Stillbirths in Macaca fascicularis

BACKGROUND: Stillbirths in non-human primates are a major problem and represent failure of the maternal-fetal-placental unit to maintain normal relationships because of various endogenous, undetermined or environmental factors. METHODS: Records of 236 stillborns and their dams in a Macaca fascicularis colony during a 7-year period were reviewed retrospectively. RESULTS: The 7-year stillbirth incidence was 11.99% (236 stillbirths, 1967 live births). Most (61.02%, n = 144) were of undetermined etiology. Fetal causes included trauma (22.46%, n = 53), fetal pneumonia (0.85%, n = 2) and congenital anomalies (0.42%, n = 1). Maternal causes included dystocia (9.75%, n = 23) and uterine rupture (0.42%, n = 1). Forty-nine placentas were available for histologic evaluation; there was placentitis in five, necrosis in five and placental abruption in two. Most stillbirths occurred close to term. First stillbirths usually occurred in 8- to 12-year-old animals during the first six pregnancies. CONCLUSIONS: Most stillbirths were of undetermined etiology. Fetal trauma was the most common cause.