Study: Longer Pregnancies Give Rise To The Risk of Infant Deaths
A recent study suggests that with every week that a pregnancy continues past term (37 weeks), the risk of stillbirth and newborn death increases.
Women who carry their pregnancies past full-term increase the risk of stillbirths and newborn deaths. This is over mothers who deliver by 37 weeks’ gestation, a recent study suggests. Doctors have long understood the risk of complications when a pregnancy continues past a woman’s due date. But it was unclear how much the risk of stillbirths or newborn deaths increases with each additional week beyond full term.
Researchers Determine The Size Of Risk Of Stillbirths And Newborn Deaths
To assess the rise in risk, researchers examined data from 13 previously published studies. They included a total of 15 million pregnancies and 17,830 stillbirths. Overall, pregnancies that continued 41 weeks or longer had the greatest risk of stillbirths and newborn deaths within the first 28 days of life.
From weeks 40 to 41, the risk of stillbirths increased 64% compared with delivery at 37 weeks’ gestation. The study found that from weeks 41 to 42, the risk of neonatal deaths climbed 87%.
“It is thought that the placental function slows down as pregnancy continues and beyond the due date,” said Shakila Thangaratinam, senior author of the study and a researcher at Queen Mary University of London.
This seems to play a role in the stillbirths and poor outcomes after delivery.
At 37 weeks, the risk of stillbirth was roughly 1 for every 10,000 pregnancies, the study found. This risk steadily rose, reaching roughly 32 stillbirths for every 10,000 pregnancies by 42 weeks. For neonatal deaths, the risk held steady from 38 to 41 weeks and then started climbing.
“Full-term” pregnancy was generally 40 weeks from the first day of a woman’s last period. But these final weeks are so important to infant development. So in 2013, the American College of Obstetricians and Gynecologists put forward more precise definitions. “Full-term” is from the start of week 39 through the end of week 41 of gestation. “Early term” is week 37 through the end of week 38, and the late-term is from week 42 and beyond.
When Is The Ideal Time To Induce Labour In Full Term Pregnancies?
The World Health Organization recommends labor induction at 42 weeks. Allowing pregnancies to continue means an increased risk of death and complications for both mothers and babies. But previous research on the difference in outcomes between 41 and 42 weeks has been mixed. And guidelines in many countries differ on which of these approaches is best.
“Fundamentally, we know that the risk increases slightly with each subsequent week and rises even faster after 41 weeks,” said Dr. Aaron Caughey chair of Obstetrics and Gynecology. He is also Associate Dean for Women’s Health Research and Policy at Oregon Health & Science University in Portland.
“But, the issue at any given week is the tradeoffs between induction and expectant waiting a week or more.” Mr. Caughey, who wasn’t involved in the study, said. For women without any pregnancy complications, it’s best to wait until 39 weeks to consider induction or a surgical delivery.
The Study Requires Additional Research
The analysis wasn’t designed to determine why the risks increase with longer gestation. And the researchers lacked data on individual women’s circumstances. So they couldn’t say whether specific health issues or complications might have contributed to the risk of stillbirths or newborn deaths.
Even then, the results underscore that pregnancy for many women can and should last beyond 37 weeks.
It’s ideal if women reach their full gestation of 41 weeks, as this allows the baby to fully develop. Especially in brain growth, which is very fast towards the end of pregnancy.
There are some circumstances where the doctor must induce the woman. There are other circumstances where women have an emergency cesarean section before their due date. For example, to prevent a stillbirth. However, the number of inductions is rising and there is concern that some women are having unnecessary early births.