This is a tough one, and you may want to consult your attorney.  Facilities have to offer a REASONABLE Accommodation.  If you can allow the pregnant worker or male worker accommodation while trying to conceive and have other workers perform that task, expecting that the worker would go back to these duties after their pregnancy/breastfeeding, then that might work.  You could get into issues, however, if other workers complain that the burden of those tasks is being placed on them.  Since you can't offer that accommodation to all pharmacy workers, then that is where you could get into issues (simply because SOMEBODY has to that job).