Causal analysis of fetal death in high-risk pregnancies

Objectives: To determine the causes of fetal death among the stillbirths using two classification systems from 22 weeks of gestation in a period of three years in high-risk pregnancies. This is a retrospective observational study. Methods: The National Institute of Perinatal Health in Mexico City is a Level 3 care referral center attending high-risk pregnancies from throughout the country. The population consisted of patients with fetal death during a threeyear period. Between January 2016 and December 2018, all stillbirths were examined in the Pathology Department by a pathologist and a medical geneticist. Stillbirth was defined as a fetal death occurring after 22 weeks of gestation. Results: Main outcome measures: Causal analysis of fetal death using the International Statistical Classification of Disease and Related Health Problems-Perinatal Mortality (ICD-PM) and initial causes of fetal death (INCODE) classification systems. A total of 297 stillborn neonates were studied. The distribution of gestational age in antepartum stillbirths (55.2%) showed a bimodal curve, 36% occurred between 24 and 27 weeks and 32% between 32 and 36 weeks. In comparison, the majority (86%) of intrapartum deaths (44.8%) were less than 28 weeks of gestation. Of the 273 women enrolled, 93 (34%) consented to a complete fetal autopsy. The INCODE system showed a present cause in 42%, a possible cause in 54% and a probable cause in 93% of patients. Conclusions: The principal causes of antepartum death were fetal abnormalities and pathologic placental conditions and the principal causes of intrapartum death were complications of pregnancy which caused a premature labor and infections.