I cannot lift heavy packages at work because I am pregnant. My coworkers constantly complain about this and call me a slacker, but I guess I just have to put up with it.

Not necessarily.

Human rights laws in Canada protect against discrimination on the basis of gender and family status. As a result, your employer must ensure that you do not feel unwelcome in your workplace and are not harassed because you are pregnant.

You have a right to speak to your employer about your concerns, and your employer is required to take appropriate action. Sometimes it can be difficult for an employer to figure out how to make a difference in these situations. The Alberta Human Rights Commission has education programs and consultation services to help with workplace discrimination. Either you or your employer can ask the Alberta Human Rights Commission for this help.

If your employer still will not take any action, you can make a formal complaint to the Alberta Human Rights Commission.