The US Supreme Court is currently hearing arguments on a case where a woman who works for UPS is suing for the right to receive the same level of treatment by their employer that a UPS driver who has their driver's license suspended as a result of being found guilty of driving under the influence of alcohol (DUI)...
Namely, that instead of being fired, or being suspended without pay until such time as their driver's license is reinstated, UPS employees are given a transfer to a job that does not require them to drive.
If an alcoholic can be given an accommodation at work that allows them to continue working at the level that they are capable of doing, then a pregnant woman should be give the same consideration and allowed to work a light duty job such as clerical work with FULL pay.