Effect of Maternal Retroplacental Leiomyomas on Fetal Growth

Leiomyomas or fibroids are benign tumors that grow from smooth muscle cells and occur most commonly within the uterine wall. The presence of uterine leiomyomas in pregnancy has been associated with fetal growth restriction, malpresentation, cesarean delivery, premature birth, placenta previa, and fetal death, although not all studies support an increased risk of adverse outcomes. The location of myomas within the uterus can vary, and there is no published evidence on the variable effects of uterine leiomyomas depending on location, including a retroplacental location. This retrospective cohort study was conducted to determine the impact on fetal growth of the presence of 1 or more retroplacental leiomyomas. The study included 141 patients with leiomyomas identified by ultrasound and a control group of patients with no leiomyoma reported. Patients were identified fromthe medical records from 2007 to 2012; the control group was selected using a systematic random sampling method. The study analyzed the association of fetal growth with the number of retroplacental leiomyomas and their size and also recorded the occurrence of small-for-gestational-age (SGA) infants. The number of retroplacental leiomyomas did not significantly impact pregnancy outcomes. A higher rate of SGA infants, although not significant, was found in mothers with leiomyomas (odds ratio [OR], 2.58; 95% confidence interval [CI], 0.97-6.84; P = 0.057). Women who had a retroplacental leiomyoma of more than 4 cm in mean diameter were more likely to deliver an SGA infant (OR, 2.84; 95% CI, 1.01-8.01; P = 0.048). In the control group, birth weight was at least 177 g higher (95% CI, -295 to -95; P = 0.003). The authors concluded that lower birth weight is prevalent among infants born to mothers with single or multiple retroplacental leiomyomas and that the risk of delivering SGA infants increased with the size of retroplacental leiomyomas. This was more obvious in cases where the mean diameter of the leiomyomas was greater than 4 cm.