Women who are pregnant are considered at an increased risk of pretty much everything, in part because pregnancy is a stress to your system. Also the, studying pregnant women and the effects of diseases or drugs is ethically more challenging, the data collected is either incidentally collected or collected well after other studies have concluded and given a factor of safety... so the sample size of any study is almost always so much smaller that it is necessarily more error prone because that any blip in the data becomes more significant... and pregnancy always has something that causes a blip somewhere along the line.
This abjectly false and incorrect. Pregnancy is a normal physiological state — there is not increased risk to the mom with just about everything. In the first trimester there is high risk of teratogenesis with exogenous medication administrations. There are some disease states that are deleterious in pregnancy, however, you are painting with far too broad of a brush with your statements.