I don't know what to tell you. In the 1980s, the Supreme Court determined that such matters fell within the area of labour relations and were therefore under the shared jurisdiction of the federal and provincial governments. That is why the preventive withdrawal from the workplace of a worker who is pregnant or nursing, in Quebec, does not apply to federally regulated employees. In response to your question about whether federal legislation should incorporate specific conditions, I would say that the Supreme Court's decision would likely be the same. In other words, preventive withdrawal could apply to federal employees, but could not be imposed on the provinces.
On April 4th, 2017. See this statement in context.