.
But they highlighted that, despite such concerns, induction at 41 weeks was now an accepted policy in many countries throughout the world.
As a result, the researchers at the University of Amsterdam set out to compare induction of labour at 41 weeks with expectant management until 42 weeks in low risk pregnancies.
Their trial included 1,800 women – mainly white and younger than 35 years – with an uncomplicated pregnancy recruited from 123 midwifery practices and 45 hospitals in the Netherlands.
Women were randomised to either induction at 41 weeks or expectant management until 42 weeks with subsequent induction if necessary.
“The remaining data suggest little to choose between the two management options”
Adverse perinatal outcomes were assessed using a combined measure of newborn health – including perinatal death, Apgar score of less than 7 five minutes after birth, and admission to intensive care.
Other outcomes that were assessed included the type of delivery and the mother’s health just after giving birth.
Overall, 1.7% in the induction group had an adverse perinatal outcome compared with 3.1% in the expectant management group – an absolute risk difference of 1.4% in favour of the induction group.
In addition, 1.2% of infants in the induction group and 2.6% in the expectant management group had an Apgar score of less than seven out of 10 at five minutes.
No infants in the induction group and 0.3% in the expectant management group had an Apgar score of less than four out of 10 at five minutes.
One foetal death – equivalent to 0.1% – occurred in the induction group and two (0.2%) in the expectant management group. No neonatal deaths occurred.
Meanwhile, 0.3% of infants in the induction group versus 0.9% in the expectant management group were admitted to an intensive care baby unit.
No significant differences in the mother’s health or in caesarean section rates were found between groups.
The researchers said induction of labour at 41 weeks resulted in less overall adverse perinatal outcome than a policy of expectant management until 42 weeks, although the absolute risk of severe adverse outcome was low in both groups.
They said: “As with every intervention in the natural birth process, the decision to induce labour must be made with caution, as the expected benefits should outweigh possible adverse effects for both mother and child.
“The results of our study should be used to inform women approaching a gestational age of 41 weeks, so they can weigh the respective outcomes and decide whether to be induced at 41 weeks or to continue pregnancy until 42 weeks,” they added.
Professor Sara Kenyon and colleagues, from the University of Birmingham, welcomed the new trial, but warned that the results were “not sufficiently conclusive to change current practice”.
If the Apgar scores were excluded, “the remaining data suggest little to choose between the two management options”, they highlighted in a linked editorial also published in the BMJ.
In addition, they warned that increasing induction rates – 35% of women giving birth for the first time are currently induced in the UK – “may also impact negatively on women’s birth experience”.