Extrinsic fetal akinesia and skeletal development: a study in oligohydramnios sequence.

Long-bone morphometry and cephalometry were performed in 13 newborns with oligohydramnios sequence (OS) in order to establish whether or not skeletal changes existed in extrinsic fetal akinesia similar to those observed in the fetal akinesia deformative sequence (FADS) (i.e., hypoplastic long bones and micrognathia). Oligohydramnios sequence was caused by bilateral renal agenesis in five cases and obstructive uropathy in eight cases. Twenty-one stillborns and newborns who had died from conditions other than renal anomalies or congenital malformations were used as controls. Normal longitudinal and periosteal long-bone growth and absence of micrognathia were found in OS patients. Skeletal differences between FADS and OS may be explained not only by timing, duration, and degree of reduced motility but also, and more importantly, by the normal muscular stress in OS patients.