Pedialyte is fine to drink during pregnancy when consumed in moderation.
The drink's main ingredients are water, sugar, and electrolytes, and it can be a fast way to promote hydration and replenish electrolytes after a particularly hot, sweaty summer day or while recovering from a virus or bout of morning sickness.
Drinking Pedialyte as needed in one of these circumstances is unlikely to be harmful, but keep in mind that it also contains some additives that may not be great to consume in high quantities during pregnancy. One common additive is sugar, which is beneficial to consume only in moderation, whether you're pregnant or not, and the use of sugar-free alternatives have not been as thoroughly investigated during pregnancy. Bottom line: don’t go stacking your drink cupboard with Pedialyte just yet.