THE EXACT role of maternal factors in the pathogenesis of the respiratory distress syndrome (RDS) remains unresolved despite the availability of considerable statistical data. In a recent review of the experience with the RDS at the Wilford Hall USAF Hospital, it was noted that several mothers delivered successive small infants who developed the RDS. This suggested that the low birth weight infants of some mothers were predisposed to the development of the RDS irrespective of the complications of a particular pregnancy. It is the purpose of this report to present data relevant to this question. Materials and MethodsThe records of all mothers who delivered more than one infant weighing between 900 and 2,500 gm from at the Wilford Hall USAF Hospital were reviewed with the records of their infants. One mother who delivered at the USAF Hospital, Laughlin AFB, Texas, is also included. For purposes of this review, infants weighing between 900 and 2,500 grams were considered to be of low birth weight (LBW). If all LBW infants of an individual mother had severe erythroblastosis, congenital anoma¬ lies incompatible with life, or suffered from asphyxia which resulted in death in the first two hours of life, the mother and the infants were excluded from fur¬ ther consideration. No attempt was made to estimate