Pregnant cats taking anthelmintic drugs will affect the fetus and easily cause fetal malformation. Therefore, pregnant cats should not take anthelmintic drugs to avoid affecting the fetus in the belly. If the pregnant cat at home has parasites in its belly, it is most dangerous. It is best not to deworm the kitten, but to wait until the kitten is one month old before deworming the kitten internally and externally, so that both the big cat and the kitten will be healthy.