The heartbeat is one of the first signs that a pregnancy is viable and once it is detected the chances of a successful pregnancy are considerably increased. It is therefore no surprise that pregnant women (and undoubtedly their partners) cannot wait to have an ultrasound scan to show the heartbeat. In addition, it is one of the most memorable moments of your pregnancy – the first time you saw and heard your baby’s heart beating – that creates a great emotional bond between you and your baby and makes you fall in love in an instant.
Commonly the first ultrasound scan doesn’t take place until week 12 of your pregnancy when the risk of miscarriage reduces. However, in complicated pregnancies, when there have been previous miscarriages or if the baby was conceived through assisted conception such as IVF early pregnancy scans can be carried out.
The stage when a heartbeat can be detected depends on the type of ultrasound.
The most common ultrasound is the external ultrasound. The earliest a heartbeat can usually be detected using an external ultrasound is at 7 to 8 weeks in the pregnancy. At this stage the fetal age is 5 - 6 weeks as the first two weeks of pregnancy are the time from the start of your last period until conception and therefore before the embryo started to develop.
The reasons that doctors are often reluctant to carry out such an early scan is that a heartbeat might not be detected yet even though there is no problem with the pregnancy. The time of conception is not always known exactly and the fetus could be slightly younger and not sufficiently developed yet to has a working fetal pole which in turn develops into a heart. Not finding a heartbeat can be very distressing for a pregnant woman and
However, if an early pregnancy scan is carried out this usually happens through in internal or vaginal ultrasound. Using this method earlier and more accurate readings can be obtained. Using this method the fetal pole or even a fetal heart beat can be detected by week 6 or in other words a fetal age of 4 weeks. The heartbeat if detected can be seen as a regular flutter on screen.
Even with a vaginal scan and known date of conception (for example when IVF took place) it is possible that the heart cannot be detected, but there is nothing to worry about and the pregnancy will carry on without complications. In this case a further scan usually takes place in another 3 – 7 days to ensure that the fetus just hadn’t sufficiently developed at the previous scan.
Seeing and hearing your baby’s heartbeat is a wonderful experience and understandably expectant mothers are impatient to witness this proof of their baby’s existence. However, an early pregnancy scan can also create unnecessary distress as a heartbeat might not yet be detected maybe due to incorrect assumption of the conception date.