Is it permissible for a pregnant woman to take an antispasmodic medication containing animal gelatin of unknown origin, given the absence of a safe alternative during pregnancy?

The Shari'ah commands and encourages medical treatment. The default rule for things is permissibility. Therefore, there is no objection to treating with the prescribed medicine unless it is known with certainty that it contains something prohibited. If no other medicine can be taken during pregnancy besides the prohibited one, and the pregnant woman is compelled to take it due to her suffering, then there is no objection to its use, because necessities render forbidden things permissible, and because the benefit of well-being is more complete than the benefit of avoiding impurities.