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Nutrition and fetal growth: paradoxical effects in the overnourished adolescent sheep.
J Reprod Fertil Suppl. 1999; 54:385-99.JR

Abstract

Inappropriate maternal nutrient intake at key developmental timepoints during ovine pregnancy has a profound influence on the outcome of pregnancy and aspects of postnatal productivity. However, the responses to alterations in maternal nutrition in adult sheep are often highly variable and inconsistent between studies. The growing adolescent sheep provides a new, robust and nutritionally sensitive paradigm with which to study the causes, consequences and reversibility of prenatal growth restriction. Overnourishing the adolescent dam to promote rapid maternal growth throughout pregnancy results in a major restriction in placental mass, and leads to a significant decrease in birthweight relative to moderately fed, normally growing adolescents of equivalent gynaecological age. Maternal insulin and IGF-I concentrations are increased from an early stage of gestation in overnourished adolescent dams and these hormones ensure that the anabolic drive required to promote maternal tissue synthesis is initiated at a time when the nutrient requirements of the gravid uterus are low. The major restriction in fetal growth in rapidly growing dams occurs irrespective of high concentrations of essential nutrients in the maternal circulation and suggests that the small size or altered metabolic and transport capacity of the placenta is the primary constraint to fetal growth. The decrease in placental weight in the overnourished animals reflects a significant reduction in both fetal cotyledon number and mean cotyledon weight. The role of nutritionally mediated alterations in progesterone and the components of the IGF system in this early pregnancy placental phenomenon are being investigated. Nutritional switch-over studies have demonstrated that reducing maternal nutrient intake at the end of the first third of pregnancy can stimulate placental growth and enhance pregnancy outcome, but increasing nutrient intake at this time has a deleterious effect on placental development and fetal growth.

Authors+Show Affiliations

Rowett Research Institute, Bucksburn, Aberdeen, UK.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Review

Language

eng

PubMed ID

10692870

Citation

Wallace, J M., et al. "Nutrition and Fetal Growth: Paradoxical Effects in the Overnourished Adolescent Sheep." Journal of Reproduction and Fertility. Supplement, vol. 54, 1999, pp. 385-99.
Wallace JM, Bourke DA, Aitken RP. Nutrition and fetal growth: paradoxical effects in the overnourished adolescent sheep. J Reprod Fertil Suppl. 1999;54:385-99.
Wallace, J. M., Bourke, D. A., & Aitken, R. P. (1999). Nutrition and fetal growth: paradoxical effects in the overnourished adolescent sheep. Journal of Reproduction and Fertility. Supplement, 54, 385-99.
Wallace JM, Bourke DA, Aitken RP. Nutrition and Fetal Growth: Paradoxical Effects in the Overnourished Adolescent Sheep. J Reprod Fertil Suppl. 1999;54:385-99. PubMed PMID: 10692870.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Nutrition and fetal growth: paradoxical effects in the overnourished adolescent sheep. AU - Wallace,J M, AU - Bourke,D A, AU - Aitken,R P, PY - 2000/2/29/pubmed PY - 2000/3/18/medline PY - 2000/2/29/entrez SP - 385 EP - 99 JF - Journal of reproduction and fertility. Supplement JO - J. Reprod. Fertil. Suppl. VL - 54 N2 - Inappropriate maternal nutrient intake at key developmental timepoints during ovine pregnancy has a profound influence on the outcome of pregnancy and aspects of postnatal productivity. However, the responses to alterations in maternal nutrition in adult sheep are often highly variable and inconsistent between studies. The growing adolescent sheep provides a new, robust and nutritionally sensitive paradigm with which to study the causes, consequences and reversibility of prenatal growth restriction. Overnourishing the adolescent dam to promote rapid maternal growth throughout pregnancy results in a major restriction in placental mass, and leads to a significant decrease in birthweight relative to moderately fed, normally growing adolescents of equivalent gynaecological age. Maternal insulin and IGF-I concentrations are increased from an early stage of gestation in overnourished adolescent dams and these hormones ensure that the anabolic drive required to promote maternal tissue synthesis is initiated at a time when the nutrient requirements of the gravid uterus are low. The major restriction in fetal growth in rapidly growing dams occurs irrespective of high concentrations of essential nutrients in the maternal circulation and suggests that the small size or altered metabolic and transport capacity of the placenta is the primary constraint to fetal growth. The decrease in placental weight in the overnourished animals reflects a significant reduction in both fetal cotyledon number and mean cotyledon weight. The role of nutritionally mediated alterations in progesterone and the components of the IGF system in this early pregnancy placental phenomenon are being investigated. Nutritional switch-over studies have demonstrated that reducing maternal nutrient intake at the end of the first third of pregnancy can stimulate placental growth and enhance pregnancy outcome, but increasing nutrient intake at this time has a deleterious effect on placental development and fetal growth. SN - 0449-3087 UR - https://www.unboundmedicine.com/medline/citation/10692870/Nutrition_and_fetal_growth:_paradoxical_effects_in_the_overnourished_adolescent_sheep_ DB - PRIME DP - Unbound Medicine ER -