Hamilton Health Sciences performs the highest rate of C-sections among teaching hospitals in Canada, at 32.85 per cent of all births at the facility, according to The Canadian Institute for Health Information (CIHI).

This rate includes data gathered from Hamilton Health Sciences' three teaching sites—McMaster University Medical Centre, Juravinski Hospital and Hamilton General Hospital. 

The report tracked births from April 1, 2011, to March 31, 2012. The finding was part of the non-profit organization's Canadian Hospital Reporting Project.

The national average for C-sections is 27.04 per cent, according to CIHI.

Dr. Nicholas Leyland, Chair of the Department of Obstetrics and Gynecology at McMaster University in Hamilton and chief of obstetrics at Hamilton Health Sciences, says that statistic doesn't tell the whole story about the incidences of C-sections, however.

McMaster deals with an above-average number of high-risk pregnancies from Hamilton and across the region, which explains the higher than average number of C-sections, he said.

"The reason is because the population that McMaster serves has much higher acuity than any other tertiary care centre which are also teaching hospitals. [McMaster is] receiving more referrals of complex-medically or complex-surgically patients that are pregnant," Leyland said.

He explained that "higher acuity" refers to patients that come to the hospital with other medical issues in addition to pregnancy.

"That means there are other factors that make the higher risk. Some of those factors are things like complicated diabetics, patients with cardiac disease, patients with many other medical complications [such as] lupus. Obesity is another one ... these patients are more likely to require delivery by caesarean section."

Leyland points out that when it comes to low-risk births, McMaster has one of the lowest C-section rates in the country.

"If you separate the low-risk population, which is a very small percentage of our deliveries at McMaster, the section rate in that group is as low as anyone's across Canada. The fact is that when patients become more complicated ... they more frequently require delivery by caeserean section."

Leyland says pregnant women in Hamilton shouldn't fear that they'll be more likely to have a C-section at McMaster than at other hospitals.

"If they are patients with low risk than they are at no greater risk of having a C-section [at McMaster] than at any other hospital."

Asthma, allergy associated with C-section

An estimated 25 per cent of births in Canada are as a result of caesarean.  

Concern about how babies are delivered and the potential effects on their health over the long-term is a growing subject of research.

A recent study affiliated with McMaster University suggests there may be a link between an increased risk of asthma and allergies, and caesarean deliveries. The study found that babies born by C-section had fewer and less diverse digestive bacteria, a factor that affects immune system development and which may in turn make them more susceptible to developing asthma and allergies. 

That same study suggested the same effect for babies who were fed formula rather than breastfed.

Dr. Malcolm Sears, one of the study's authors and a leading asthma and allergy researcher at McMaster and St. Joseph's Healthcare, says the study is part of a larger investigation into what is driving the development of asthma and allergy.

"There is clear evidence that babies born by C-section have a 20 per cent increased risk of asthma," he said. "The question has always been: why?"

The study is by no means conclusive, said Sears, but represents only a "preliminary finding."  However, he added, it is important to consider how delivery methods may have an impact on infant health.

"There is an increasing trend toward cesareans," said Sears, "...but if it increases the risk of a health outcome" there should be greater discussion surrounding the practice.

Dr. Leyland, who is familiar with the study's findings, said that in the future it may alter how infants are treated after a C-section. For example, he suggested that the use of probiotics could positively influence digestive health.