The righting reflex from a supine to a prone position in the guinea pig fetus.

The aim of this study was to examine the righting reflex from a supine to a prone position in the albino guinea pig fetus. Ultrasound examinations of one-fetus gestations were performed in the period from the 31st to the 66th day of gestation. The experimental and control group each encompassed 6 fetuses. Fetuses were brought into supine positions relative to the gravity vector by manipulating the pregnant females into the appropriate positions. The control group received 15 mg/kg of diazepam intraperitoneally before the examination to show whether changes in fetal position occurred as the result of passive rotation. In the experimental group, each fetus was examined every other day (summary results: absent 69 times, prone position 10 times, lateral position 29 times). In the control group, each fetus was examined every five days (summary results: absent 42 times). The absence of the righting reflex in the control group was statistically significant (chi(2) = 18.66, df = 1, p = 0.000, p < 0.05). The experimental group fetuses assumed a prone position more frequently in the period from the 51st to the 66th day of gestation than in the period from the 31st to the 50th day of gestation (chi(2) = 4.17, df = 1, p = 0.0412, p < 0.05), suggesting maturation of the righting reflex.