If you're a very good tennis player, it probably is safe.
But the American College of Obstetricians and Gynecologists recommends avoiding sports with a high likelihood for contact or falling — and that includes tennis.
One of the concerns with racquet sports such as tennis is that they often involve rapid changes in direction.
With the changes in your center of gravity during pregnancy, these rapid twists and turns could make you more prone to falling.
If you fall you could start bleeding if the placenta detaches from the uterus, or you could begin having contractions.
Either event can place the fetus at risk of premature delivery.
Bleaching teeth during pregnancy
Vacation at high altitude during pregnancy
Swimming in a chlorinated pool during pregnancy
Riding the bumper cars at an amusement park during pregnancy
Riding horseback during pregnancy
Moving furniture during pregnancy
Jogging during pregnancy
Ice-skate or Roller blade during pregnancy
Go to a rock concert during pregnancy
Skiing during pregnancy