Transamniotic fetal feeding: enhancement of growth in a rabbit model of intrauterine growth retardation.

BACKGROUND

Transamniotic fetal feeding has been proposed as prenatal treatment for intrauterine growth retardation as substrates infused into the amniotic cavity are swallowed and absorbed. The rabbit provides an optimal model of intrauterine growth retardation in that a consistent weight ratio of the runt to the favored fetus is found at term.

METHODS

Thirty growth-retarded rabbit fetuses underwent transamniotic catheterization in the third trimester with incremental infusion of either dextrose, dextrose plus amino acids, or bovine amniotic fluid. One week later fetal weights were determined. The ipsilateral favored fetus served as an operated, noninfused control.

RESULTS

Fetuses receiving amniotic fluid showed significantly increased somatic growth when analyzed by absolute body weight and by weight ratio versus control. Increases in the liver, lung, and small intestinal weights of the fetuses receiving amniotic fluid paralleled the overall increase in somatic weight. No differences were found in the dextrose or dextrose plus amino acid-infused groups.

CONCLUSIONS

The increased amount of ingested amniotic fluid, or fetal "force feeding," appears responsible for enhanced growth because bovine and native rabbit amniotic fluid have only negligible differences. This study provides the first report of successful growth augmentation of a fetal rabbit runt with prenatal transamniotic fetal feeding.