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Maternal Age, BMI and Race Are Factors in Gestational Diabetes

Nov 4, 2011

Age and BMI are important factors in whether a woman will develop GDM, and those factors are particularly relevant in black African and South Asian women.

Early detection is critical to the effective treatment of GDM. Known risk factors include BMI, advanced maternal age, previous GDM or delivery of a large baby, family history of diabetes, and race.

Despite knowledge of these risk factors, few studies have looked at how they interact to influence GDM risk. Therefore, researchers conducted a retrospective study of associations between GDM and maternal age, BMI, and race, as well as how the factors interact with one another.

The study compared 1688 women who developed GDM between 1988 and 2000 with 172,632 women who did not. All the women were seen at 1 of 15 maternity units in London and had not previously given birth. Clinicians calculated at each woman’s BMI at her first antenatal visit and the women self-reported their maternal age and race (white European, black African, black Caribbean, or South Asian).

The researchers noted an association between greater maternal age and risk of GDM (P < .001) and between increasing BMI and risk of GDM (P < .001), but the effects varied greatly between women of different races.

To calculate odds ratios for developing GDM, the baseline comparison group was white Europeans aged 20 to 24 years. White European women aged 30 to 34 years had twice the risk of developing GDM, and those 40 years of age and older had a 4-fold increase in risk (P < .001).

Increasing age was associated with a much steeper increase in risk among black African women. Those aged 25 to 29 years had an odds ratio of 3.40 (again with white Europeans aged 20-24 years as the baseline comparison), those aged 35 to 39 years had an odds ratio of 13.67, and those aged 40 years and older had an odds ratio of 59.20, corresponding to a nearly 60-fold increase in the risk of developing GDM (P < .001).

Black Caribbean and South Asian women had odds ratios representing age-related levels of risk that were higher than those in white Europeans but lower than those in black Africans.

Compared with white Europeans with normal BMIs, black Africans and South Asians were more likely to develop GDM regardless of BMI.

“Advancing maternal age and BMI are more important risk factors for GDM in South Asian and Black African women than in White European or Black Caribbean women,” the authors write.

“The finding that older age and higher BMI interact with racial group in relation to the prevalence of GDM emphasizes the important public health message of healthy eating and weight control, which is particularly crucial in women of South Asian and Black African racial origin,” the authors conclude.

BJOG Published online November 2, 2011