Effect of hypoxia on fetal rabbit gastrointestinal motility

During fetal hypoxic stress, blood flow is shunted from nonvital to life-preserving organs, including the heart and brain. Reduced oxygen to the small intestine (SI) induces mucosal injury and may contribute to neonatal necrotizing enterocolitis (NEC). As little is known about the relationship between fetal hypoxia and GI motility, we assessed potential effects in a rabbit model. Twenty-one pregnant rabbits were randomized into two groups, hypoxia (Hyp) and control (Cont). Seven litters were studied at Gestational Days 24, 27, and 30 of their normal 31-day gestation. Under ultrasound guidance each fetal stomach was percutaneously accessed. Fluorescein, labeled with color-coded microspheres for precise fetal identification, was injected. Hyp rabbits breathed 11% oxygen for 1 h after recovery from anesthesia; Cont rabbits breathed room air. Two hours after injection, fetuses were delivered and weighed. The SI was harvested, the length recorded, and the distance fluorescein traveled measured by UV light optical density. Results were analyzed by the unpaired Student test. All injected fetuses (N = 167) survived. The length fluorescein traveled was shorter in Hyp than Cont at all gestational days studied (P < 0.01): Day 24, Hyp = 6.7 +/- 2.0 vs Cont = 8.4 +/- 2.1 cm; Day 27, Hyp = 10.1 +/- 2.9 vs Cont = 19.1 +/- 4.4 cm; and Day 30, Hyp = 16.8 +/- 3.5 vs Cont = 23.1 +/- 5.2 cm. The percentage motility, defined as the length of fluorescein travel divided by total SI length, was also significantly less at all gestational days. Fetal rabbit GI motility was significantly decreased by maternal hypoxia during the last third of gestation. Hypoxia-induced reduction in GI motility may contribute to neonatal NEC.