N.L. study shows C-sections may increase diabetes risk
MUN professor says further research needed to establish stronger association
The high rate of Type 1 diabetes among children in Newfoundland and Labrador remains somewhat of a mystery, but a new study from Memorial University’s Faculty of Medicine is helping further the link between the autoimmune deficiency and caesarean sections.
A recent study led by Dr. Leigh Anne Newhook found data from this province shows delivery by caesarean section, or C-section, may increase the risk for Type 1 diabetes in children.
“I think it’s important to say this research just shows there’s an association,” cautions Newhook, an associate professor of pediatrics in the faculty and the study’s senior investigator.
“I think it’s telling us something. It’s saying we need to look at this a bit more closely and see if there’s a link, because we don’t know what causes Type 1 diabetes, and we don’t know why it’s so high in Newfoundland compared to other places. (C-sections) may be one factor that’s of importance, but it’s not cause and effect.”
Newhook was joined on the study by researchers from the Newfoundland and Labrador Centre for Health Information (NLCHI) and Sharon Penney from the Janeway Pediatric Research Unit. Its results were published in a recent volume of the Journal of Environmental and Public Health.
While there have been a number of studies looking at risk factors originating from the time of birth in relation to Type 1 diabetes in children, Newhook said, there was not much research to suggest a connection to C-sections when the local research team began its work in 2009.
“It was a surprise when we sort of looked at the statistics that (a Csection) was the thing that came out positive,” said Newhook, reflecting on the study’s results.
The research relied on data from the Newfoundland and Labrador diabetes database and the live birth system maintained by NLCHI, focusing on children born from 1982 onwards diagnosed with Type 1 diabetes before the age of 15.
A recent meta-analysis consisting of 20 studies looking at their combined effects also suggests Csections are a risk factor for Type 1 diabetes in children.
The immune system of a child with Type 1 diabetes attacks insulin-producing beta cells in the pancreas. A lack of insulin-producing cells affects blood-sugar levels.
“Why that happens in an otherwise healthy child is not known,” said Newhook.
Genetic traits
A genetic predisposition is one factor, but Newhook said there are others, noting identical twins with identical genetic makeups have been known to individually develop Type 1 diabetes without the other twin ever doing so.
“We understand other things in the child’s environment have to happen or don’t have to happen in order for them to develop the disease,” she said.
One theory that has been proposed, said Newhook, is that a baby’s immune system is developed at a very early stage. One factor that may promote normal immune system development in a baby is how it encounters bacterias prior to birth.
“For a baby, if they’re born vaginally versus caesarean section, the type of bacteria is going to be different, that early bacteria,” said Newhook. “The intestine is now known to be very important for immune developments.”
While she cautions the bacteria theory is only a hypothesis, it merits further research, she said.
Among factors in which the study did not find significant asso- ciations with the risk of Type 1 diabetes were maternal age, birth weight and gestational age. In assessing its own weaknesses, the study notes that information was limited pertaining to fathers, limiting the study’s ability to consider paternal factors and family history.
Newhook said she would like to delve further into details concerning C-section births that would go beyond hospital data.
“One thing I’m interested in is why was the caesarean section done in the first place? Was it because the baby was under some distress? Was it because the mother was unwell and that’s why the caesarean section was done? Maybe it’s those factors that are more important, or maybe it’s the process of the C-section itself.”
Newhook notes that in relation to Canada, Newfoundland and Labrador has a comparatively high rate of C-section births — 30.9 per cent versus a national rate of 26.3 per cent based on 2005-06 figures. The study says the provincial rate in 2010 increased to 33 per cent.