Nutritional intra-amniotic therapy increases survival in a rabbit model of fetal growth restriction.

OBJECTIVE: To evaluate the perinatal effects of a prenatal therapy based on intra-amniotic nutritional supplementation in a rabbit model of intrauterine growth restriction (IUGR). METHODS: IUGR was surgically induced in pregnant rabbits at gestational day 25 by ligating 40-50% of uteroplacental vessels of each gestational sac. At the same time, modified-parenteral nutrition solution (containing glucose, amino acids and electrolytes) was injected into the amniotic sac of nearly half of the IUGR fetuses (IUGR-T group n = 106), whereas sham injections were performed in the rest of fetuses (IUGR group n = 118). A control group without IUGR induction but sham injection was also included (n = 115). Five days after the ligation procedure, a cesarean section was performed to evaluate fetal cardiac function, survival and birth weight. RESULTS: Survival was significantly improved in the IUGR fetuses that were treated with intra-amniotic nutritional supplementation as compared to non-treated IUGR animals (survival rate: controls 71% vs. IUGR 44% p = 0.003 and IUGR-T 63% vs. IUGR 44% p = 0.02), whereas, birth weight (controls mean 43g ± SD 9 vs. IUGR 36g ± SD 9 vs. IUGR-T 35g ± SD 8, p = 0.001) and fetal cardiac function were similar among the IUGR groups. CONCLUSION: Intra-amniotic injection of a modified-parenteral nutrient solution appears to be a promising therapy for reducing mortality among IUGR. These results provide an opportunity to develop new intra-amniotic nutritional strategies to reach the fetus by bypassing the placental insufficiency.

Ultrasound-Guided Intrauterine Labeling of Rat Fetuses.

AIM: To compare intra-amniotic versus fetal subcutaneous injections for selective fetal labeling in multifetal rat pregnancies. METHODS: A total of 14 pregnant rats were randomized to receive intra-amniotic injections of dyes (including Fluorescein, Indigo Carmine, or Evans Blue) or fetal subcutaneous injections (of commercial tattoo ink) both guided by ultrasound at 15-17 days of gestation. Survival, injection, and labeling success rates of both techniques were compared. RESULTS: Survival rates (84.4% for intra-amniotic injections vs. 90.9% for fetal subcutaneous injections) and injection success rates (94% for intra-amniotic injections vs. 100% for fetal subcutaneous injections) were similar among both groups. None of the neonates from the intra-amniotic injections group were labeled at birth, while 93% of the neonates from fetal subcutaneous injections group were tagged, showing a visible spot in the skin at birth. CONCLUSION: Our results suggest that ultrasound-guided fetal subcutaneous injections might be an adequate strategy for selectively labeling fetuses in multifetal pregnant animals.