Effects of initial body mass index on development of gestational diabetes in a rural Sri Lankan population: A case-control study.

AIM: High pre-pregnancy body mass index (BMI) and excessive pregnancy weight gain lead to higher incidence of gestational diabetes mellitus (GDM). Aim of the study was to assess the effects of initial BMI and pregnancy weight gain on development of GDM in a rural Sri Lankan population. It was also hypothesized that these effects could be more pronounced in shorter mothers.

METHODS: A case-control study was conducted at two rural hospitals in Sri Lanka. A case was defined as a pregnant mother admitted for the completion of pregnancy and diagnosed to have GDM (n=99). A similar group of mothers without GDM were recruited as controls (n=336). Data were collected through health records and direct interviews.

RESULTS: Mean age of GDM and non-GDM mothers were 32.8 years 28.1 years, respectively. High pre-pregnancy BMI was a significant risk for GDM, with a rising trend with increasing BMI. In contrast to underweight mothers, the risk increases from normal weight [odds ratio (OR)=6.6, 95% confidence interval (CI) 2.2-19.4, p<0.01], overweight (OR=17.1, 95% CI 5.8-49.9, p<0.01) and to obese (OR=32.4, 95% CI 10.0-104.5, p<0.01). There was no significant difference in weight gain across mother's height groups. Height or leg length did not show an association with GDM. Family history of diabetes and past GDM were associated with GDM. GDM mothers had higher likelihood for cesarian deliveries, and babies with higher birth weight.

CONCLUSION: The pre-pregnancy BMI was the most important modifiable risk factor for GDM, and it should be the main preventive measure.