In this 2D ultrasound, the baby's head is to the left, with the arms not visible, although the knee and lower leg can be seen. At this stage, details of the brain developing under the skull are becoming much more apparent.
At this stage of pregnancy, your doctor may be able to hear your baby's heartbeat using a handheld Doppler ultrasound machine. Because ultrasound waves do not travel well in air, gel is applied to the end of the probe or "transducer" as it is placed on your abdomen. This then detects the heartbeat and converts it into a sound that we can hear.
It's quite easy to distinguish your baby's heartbeat from your own since it beats almost twice as fast. However, your baby's heart rate peaked around five weeks ago and, since then, has slowed down as the nerves controlling the heart's rhythm have matured.
During the second half of pregnancy, the range of the heartbeat is between 120 and 160 beats per minute and will be responsive to many stimuli, as well as to your baby's activity.
The baby's heart rate is not an indication of gender.
A study in the mid-1990s, using over 10,000 measurements, dispelled the theory that the speed of a baby's heartbeat predicted whether it would be a boy or a girl.
Doctor: Handheld ultrasound Doppler devices, which allow parents-to-be to listen to the fetal heartbeat at home, are currently sold over the counter in the US. Parents are told they can listen to their baby "in complete safety as early as 10 weeks of pregnancy" and "any time they want," implying there is no limit on frequency of exposure.
However, there has been no research into the effects of frequent scanning, which would be more than the baby receives during prenatal care. A Doppler is not a toy and using it in this way is an unnecessary risk.
Midwife: Using your own Doppler may help reassure you if you are very anxious about your baby's well-being, but it is just as likely to have the opposite effect if you can't pick up the heartbeat. Identifying different sounds takes practice and if you have difficulty finding the heartbeat (this happens to midwives, too!), it could be distressing. If you're worried about your baby for any reason, help and advice is only a phone call away.
Mom: I used a Doppler because I am a worrier and it really gave me peace of mind. I didn't use it very often and only when there was a good reason to. For example, at one stage of my pregnancy, I had an episode of bleeding and clots. After this, I was very worried about my baby's health and hearing his heartbeat really helped to calm me down, so it had benefits for the baby, too. I don't think a Doppler is a substitute for medical advice but it's a useful addition.
Excerpted from Pregnancy Day by Day.
Copyright ©2009 Dorling Kindersley Limited.
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