Subclinical intrauterine infections during pregnancy in Mozambican women were studied in an attempt to elucidate their potential association with adverse pregnancy outcome, particularly stillbirth and preterm birth. A total of 39 stillbirths and 21 preterm live births were compared with 121 term live births. Extraplacental membranes and amniotic fluid were studied to ascertain the presence or absence of chorioamnionitis and of antibacterial activity in amniotic fluid. It was found that signs of maternal subclinical disease in extraplacental membranes in combination with an absence of antibacterial activity in amniotic fluid was overrepresented in stillbirths and preterm births in relation to term live births. A tentative conclusion is that a lack of antibacterial activity in amniotic fluid and established chorioamnionitis represent a vicious combination with strongly negative significance for the fetal outcome.