Your employer doesn't have to offer sick leave, but you still have a right to take time off when you're really ill. The federal Family and Medical Leave Act, for example, gives you the right to stay home on unpaid leave if you have a serious health problem, including complications from pregnancy. Some employers, despite the law, do retaliate against sick employees.
Sick Leave
If your company offers sick leave, it can legally require you to give advance notice whenever possible -- for example, if you have surgery scheduled. The company can also make you bring in a doctor's note if you have to take unplanned leave. If you take sick leave and don't follow company procedure, your boss may have grounds to penalize you. If you follow the rules or you have to take leave in an emergency, punishing you would be crossing the line.
FMLA
If you have what the FMLA considers a serious health condition, you're legally entitled to take several weeks off. Serious conditions include anything that requires an overnight hospital stay, trips for kidney dialysis or being unable to work because of pregnancy. Your employer can require your doctor to fill out a certification form confirming that you're too sick to work. As long as you follow FMLA requirements, your employer has to reinstate you when you come back.
ADA
The Americans with Disabilities Act kicks in when you've become too disabled by illness or injury to keep working without special help. The ADA requires your company make "reasonable accommodation" to let you keep your job or get an equivalent position. What's reasonable depends on the situation. If you have to leave work for physical therapy or you need special equipment to compensate for becoming deaf, in many cases your company has to provide it.
Retaliation
Even if your company doesn't intend to punish you for staying home sick, it may make a mistake. Your boss may decide that no matter what your doctor says, your health problems aren't FMLA-serious. The company may take you back but in a lower position with less pay and benefits. You can try to work through the company's HR procedure for resolving complaints, but you may end up having to talk to a lawyer.
