And while you might see pregnancy as equivalent to having a medical condition there are actually a number of fairly important differences. For example, in the modern era, pregnancy is more controllable than illness. Quite a number of people enthusiastically plan on it. Those aspects, intent and control, are important for determining who should bear the cost. The cost should not settle on an unwitting employer looking for a new hire.
Fortunately this is exactly how it's implemented in most European countries: if the employee is not working the employer doesn't pay. The (usually state run) insurer does.
Requiring businesses to pay for someone taking time to care of their children is patently stupid and unjust and there is fully justified pushback against such laws.