Association between perinatal and obstetric factors and early age at diagnosis of type 1 diabetes mellitus: a cohort study.

OBJECTIVES: To evaluate the association between perinatal and obstetric factors as potential triggers for the early onset of T1DM. METHODS: This was a retrospective cohort study enrolling 409 patients diagnosed with T1DM, in Bauru, São Paulo, Brazil, from 1981 to 2023. Data were retrieved from medical records, regarding sociodemographic parameters as age, sex, ethnicity, and socioeconomic status. Perinatal and obstetric factors as delivery type, gestational age, filiation order, length of exclusive breastfeeding, maternal age, maternal and fetal blood types, and occurrence of maternal gestational diabetes were also analyzed. An adapted survival analysis was employed to gauge the impact of each assessed variable at the age of T1DM diagnosis. RESULTS: The median age of T1DM diagnosis was 10.3 years with an interquartile range between 6.4 and 15.5 years. Delivery type and filiation order were the only factors statistically significantly associated with an early age at T1DM diagnosis. Patients who were born through cesarean section and who were firstborns showed a 28.6 and 18.0 % lower age at T1DM diagnosis, respectively, compared to those born through vaginal delivery and those that were nonfirstborns. CONCLUSIONS: Being born by cesarean section and being firstborn showed to be statistically significant factors to determine an early T1DM diagnosis.