Women who have planned caesarean sections because they have had previous C-sections should wait until the baby is at 39 weeks gestation, warns new research, which found that babies born prior to 39 weeks are at greater risk for a number of health complications.
The study included more than 13,000 women who had scheduled C-sections because they had previously had a C-section and not for other health reasons.
The babies born at 37 or 38 weeks gestation had higher rates of breathing difficulties, blood-sugar problems and infections, and were more likely to be admitted to the neonatal intensive care unit (NICU), compared to babies born at 39 weeks.
Specifically, babies born at 37 weeks were as much as four times more likely than babies born at 39 weeks to have breathing problems that required them to be put on a ventilator, acquire a severe bacterial infection, have low blood sugar or require admission to the NICU.
Babies born at 38 weeks were twice as likely to have one or more of the above complications compared to babies born at 39 weeks.
In their study, the researchers also found that about 36 per cent of C-sections were being performed prior to 39 weeks, and warned both doctors and patients to wait unless there is a medical reason for performing the procedure earlier.
"What we found is there's a very tiny window between 39 and 40 weeks where baby outcomes are optimal, and any deviation before or after that 39th week results in increased risk," study co-author Dr. John Thorp, of the obstetrics and gynecology department at the University of North Carolina at Chapel Hill, said in a statement.
"Babies born prior to 39 weeks have more feeding difficulties, more breathing difficulties and need more medical support, whether it be artificial ventilation or oxygen support or some form of tube feeding," Thorp went on to say.
"So it seems like there is a critical window to do these repeat Caesarean sections in the absence of labour."
According to Thorp, doctors should subtract seven days from a patient's due date. Any time within that seven-day period would be an "optimal" time for a C-section, he said.
The findings are published in the New England Journal of Medicine.
The research is significant given that C-section rates are on the rise. In the U.S., Caesarean sections accounted for 21 per cent of births in 1996, a figure that jumped to 31 per cent ten years later.
Statistics released last summer showed that the C-section rate in Canada has also jumped, from 17.6 per cent in 1993 to 26.3 per cent in 2006.
The spike corresponds with an increasing number of elective C-sections being performed. Many of these are done prior to 39 weeks, partly for scheduling convenience for both patient and doctor, Thorp said.
However, research has long shown that babies born before 39 weeks, whether vaginally or via C-section, are at risk for a host of health complications. As well, babies born via C-section are at greater risk for respiratory problems even when they are delivered at full term.
As well, C-sections involve substantially longer recovery times for mothers and carry risks of infection, bleeding, scarring, chronic pelvic pain and damage to the intestines or bladder.
According to study co-author Catherine Spong, women may not feel that there is a significant risk to the baby given that it's only a 14 day difference between 37 and 39 weeks.
"People might think the risks are small," Spong told Â鶹´«Ã½. "It's only a day or two, what does it really matter."
However, she warns that if the pregnancy is going well, the mother is not in labour and there is nothing pushing them to deliver early, then they should wait.
With a report from CTV medical specialist Avis Favaro and producer Elizabeth St. Philip
