One of the ego's sole missions is to try to control outcomes, so it thinks that if it can just answer this one question, it will successfully avoid a failure, which ego interprets as a mistake. And because ego doesn't hold the mindset that failures and mistakes are how we learn but instead believes that they're measures of our self-worth, it has no tolerance for mistakes.
The 'What Ifs' of motherhood can boil down to instinctual anxiety about our children's safety, the drive to protect, and awareness that we can't stave off every hazard. Anxiety is often considered the enemy, something to be avoided. However, in many ways, maternal predisposition to anxiety can be seen as a positive, adaptive process.