Fetal intravenous nutritional supplementation ameliorates the development of embolization-induced growth retardation in sheep.

Since decreased transfer of nutrients into the fetus has been documented in many forms of intrauterine growth retardation, we evaluated whether increasing fetal nutrient availability would prevent the development of experimental growth retardation in fetal lambs. Fetuses were separated into three groups: E, animals growth retarded by repetitive uteroplacental embolization (n = 8); ES, animals treated as in E and given fetal femoral venous infusions of 5% glucose and 6.8% amino acids (n = 7); and C, controls (n = 8). The duration and density of embolization were the same in E and ES; initial physical and metabolic characteristics and gestation at delivery were similar in all groups. E birth weight was reduced 26% compared to C (2888 +/- 373 SEM g versus 3880 +/- 277 g, p less than 0.05); fetal/maternal weight ratio was decreased 35% (p less than 0.005) and ponderal index decreased 22% (p less than 0.005). Asymmetric growth retardation was indicated in E by an increased brain/body weight ratio (p less than 0.05). ES fetuses, in contrast, showed no differences from C in birth weight (3601 +/- 190 g) or body proportions. ES were larger than E, with a greater fetal/maternal weight ratio and ponderal index (p less than 0.05 for both). In E and ES, size at birth showed a positive relation to the amount of supplements received. The average daily supplementation rate correlated with the fetal/maternal weight ratio and with the ponderal index (for both r = 0.62, p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of intrauterine nutritional supplementation on fetal growth retardation.

The effects of fetal nutritional supplementation on experimentally induced growth retardation were investigated in third-trimester sheep. The control group, C, was fed ad libitum (n = 8). Group R received a protein- and calorie-restricted diet over the last 3 weeks of gestation (n = 8). Group RS was given the same restricted diet as group R, and fetal, intragastric supplements of amino acids and glucose (n = 7). Over the experimental period, maternal weight increased 4.1 +/- 0.6 kg in C but was stable in R and RS (p less than 0.01). R and RS ewes and fetuses showed biochemical evidence of malnutrition but the changes were less severe in the RS group (p less than 0.05). Nutrient levels did not change in group C ewes and fetuses. At delivery, R lambs were smaller in weight and length than RS or C (p less than 0.05); gestational ages were the same. Weights were: R, 2,702 +/- 182 g; RS, 3,235 +/- 121 g; and C, 3,290 +/- 297 g. R also had lower fetal to maternal weight ratios and higher brain to body weight ratios than RS or C (p less than or equal to 0.05). Placental size was reduced 28% in R compared to C (p less than 0.05) and was intermediate in RS. The disparity in fetal size was explained by differences in nutrient acquisition between groups. Over the experimental period, caloric intake rose 24% in C fetuses; near delivery, they had the highest umbilical uptakes of carbohydrate and alpha-amino nitrogen. After maternal diet was limited, R and RS fetuses had dramatic decreases in umbilical uptake of alpha-amino nitrogen and static umbilical uptakes of carbohydrate. Caloric intake fell 42% in R. RS fetuses, however, were receiving sufficient gastric supplementation so that umbilical + gastrointestinal carbohydrate uptake equalled that of controls, and entry of alpha-amino nitrogen and calories was intermediate, between those of R and C. Fetal oxygen consumption reflected the differences in nutrient uptake, being greatest in C, lowest in R and intermediate in RS. Fetal supplementation lessened the drain on maternal nutrients and promoted more normal fetal growth and metabolism.