Pregnancy, tumor growth, and liver regeneration.

Summary Partial hepatectomy in the pregnant rat caused death of many fetuses and impaired growth of surviving fetuses. This damaging effect upon the fetus was not alleviated by feeding a high-protein diet nor by administration of estrone and progesterone. In the pregnant rat, liver regeneration was enhanced at 12 days but not at 4 days after partial hepatectomy. The growth of three transplanted tumors (Walker 256, lymphosarcoma, hepatoma) was not influenced by pregnancy, regardless of whether the experiment was designed to yield small or large tumors. The growth of large Walker tumors had but a slight damaging effect on the fetuses, whereas even small hepatomas caused fetal death or fetal resorption. This could be owing to a specific quality of this hepatoma or to a particular vulnerability of the fetus in the A × C rat, in which this tumor is grown.