Paula Radcliffe, the woman who won the New York City Marathon less than ten months after giving birth to her daughter, is pregnant again with Baby #2 -- and she's running 14 miles a day to train for the 2012 Olympics.

During her first pregnancy, Radcliffe also trained rigorously. She said that safety was her top priority, and her OB/GYN closely monitored her throughout each trimester, giving her monthly ultrasounds from the fifth month on. Under doctor's orders, Radcliffe never allowed her heart rate to rise above 160 beats per minute while running.

Radcliffe is now five months pregnant, and has gained 13 pounds so far.

We asked Dr. Suzanne Gilberg-Lenz about training while pregnant. Here's what she had to say:

Dr. Suzanne Gilberg-Lenz: Exercise and fitness are encouraged during pregnancy. Regular, moderate exercise is known to decrease fatigue and nausea during the first trimester, and to increase stamina, flexibility and potentially endurance in later trimesters -- possibly even during labor!

Exercise is best started well before pregnancy as part of any woman's healthy lifestyle. But even for fit women, the types of exercise that are safe can change during the course of pregnancy. As a pregnancy proceeds, balance can become an issue; aerobic exercise that is lower impact -- such as walking, gym machines, swimming, stationary cycling, yoga or strength training -- is generally safe.

To be clear: No-nos include downhill skiing, contact sports, surfing, horseback riding, skateboarding and scuba diving. Obviously, most X-Games athletes would probably need to take a break. I usually advise my patients, "If you fall, will you freak out? Then don't do it!"

Do YOU think a pregnant woman should run 14 miles a day?