Risk of stillbirth from medications, illnesses and medical procedures

Associations between stillbirth and 14 medical exposures during pregnancy were examined using deliveries in 1984 in 10 California counties. Cases (n = 332) were stillbirths and infant deaths within 24 h of birth. Randomly selected live births served as controls (n = 357) and were frequency matched by maternal age and county. Using questionnaire and vital statistics data, logistic regression and proportional hazards modelling were performed with adjustment for potential confounders. The most prevalent exposures were ultrasound (65% of cases, 58% of controls) and acetaminophen (45% of cases, 54% of controls). Prescription pain medication, when taken in the first 2 gestational months, was strongly associated with stillbirths due to congenital anomalies (odds ratio = 7.5, 95% confidence interval [CI] 2.3, 24.1). First and second trimester use of prescription pain or migraine medication was positively associated with all stillbirths (rate ratio [RR] range 1.3-1.6). Fertility drugs were positively associated with stillbirths in total and stillbirths due to complications of the placenta, cord and membranes (RR = 1.8, 95% CI 0.8, 4.1; and RR = 2.5, 95% CI 0.9, 7.2 respectively). No associations were found for aspirin, amniocentesis, diagnostic X-rays or fever, consistent with previous studies. This report is among the few studies of specific causes of stillbirth and medical exposures by gestational time window.