Background First-trimester​​​​​​ missed abortion, that is, the death of the embryo or fetus without expulsion, is still the leading cause of pregnancy loss in the early stages, both worldwide and in India. The incidence of this event is a cry of demographic, metabolic, obstetric, and lifestyle-related maternal factors, with the respective patterns showing considerable differences from one region to another. Localized evidence is very important for the early warning of at-risk pregnancies. This research describes the distribution of maternal risk factors for the first-trimester missed abortion in the tertiary care population of South India. Methods A hospital-based cross-sectional study was carried out at a tertiary-level center in Chennai from May 2025 to November 2025. The study sample included pregnant women in the first trimester. A standardized ultrasonographic criterion was used to confirm the missed abortion. Information on maternal sociodemographic characteristics, obstetric history, medical comorbidities, anthropometric indices, laboratory parameters, lifestyle exposures, and psychosocial factors was collected using a structured proforma. The associations were analyzed through the univariate method, and the variables meeting the inclusion criteria were subjected to multivariate logistic regression for the identification of independent factors. Results The study included 200 pregnant women, with 100 cases of first-trimester missed abortion and 100 matched controls. Advanced maternal age (>35 years) was significantly associated with missed abortion; 48 (48%) of cases were above 35 years compared with 16 (16%) of controls (adjusted odds ratio (AOR): 4.23; 95% confidence interval (CI): 2.10-8.52). Obesity (BMI ≥30 kg/m²) was more prevalent in cases (36%) than controls (12%) and showed a strong association (AOR: 3.67; 95% CI: 1.72-7.83). Gestational diabetes mellitus (GDM) occurred in 30% of cases versus 10% of controls (AOR: 3.89; 95% CI: 1.68-8.97). Previous pregnancy loss (22, 22%), consanguinity (28, 28%) and high perceived stress levels (26, 26%) were more frequent among cases but did not retain statistical significance in multivariate analysis. Conclusion This research reveals that maternal factors such as advanced age, obesity, and early gestational dysglycemia mainly contribute to the first-trimester missed abortion in the studied population. The elevated prevalence of anaemia, thyroid dysfunction, previous loss, and short interpregnancy interval exposes the multifactorial nature of early pregnancy failure. The results highlight the importance of preconception assessment, metabolic optimization, and early antenatal risk screening, which should be an integral part of the maternal health programs in India, especially considering the trend of lifestyle-related disorders and delayed ​​​​​​.

S H, M P, S MT, Selvam V. Association of Maternal Risk Factors With First-Trimester Missed Abortion: A Cross-Sectional Study. Cureus. 2025 Dec 31;17(12):e100503.