Effect of nutrient intake during pregnancy on fetal and placental growth and vascular development
Introduction
The relationship between maternal nutrient intake during pregnancy and the growth of the fetus is extremely important for determining pregnancy success and the life-long health and productivity of an individual [1], [2]. Since profitability in the livestock industry is dependent upon efficiency of production characteristics such as growth and development after birth, the precursor of efficiency, namely fetal growth, must be optimal. The size and nutrient transfer capacity of the placenta play a central role in determining the prenatal growth trajectory of the fetus and hence directly influences birth weight. Transplacental exchange is dependent upon uterine and umbilical blood flow, and these blood flows are in turn largely dependent on adequate vascularization of the placenta. This review focuses on the important relationships between maternal nutrition during pregnancy, placental growth and vascular development, and fetal growth.
Section snippets
Priority of partition of nutrients according to metabolic rate
During pregnancy, nutrients are generally partitioned to various tissues of the maternal body in priority order according to their metabolic rate (Fig. 1) [3], [4]. Thus, as nutrients become limiting, tissues with lower metabolic rates and hence reduced priority, will receive quantitatively less nutrients. Since highly metabolically active tissues receive greater rates of blood flow than less metabolically active tissues, rate of blood flow becomes the limiting factor for nutrient partitioning
Relationship of fetal weight and placental growth to stage of gestation
Although fetal organogenesis is largely complete during early gestation, exponential growth of the fetus is limited to the last third of pregnancy (Fig. 2), beginning around day 90 and ending around day 145 (term) in sheep. Thus, approximately 90% of fetal growth occurs during the last third of pregnancy. However, the majority of placental growth, at least in terms of placental mass, occurs during the first two-thirds of pregnancy, and the placenta achieves its maximum weight by day 90 in sheep
Effects of maternal nutrition on fetal growth
Undoubtedly, maternal nutritional status is one of the extrinsic factors programming nutrient partitioning and ultimately growth, development and function of the major fetal organ systems [1], [2], [11], [12], [13]. Indeed, the prenatal growth trajectory is sensitive to the direct and indirect effects of maternal dietary intake from even the earliest stages of embryonic life when the nutrient requirements for conceptus growth are negligible [14]. Furthermore, recent evidence in sheep suggest
An adolescent ewe paradigm for studying nutrition/fetal growth interactions
The data reviewed in the preceding section highlights both the importance of maternal nutrition to pregnancy outcome and the variability in response depending on when the nutritional treatments are applied and the age and growth status of the animals studied. The conflicting demands of maternal growth and appropriate nutrient partitioning to the fetus can largely be avoided in young domestic animal species by simply not allowing them to breed until their own body growth is complete. Substantial
Placental growth, vascular development and impact of maternal nutrition
The placenta is the organ through which respiratory gases, nutrients, and wastes are exchanged between the maternal and fetal systems. Thus, the size and nutrient transfer capacity of the placenta play a central role in determining the prenatal growth trajectory of the fetus and hence birth weight, postnatal viability and long-term health. As mentioned earlier, the growth of the placenta precedes that of the fetus and a strong positive association exists between placental mass and size at birth
Relationship between fetal growth and pregnancy outcome, life-long productivity and health
Factors such as maternal nutritional status and age or gynecological maturity can impinge on normal fetal growth and development and will ultimately affect pregnancy outcome. Characteristics of poor pregnancy outcome include premature births, low birth weight, and high mortality rates from birth to 1 year of age [47]. There is clear evidence that birth weight is correlated with a variety of production and/or health characteristics. In pigs for example, average daily gain is positively
Summary
Clearly, maternal nutrition during pregnancy is an important determinant of subsequent fetal growth and development, pregnancy outcome, and ultimately, life-long health and productivity of an individual. Mechanistically, maternal nutrition appears to impact placental growth and vascular bed development (angiogenesis), thereby affecting uteroplacental blood flows and nutrient uptakes by the fetus, all of which play an important role in fetal growth and metabolism, and birth weight. Furthermore,
Acknowledgments
The authors acknowledge support from the Scottish Exec. Environ. and Rural Affairs Dept., NIH HL64141, and ND Agr. Exp. Sta. Proj. 1705. We also wish to acknowledge our numerous collaborators and colleagues who are listed on the cited references from our laboratories.
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