A heartbeat is a two-part pumping action that takes about a second. As blood collects in the upper chambers (the right and left atria), the heart's natural pacemaker (the SA node) sends out an electrical signal that causes the atria to contract. A normal heart rate for adults is typically 60 to 100 beats per minute. A heart rate that is slower than 60 beats per minute is considered bradycardia ("slow heart") and a rate that is faster than 100 beats per minutes is termed tachycardia ("fast heart").

As for the baby, the average fetal heart rate is between 110 and 160 beats per minute. It can vary by 5 to 25 beats per minute. The fetal heart rate may change as your baby responds to conditions in your uterus. A fetal heartbeat may first be detected by a vaginal ultrasound as early as 5 1/2 to 6 weeks after gestation. That's when a fetal pole, the first visible sign of a developing embryo, can sometimes be seen. But between 6 1/2 to 7 weeks after gestation, a heartbeat can be better assessed.

Heartbeat for a baby boy or girl?

If the fetal heart rate is under 140 beats per minute (BPM), it's a boy. False. A baby girl's heart rate is usually faster than a boy's, but only after the onset of labor. There's no difference between fetal heart rates for boys and girls, but the rate does vary with the age of the fetus. If your baby's heart rate averages in the 110 to low 130s range, the thought is that it's more likely a boy, and if it's in the mid 140s to 160 range, it's more likely a girl. Mid-130s to 140s is unpredictable -- and where a lot of heart rates fall. If it is closer to 5 to 6 weeks, then not seeing a heartbeat is totally different. If you are measuring 6 weeks or less, then you just need to wait a week and recheck that the baby has grown and a heartbeat can be seen.

Before about week 8 of pregnancy, a doctor may refer to the fetus as an embryo. Blood tests to screen for certain conditions can tell us gender after nine weeks. At 12 weeks, we may be able to use ultrasound to determine gender based on the angle of the genital tubercle.

If you are past seven weeks pregnant, seeing no heartbeat may be a sign of miscarriage. But there are many exceptions to the "heartbeat by seven weeks" rule. You've likely heard of people who were certain they had miscarried or were not pregnant, and then went on to have a normal pregnancy.

Can stress cause fetal heartbeat to stop?

Stress-related changes in a pregnant woman's heart rate and blood pressure, along with chronic anxiety, can affect the heart rate of her developing fetus, a new study concludes. Most women first hear their baby's heartbeat during a routine checkup that uses the fetal Doppler early in their pregnancy.

Myths vs. Facts: Signs You're Having a Baby Girl

• Carrying high.
• Carrying around middle.
• Faster fetal heart rate.
• Craving sweets.
• Breakouts.
• Morning sickness.
• Mood swings.
• The truth.

Old Wives' Tales Say You're Having a Boy If...

• You're carrying low.
• You're only putting on pounds around your belly.
• Your partner isn't gaining weight.
• Your skin is clear and glowing.
• Your morning sickness isn't that bad.
• Your urine is a dull yellow.
• Your feet are always cold.
• Your baby's heart rate is low.

If you're ready to have a baby, you likely have lots of questions.

'Happiness is hearing your baby's heartbeat for the very first time.'