A new European study has found that continuing a pregnancy past term, 37 weeks, appears to increase the risk of stillbirth, a finding which researchers hope will help women make decisions with regards to labour induction.
Led by Queen Mary University of London, UK, the new study looked at data from 13 separate studies carried out in the UK, US, Denmark, and Norway, which included a total of 15,124,027 pregnancies, 17,830 stillbirths and 2,348 newborn deaths.
The findings, published in the journal PLOS Medicine, showed that with every week that pregnancy continued past 37 weeks, the risk of stillbirth increased. In addition, the team also found a small but significantly increased risk of stillbirth in mothers who continued their pregnancy to 41 weeks’ gestation, which is when women are routinely offered labour induction, compared to women who delivered their baby at 40 weeks.
However, the researchers also noted that women who carry to 41 weeks should not be alarmed, adding that the increased risk of stillbirth is low, equivalent to one additional stillbirth for every 1,449 pregnancies, compared to delivering at 40 weeks.
“While there is an additional risk of stillbirth at 41 weeks, compared to 40 weeks, it is small. Women who prefer not to have medical interventions such as induction of labour may, therefore, acknowledge this small additional risk, and choose to wait until 41 weeks so that they have more time to go into labour naturally,” said lead researcher Professor Shakila Thangaratinam. “Meanwhile, other women may prefer to have discussions with their healthcare providers on induction after 40 weeks. So this is all about helping women make informed decisions on the timing of delivery.”
The results also showed that when compared to White women, Black women at term were also 1.5 to 2 times more likely to suffer stillbirth no matter how far along with their pregnancy, with Thangaratinam adding that “Healthcare professionals need to take these added risks into account when developing care plans for these women.”
Despite the increased risk of stillbirth, delivery between 38 and 41 weeks gestation did not appear to increase the risk of neonatal death, when an infant dies during the first 28 days of life, although the risk increased by 87 percent for deliveries at 42 weeks’ gestation compared to 41 weeks.
Professor Thangaratinam concluded that “This is the largest study of its kind, and finally provides precise estimates of potential risks of stillbirth. Now that we understand the extent to which stillbirth risks increase with each week of pregnancy, we should be incorporating this information in all discussions around delivery plans in pregnant women at term.”