Nobody can fire you (or terminate your grant) for getting pregnant, but they don't have to pay you while you are on maternity leave. If you are already on a T-32 and pregnant, this might be a good question for whoever at your university is administering the grant, and your PI. If you are trying to decide whether or not to try to get on a T-32, and/or trying to decide whether or not to plan on getting pregnant, I would highly advise not letting one affect the other. Pregnancy and grants are both very difficult to predict.
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