Obstetrical factors governing the etiopathogenesis of lambdoid synostosis.

Lambdoid synostosis results in skull deformities of varying degrees characterized by occipital flattening over the involved suture and other compensatory changes in skull shape. Such changes include contralateral occipital bossing, contralateral frontal flattening, ipsilateral frontal bossing, and ipsilateral anteroinferior displacement of the pinna (ear shearing). These deformities tend to worsen during the first year of life. The etiology has been attributed to genetic factors and primary disorders of bone growth, in addition to secondary effects of other diseases and modulators of the in utero environment. To determine causal factors in the development of lambdoid synostosis, the authors reviewed medical records of the mothers of 13 children with lambdoid synostosis who were treated at the University Medical Center of the State University of New York at Stony Brook. Pre- and perinatal events, prior obstetrical, gynecological, medical, social, and family histories were considered. Births of normal infants immediately prior to and just after the affected babies were born were selected as controls. There is a significant association between increased duration of the first stage of labor and the development of lambdoid synostosis. Furthermore, our results indicate that this condition has a predilection toward male infants, and may be associated with preterm labor.