Newborn baby
A premature baby at Civil Hospital (CHU) waits in an incubator during the relocation of the hospital of Charleroi, southern Belgium, to another one a few miles away, October 18, 2014. Reuters/Yves Herman

Natural birth appears to have fewer risks compared to caesareans for both mothers and their children. Women who have caesareans are likely to have increased risks of placenta problems, stillbirths and future miscarriages, a new analysis suggests.

University of Western Australia researchers and their Scots colleagues looked into data from 80 different studies that involved nearly 30 million women. They sought to establish the benefits as well as the long-term risks of caesareans compared to natural births.

Among the findings was that mothers who went on to have further pregnancies looked more at risk of stillbirth, miscarriage and placenta problems. Kids born by caesarean deliveries appeared to have an increased risk of obesity up to five years of age. They are also more likely to suffer asthma for up to 12 years.

A review found that an average of 9.2 in every 100 children born naturally was obese before the age of five. The number rises to nearly 14 out of every 100 children for those who were surgically removed from the womb. Asthma rates rose from about 3.05 in 100 babies born the natural way to 3.65 in every 100 born through caesarean delivery.

It is believed that the 51 percent increased risk is due to the lack of exposure to important bacteria as the baby passes through the birth canal. There may be a potential effect on the babies’ metabolism and the ability of their body to store fat.

Researchers suggest that women and doctors must be aware that caesareans have been linked with long-term risks, which include future pregnancies. But they can't definitively say caesarean cause particular outcomes.

“Although we cannot conclude that caesarean delivery causes certain outcomes, pregnant women and clinicians should be aware that caesarean delivery is associated with long-term risks for the baby and for subsequent pregnancies,” Dr Sarah Stock, co-author of the review from the MRC Centre for Reproductive Health at the University of Edinburg, said. The researchers added that the significance that women attribute to these individual risks is likely to vary.

There have been previous studies looking into the short-term health risks linked with caesareans. These include increased likelihood of hysterectomies, surgical complications and death from blood clots. As for its benefits, researchers have found that caesarean deliveries were associated with a decreased risk of urinary incontinence and pelvic prolapse for women.