Pregnancy beyond the term: what are the risks for the baby?
The average pregnancy lasts 40 weeks, plus or minus week. But can those extra weeks put our baby’s life at risk?
What are the risks of stillbirth (death in utero, or MEF, is defined as fetal death after the 22nd week of pregnancy) and neonatal death in case of gestation beyond the expected term?
The answer would come from a systematic review and meta-analysis of cohort studies done on 15 million pregnancies.
This is a considerable number of analyzed data, which have made it possible to reach a conclusion that cannot be underestimated: the risk of stillbirth increases for low-risk pregnancies that continue beyond 40 weeks.
According to the researchers, the risk of stillbirth increased steadily from 0.11 per 1,000 pregnancies at 37 weeks (95% CI 0.07-0.15) to 3.18 per 1,000 at 42 weeks (95% CI 1.84-4 ,35).
According to the guidelines for physiological pregnancy , maternal, fetal and neonatal risks increase beyond 41 weeks of gestational age and induction to childbirth is often practiced after this date.
According to the researchers, however, 1 in 3 deaths still occurs before 41 weeks. And mothers and caregivers need to be aware of these numbers which cannot be overlooked.
Endouterine or neonatal death is one of the most difficult traumas to face and overcome for any mother and father.
Study data
To calculate the week-to-week increased risk of fetal and newborn death so that they could provide risk estimates for expecting couples and caregivers, the researchers included 13 studies in their meta-analysis, most of which came from the US and the UK. These studies analyzed more than 15 million pregnancies that occurred from 1990 to 2015, reporting nearly 18,000 stillbirths and approximately 2,400 neonatal deaths.
All studies considered low-risk pregnancies and excluded pregnancies with congenital fetal malformations and twin pregnancies.
The researchers highlighted a higher risk of stillbirth in prolonged pregnancies, while the risk of neonatal death remained unchanged for births starting from 38 and up to 41 weeks of gestation. At 42 weeks, the risks change considerably as you can see from the chart below.
It has also been shown that compared to white women, full-term African American women are 1.5 to 2 times more likely to experience perinatal death regardless of gestational age.
According to experts, this analysis is much more extensive than previous studies and reflects current knowledge about the risks in case of prolonged pregnancies.
Once 40 weeks of pregnancy is reached, if the dating is correct (dating is a datum that cannot be underestimated), the outcome of this study should be taken into consideration when deciding when to induce delivery. In fact, the data obtained must support informed decision-making between patients and medical staff when deciding whether to continue up to 41 or induce from 40 weeks completed.
” Our findings, ” said the study authors, ” are intended to enable women to make informed decisions about when to give birth .”
Lead researcher on the study Shakila Thangaratinam of Queen Mary University of London added: ‘ Although there is an additional risk of stillbirth at 41 weeks, compared with 40 weeks, this risk is small. Women who prefer not to have medical interventions such as labor induction can therefore recognize this small additional risk but choose to wait until 41 weeks in order to give labor more time to start naturally. In the meantime, other women could choose, in agreement with the doctors, to be induced by the 40 weeks. So it’s all about helping women make informed decisions about when to give birth . ”
Kathryn Barlow is an OB/GYN doctor, which is the medical specialty that deals with the care of women's reproductive health, including pregnancy and childbirth.
Obstetricians provide care to women during pregnancy, labor, and delivery, while gynecologists focus on the health of the female reproductive system, including the ovaries, uterus, vagina, and breasts. OB/GYN doctors are trained to provide medical and surgical care for a wide range of conditions related to women's reproductive health.