Placental blood flow and fetal weight following uterine artery ligation. Temporal aspects of intrauterine growth retardation in the guinea pig.

Placental blood flow (microsphere distribution), placental weight and fetal weight were examined at three stages of gestation following unilateral uterine artery ligation at days 30-32 in 23 guinea pigs. Placental blood flow and placental weight were reduced in the ligated horn at days 45, 55, and 65. The fetal weight was decreased at days 55 and 65. We suggest that ligation of the uterine artery reduces placental blood flow which, in turn, restricts placental growth without any significant effect on fetal weight before day 45. At this stage of gestation no correlation was found between fetal weight and placental blood flow. Later in gestation, however, fetal growth becomes limited by placental blood flow, and between days 45 and 55 ligation impedes the increase in blood flow, and consequently the fetal growth rate declines.