Many people use heart rate as an indicator of how hard they should be working out during pregnancy. However, there are numerous reasons why this is not the best way to know how easy or hard you should be training.

Here’s a few reasons why heart rate is not the best indicator:

Heart rate can fluctuate day to day for each person based on time of day they’re training or how hydrated they are.
Everyone’s heart rate spikes during the first and sometimes second trimester.
Based on your age your resting, target and maximum heart rate can be drastically different that another woman’s.
If you are an athlete or in good physical condition you’re heart rate will be much lower than someone who lives a sedentary lifestyle.

So what is the best way to tell how hard you should be working out?!

The Borg Rating of Perceived Exertion is the best way to to monitor exercise intensity during pregnancy

On a scale from 6-20, women should workout around 13-14 (somewhat hard). This theory is based on each woman being able to use how she feels as an accurate indicator of how hard she is working in relation to her maximum capacity. And it allows her the flexibility for each day to be different based on how she is feeling.