A new study by the University of Adelaide has for the first time confirmed a seasonal variation in gestational diabetes.

Women who conceive babies in winter are more likely to develop gestational diabetes during pregnancy, a new study shows.

The University of Adelaide study, which analysed 60,000 births in South Australia over a five-year period, has for the first time confirmed a seasonal variation in gestational diabetes.

The research, published on Tuesday, found women who fell pregnant in winter were more likely to develop the condition, with 6.6 per cent affected compared to 5.4 per cent of summer conceptions.

It also suggested the overall incidence of gestational diabetes is on the rise, with 4.9 per cent of pregnancies affected in the first year of the study 2007 compared to 7.2 per cent in 2011.

"Our study is the first of its kind to find strong evidence of a relationship between gestational diabetes and the season in which a child is conceived," lead author Dr Petra Verburg said.

She says the researchers will now conduct further work that will investigate reasons for the results.

"The mechanisms that cause gestational diabetes are still not fully understood," Dr Verburg said.

"Previous studies have suggested that meteorological factors, physical activity, diet and vitamin D are risk factors for gestational diabetes, all of which are impacted by the winter season."

The study, which also involved the University of Groningen in the Netherlands, was published in the journal BMJ Diabetes Research & Care.