The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) created the Stillbirth Collaborative Research Network to ascertain stillbirth causes in racially and geographically diverse populations in the United States. From this, the Stillbirth Collaborative Research Network Writing Group (201a1b) examined reasons for death at 20 weeks' gestation or later between 2006 and 2008 in 59 tertiary care and community hospitals in ive states. Standardized evaluations included autopsy, placental histology, and testing of maternal or fetal bloodltissues, including fetal karyotyping. Evaluations were performed in 500 women with 512 stillbirths. Of these losses, 83 percent were before labor. Causes of stillbirth were divided into eight categories shown in Table hese categories were then classified as probable, possible, or unknown. As an example, diabetes was considered a probable cause if the fetus had diabetic embryopathy with lethal anomalies or the mother had diabetic ketoacidosis. It was a possible cause if the mother had poor glycemic control and the fetus had abnormal growth. Overal, a probable or possible source was identiied in 76 percent of cases.
This Network study is unprecedented in the United States for several reasons. It was a population-based cohort of
TABLE 35-1. Causes of 512 Stillbirths in the Stillbirth Collaborative Research Network Study
Percentages are rounded and total more than 100 percent because some stillbirths had more than one cause. Overall, a cause was identified in 76 percent of stillbirths.
Data from Stillbirth Research Network Writing Group, 201n1 b.
stillbirths, in which all underwent systematic and thorough evaluation. Each assigned cause of fetal death is reasonably straightforward and comprehensible except for "placental abnormalities." This category contains "uteroplacental insufficiency" and a few other less clearly defined placental entities. his aside, the leading reasons for fetal death were obstetrical and primarily included abruption, multifetal gestation complications, and spontaneous labor or ruptured membranes before viability. Importantly, this study illustrated that systematic evaluation may identiy a likely cause in approximately three fourths of stillbirths. his rate is considerably higher than those in most prior analyses and serves to emphasize the importance of careful examination.
Many factors are associated with an increased risk of stillbirth. Among others, these include advanced maternal age; AfricanAmerican race; smoking; illicit drug use; maternal medical diseases-such as overt. diabetes or chronic hypertension; assisted reproductive technology; nulliparity; obesity; and prior adverse pregnancy outcomes-such as prior preterm birth or growth-restricted newborn (Reddy, 2010; Varner, 2014).
Two major studies have assessed whether stillbirth risk factors could be identiied either before or shortly after pregnancy confirmation. In the first, Reddy and colleagues (2010) analyzed data from the NICHD Consortium on Safe Labor. Briely, the pregnancy outcomes of 206,969 women delivered between 2002 and 2008 at 19 hospitals in the United States were analyzed. When the distribution of stillbirths according to gestational age was studied, the tragedy of stillbirth occurred primarily in term pregnancies. hese investigators concluded that their results did not support routine antenatal surveillance for any demographic risk factors.