Temporary Uterine Circulatory Arrest as a Cause of Abnormal Fetal Development

¹ National Institute of Dental Research and Division of Research Services, National Institutes of Health, Bethesda, Maryland

An attempt was made to evaluate the effect on fetal development of a temporary hypoxia produced by an arrest of maternal blood supply to the placenta. By means of small bulldog clamps, circulation to one uterine horn was occluded in 249 gravid Sprague-Dawley rats for periods of 10-60 minutes at stages of pregnancy ranging from 7 to 17 days. The opposite horn served as a source of control fetuses. Principal findings were as follows:

Of the 871 viable experimental young that were examined on the twentieth gestational day, 26 were grossly abnormal. Thirteen of these had cleft palates, and 16 showed limb defects. One exencephaly and a generally misshapen fetus also were observed.

There were 565 macerated or resorbed experimental fetuses, the highest incidence of fetal death occurring after circulatory arrest on the thirteenth gestational day.

In the control series, there were 779 viable normal fetuses, 2 deformed young, and 73 that were macerated or resorbed.

The findings indicate that palatal development is affected by interference of circulation to the placenta, particularly when occlusion occurs on the fourteenth or fifteenth day of gestation. Similarly, a statistically significant incidence of fetal death at the longer durations of arrest is related to circulatory interference, the greatest incidence (83 per cent) being after 1 hour of occlusion on the thirteenth day.

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