Obstetricians use a special Doppler instrument between the 10th and 20th weeks of pregnancy to listen to the fetal heartbeat. After the 20th week, listen to the heartbeat at home with an ordinary stethoscope. This can be reassuring, especially before the baby's movements become vigorous. At any time, hearing the evidence of the new life within is a special bonding experience.
After 20 weeks, the mother should lie on her back in a comfortable position where there is little noise.
Palpate the abdomen over the uterus and look for the baby's back. It usually feels like a firm area within the uterus. The baby's heartbeat can be heard most clearly through his back, the Dr.Spock website states. According to the book, "The Father's Almanac," by the seventh month babies usually lie upside down on their backs and to the left of the abdominal mid-line, so from week 28 look for the back lower than and to the left of the navel.
Put on the stethoscope by inserting the earpieces and place the bell or concave side of the stethoscope on the abdomen over the baby's back.
Listen for the heartbeat. It should be between 120 and 160 beats a minute. Use the second hand on the watch or a stopwatch to time the beats per minute. If the heartbeats are 100 per minute or below, they are the mother's heartbeat, according to the Dr.Spock website. In that case, reposition the stethoscope to another spot and listen again.
Take the mother's pulse while listening to the mother's or baby's heartbeat if in any doubt about which one it is. Compare the pulse rhythm with the observed heartbeat. If they match, it is the mother's heartbeat.
It is often difficult to hear the heartbeat with a stethoscope around 20 weeks, so don't be overly concerned if it isn't easily located. Try again a little later in the pregnancy. It gets easier to detect as the baby grows. Factors such as the position of the baby, the position of the placenta and whether the mother is overweight all influence how well the fetal heartbeats can be heard. The loudness of the heartbeat is influenced by many things. A faintly heard fetal heartbeat has to do with the quality of sound transmittal rather than how strongly the heart is beating. Ask the obstetrician to teach you how to use the stethoscope during a scheduled visit if you are having difficulties using it.