Starting at week 5 the fetal heart will accelerate at a rate of 3.3 beats per day for the next month.

The fetal heart begins to beat at approximately the same rate as the mothers, which is 80 to 85 beats per minute.

Fetal heart rates for weeks 5 to 9, assuming a starting rate of 80 heart beats per minute:

• Week 5 starts at 80 and ends at 103 beats per minute
• Week 6 starts at 103 and ends at 126 beats per minute
• Week 7 starts at 126 and ends at 149 beats per minute
• Week 8 starts at 149 and ends at 172 beats per minute
• Week 9 the fetal heartbeat tends to beat within a range of 155 to 195 beats per minute.

The fetal heart rate will begin to decrease and generally will fall within the range of 120 to 160 beats per minute by week 12