Impact of placenta previa on intrauterine fetal growth.

The impact of placenta previa on intrauterine fetal growth was studied over a 10-year period, 1968-77. Fetal growth was assessed at the time of delivery by measurement of four parameters--birthweight, length, and head and chest circumferences. For 129 deliveries associated with placenta previa, these parameters were plotted against gestational age on Usher and McLean intrauterine growth curves. Fetal growth was significantly retarded as judged by all four parameters. When the results were analyzed according to the number of vaginal bleeding episodes, different patterns were found for the parameters studied. Retardation in chest circumference was unrelated to gestational age or number of bleeding episodes. Retardation in weight and chest circumference appeared at an early gestational age (25th week) and was more pronounced in the group with repeated episodes of bleeding. Retardation in head circumference and length appeared later (from the 32nd week of gestation) and was also more pronounced in the group with repeated vaginal bleeding. In women who had only one bleeding episode and in whom gestation continued to the 38th week or longer, birthweight, but none of the other three parameters, was consistent with the week of gestation. The results show that birthweight alone is insufficient to estimate intrauterine fetal growth retardation.