Maya Angelou recites her poem 'On the Pulse of Morning' at the inauguration of President Bill Clinton on January 20, 1993.
Pregnant women could also go for a swim at a swimming pool, but it can also be risky in some circumstances. The chemicals used in swimming pools can be dangerous for moms-to-be and their babies, if too much is being added to the water, but normal levels of chlorine are generally OK unless the water is ingested.
1 (Even ocean swimming is fine; just make sure the waves don't knock you down.)  Wear breathable fabrics so you won't sweat; this will keep you cooler and help prevent heat rash that can develop under your breasts and abdomen, a common problem for pregnant women.