My wife is 36 weeks pregnant and from 1 week her heartbeat is becoming fast several times during day. what could be the reasons and how to avoid it?

Palpitations: it is normal in pregnancy for a womans heart rate to get a little bit faster however this should not be a sudden occurrence within a week nor should a woman have a palpitation that she can feel or that you do. if she has any associated symptoms of chest pain or shortness of breath, she should see a doctor, and get a EKG and monitoring.