- Researchers analysed 938,798 pregnancies and found gestational diabetes prevalence rose from 1.5% in 2015 to 6.6% in 2023.
- The rise was steepest among women with lower incomes, lower educational attainment and those born outside Sweden.
- The study cannot show that socioeconomic circumstances directly caused gestational diabetes, and Swedish results cannot automatically be transferred to the UK.
A diagnosis of gestational diabetes is becoming more common – but the increase is not being shared equally across society.
Researchers at Karolinska Institutet analysed 938,798 singleton pregnancies recorded in Sweden between 2015 and 2023.
They linked pregnancy records with national information on income, education and country or region of birth.
Across that period, gestational diabetes prevalence increased from 1.5% to 6.6%.
The increase was steepest among women born outside Sweden, those with lower educational attainment and those living on lower incomes.
That is a substantial rise.
But it should not automatically be interpreted as evidence that diabetes suddenly became four times more common because people’s biology changed.
Screening practices and diagnostic criteria also changed during the study period, and these can affect how many cases are detected.
The researchers nevertheless found clear social differences even after accounting for a range of other characteristics.
Gestational diabetes develops when the body cannot produce enough insulin to overcome the increased insulin resistance of pregnancy.
It causes and can increase the risk of complications for both mother and baby.
The Swedish study found that gestational diabetes was associated with pregnancy, obstetric, postpartum and neonatal complications.
But the strength of those associations varied between social groups.
For example, among Swedish-born women, gestational diabetes was associated with 71% higher odds of obstetric complications compared with Swedish-born women without gestational diabetes.
The relative increase was smaller among women born in Africa and the Eastern Mediterranean region.
That does not mean those groups had healthier pregnancies.
Some groups, including women born in Africa and Southeast Asia, had higher overall – or absolute – rates of complications.
This distinction between relative and absolute risk is important when discussing health inequalities.
There are several possible explanations.
Access to healthcare, language, income, food environment, housing, employment conditions and differences in underlying health can all influence pregnancy outcomes.
Diagnostic practices may also differ between populations and regions.
Because this was a registry study, it cannot determine which of those factors caused the differences.
Researchers also lacked detailed data on factors such as sleep, physical activity and social support.
The results therefore show inequality, not a single biological explanation for it.
The findings are highly relevant to UK maternity services even though the exact Swedish figures should not be imported directly.
