Severe Maternal Morbidity Among Adolescents Aged 10-19 in California, 2001-2020.

Purpose: To examine the prevalence of severe maternal morbidity (SMM) and the indicators (i.e., morbidities and procedures) that comprise the SMM composite among adolescents and to compare risks between adolescents and adults.

Methods: This was a population-based study in California to individuals aged 10-55. We included prenatal, postpartum, and birth hospital discharge records linked to vital records from 2001 to 2020. SMM was defined using the Centers for Disease Control and Prevention index. We estimated adjusted risk ratios (RRs) using modified Poisson regression models.

Results: This study included 702,481 adolescent births among 9,529,689 total births. There were 19 cases of SMM per 1,000 adolescent births; prevalence was highest among those aged 10-14 (27.5). Compared to adults aged 25-29, adolescents had higher rates of blood transfusion (11.4 vs. 9.0) and eclampsia (2.3 vs. 0.8). Crude RRs for SMM were 1.18 (95% confidence interval [CI]: 1.15-1.21), 1.22 (95% CI: 1.18-1.26), and 1.74 (95% CI: 1.53-1.99) in ages 18-19, 15-17, and 10-14, respectively. Adjustments for payer, race/ethnicity, parity, and anemia explained excess risk among ages 15-19, but not the youngest adolescents (10-14 years; RR: 1.31; 95% CI: 1.15-1.49). Patterns of SMM risk were similar but less pronounced when excluding blood transfusions. Risks were also elevated among ages 30-34, 35-39, and 40-55.

Discussion: Adolescents are at increased risk for SMM compared to adults, largely explained by social disadvantage, parity, and anemia, but not prepregnancy comorbidities. These findings highlight the need for resources to prevent SMM in adolescents and should be considered during care and public health planning.