A Matched Case-Control Study to Identify the Risk Factors for Gestational Diabetes Mellitus in a Tertiary Care Hospital in Chennai

Background Gestational diabetes mellitus (GDM), defined as impaired glucose tolerance first recognized during pregnancy, can lead to serious maternal and fetal complications. Therefore, this study aimed to identify its risk factors in a tertiary care hospital in Chennai. Methodology A hospital-based matched case-control study with age matching was conducted in a tertiary care hospital in Chennai from August 2023 to September 2024. Using the WHO single-step oral 75 g glucose tolerance test (OGTT), 103 cases and 103 controls were individually matched to diagnose GDM. A pretested structured questionnaire and an examination of medical records were used in the data collection process. The McNemar test and conditional logistic regression were used for statistical analysis. The results were presented as matched (mOR) and adjusted matched odds ratios (AmOR) with 95% confidence intervals. Results The majority of the 206 pregnant women in the study were between the ages of 22 and 30 (103 cases and 103 age-matched controls). Cases were more likely to be obese (BMI ≥23 kg/m² Asian cut-off). Age-matched univariable analysis (McNemar test) revealed a significant association between pre-pregnancy BMI ≥23 kg/m² and GDM (mOR = 5.71; 95% CI: 2.56-12.76). The most reliable independent predictor, according to multivariable conditional logistic regression, was pre-pregnancy overweight/obesity (AmOR = 7.01; 95% CI: 2.96-16.64). Conclusion The findings of this study suggest that routine BMI screening, targeted preconception counseling, and lifestyle modifications to avoid overweight and obesity among women of reproductive age are crucial tactics to lessen the burden of GDM and the difficulties it causes for mothers and fetuses.