Submitted to: Journal of Animal Science
Publication Type: Review Article
Publication Acceptance Date: 2/4/2002
Publication Date: 12/20/2002
Citation: Vallet, J.L., Leymaster, K.A., Christenson, R.K. 2002. The influence of uterine function on embryonic and fetal survival. Journal of Animal Science. 80(E. Suppl. 2):E115-E125.
Technical Abstract: The secretion rate of growth factors and the delivery rate of nutrients by the uterus to the conceptus affects the growth rate, development and survival of the conceptus. Many growth factors are products of uterine tissue. Transport of some nutrients is aided by specific transporter molecules on the uterine endometrial epithelial cell, while others (e.g., retinol, iron, folate) are incorporated into uterine secreted proteins (e.g., retinol binding protein, uteroferrin, folate binding protein). The rate of production of these proteins during pregnancy profoundly affects pregnancy outcome. Both global and specific effects of uterine products on aspects of conceptus development can influence pregnancy success by entraining conceptus development, so that the uterine environment and the developmental stage of the conceptus match. For example, the uterus of the Meishan pig secretes less protein prior to elongation, which slows conceptus development, results in smaller placentas and smaller fetuses, and allows for greater litter size. Furthermore, in Occidental pig breeds, an earlier rise in progesterone at the beginning of pregnancy accelerates the onset of protein secretion, increases estrogen secretion by the conceptus, increases the size of the fetus in later pregnancy, and decreases litter size. Studies of fetal erythropoiesis also indicate that specific uterine products (uteroferrin, folate binding protein) are required for this important aspect of fetal development and that greater litter size is associated with improved erythropoiesis. Thus, manipulation of uterine function can modify conceptus development and impact pregnancy success in domestic livestock.