Influence of intrauterine position on fetal weight in Dutch belted rabbits

The influence of intrauterine position on fetal body weight was statistically evaluated for 199 Dutch belted rabbit litters from does receiving various treatments during teratological studies. The data consisted of the number, type (live, dead, resorbed), and position of implantation sites in the left and right uterine horns. Body weights of live fetuses were also recorded. No statistically significant relation was found between the number of live, dead, or resorbed fetuses and intrauterine position. An effect related to differences in position between the left and right uterine horns for the proportions of largest fetuses was statistically significant. This uterine horn effect was not seen for the proportions of smallest fetuses. Positional differences within the uterine horns were significant and indicated a decrease in the proportion of largest fetuses and an increase in the proportion of smallest fetuses with increasing position number (ovarian to cervical end). Mean fetal weights differed significantly between the two uterine horns and among positions. There was a monotonic decrease in fetal weight with increasing position number. There were no significant associations between uterine horn or position and mean weight for the largest fetuses, but statistical evidence of the position effect was seen for weights of the smallest fetuses.