Fetal micrognathia: associated anomalies and outcome.

The purpose of this study was to evaluate the spectrum of sonographic findings, karyotypic abnormalities, and clinical outcome in cases of fetal micrognathia. Twenty fetuses with sonographically identified micrognathia were identified between 15 weeks' gestation and term. Five of 20 fetuses (25%) had abnormal karyotypes, including three with trisomy 18 and one each with trisomy 13 and trisomy 9. Sixteen of the 20 fetuses (80%) did not survive: Ten died in utero or during the neonatal period, and six pregnancies were terminated electively. Three of 20 fetuses (15%) had micrognathia as the sole sonographic finding. Two of these fetuses survived, one with growth retardation and one with Pierre Robin syndrome. Thirteen of 20 pregnancies were complicated by polyhydramnios. The diversity of the syndromes represented in our cases of micrognathia indicates a wide breadth of possible diagnoses when micrognathia is encountered prenatally. The poor prognosis and associated karyotypic and lethal anomalies are remarkable, with survival of only four of 20 fetuses in this report.