Never! My last workout was 2 days before each of my kids were born. I ran (till about 20 weeks) walked, swam laps, did the elliptical, and lifted weights throughout my pregnancies.
I had really easy, uncomplicated vaginal deliveries and was back in the gym within 2-3 weeks of giving birth. I could not wait to start working out again! ETA: I started walking daily with both kids just a few days after delivery. After DD was born, I was running within 2 weeks, and ran a 5K when she was 6 weeks old exactly.
mommy to DS who is 9
DD who is 6
and my girl in heaven