[An epidemiological study of oligohydramnios associated with congenital malformations]

Our registry of congenital anomalies allows us to study systematically pregnancies which ended in the birth of a malformed child. Over 8 years 105,374 births were registered. A control was selected for each malformed baby. Numerous factors are studied. One of them is oligohydramnios. During the study period 199 children carriers of at least one congenital major malformation were born after a pregnancy complicated by oligohydramnios; which represent an incidence of 1.88%. Overall 2,787 malformed children were born during the study period, 7.14% of them were born after oligohydramnios (controls 1.6%, p less than 0.001). The malformations which were more often associated with oligohydramnios involved the urinary system (15.9%), the digestive system (10.2%), the genital system (5.9%) and the limbs (5.7%). A chromosomal aberrations was present in 11 infants (5.5%). Most of the isolated malformations were not associated with oligohydramnios, whereas the pregnancies which ended with the birth of a malformed baby were often complicated by oligohydramnios. Therefore when a fetal malformation is discovered during pregnancy the obstetrician should not be satisfied with the discovery of one anomaly associated with oligohydramnios. He (she) has to look carefully for other associated fetal malformations. The weight, the length and the head circumference at birth of the children born after oligohydramnios were less than those of the controls (p less than 0.001). The length of gestation was shorter (p less than 0.01). The weight of the placenta was smaller. In this study the only maternal factors which favoured the occurrence of oligohydramnios were diabetes and epilepsy.