A pregnant woman's heart rate?

[drystan]

My daughter-in-law is 17 and is 12 weeks pregnant and has just had her first appointment with a nurse who told her her heart rate was just 35 bpm. She has not been referred for any tests. My daughter-in-law was told that this could be due to the fact that she used to do martial arts and running, although I am skeptical of this due to the fact that she hasn't done any exercise for well over a year and half and until recently smoked and drank and she had put on quite a bit of weight before she became pregnant. I have done some research online but cant fine supporting evidence to explain this low heart rate, especially as a pregnant woman's heart rate can increase by up to 30 bpm. Am I worrying unnecessarily or should my daughter-in-law insist on some test to ensure that the health of her and her baby is not at any risks?