Postpartum depression is a leading cause of maternal death, but its diagnosis and treatment is spotty at best, negligent at worst.

Now San Diego-based start-up Dionysus Digital Health is pitching a blood test to check for the condition, even before symptoms appear. The company says it has pinpointed a gene linking a person’s moods more closely to hormonal changes. The test uses machine learning to compare epigenetics – how genes are expressed – in your blood sample with benchmarks developed during a decade of research into pregnant people who did and didn’t develop postpartum depression.