RELATIONSHIPS BETWEEN FETAL WEIGHT, PLACENTAL WEIGHT AND MATERNAL PLACENTAL CIRCULATION IN THE RABBIT AT DIFFERENT STAGES OF GESTATION

Abstract

Summary. Fetal weights, placental weights, myometrial, vaginal and maternal placental blood flows (estimated with radioactive micro-spheres) were measured in forty-one rabbits at 16, 20, 24 or 28 days of gestation; term occurs around Day 31. Multiple linear regression analysis indicated that fetal weight and placental weight were positively related at all stages of gestation examined. Fetal weight and placental blood flow were negatively related at Day 16, but positively related at Days 20, 24 and 28. The conceptus adjacent to the ovary had greater placental weight and flow values than the means from all conceptuses in the horn by Day 20 but fetal weight was only greater by Day 28. The relevance of these findings to the determination of fetal weight is discussed.