The Fetal Heart

The fetal heart is a lot different than a newborn heart. A fetus does not use their own lungs until they are born so they fetal heart does not pump blood through the lungs in order to collect oxygen. Just a few weeks after conception, the fetal heart takes up the majority of the fetus’ very small body. The heart resides high in the chest, but after a few more weeks will move down to its normal position in the chest cavity. The fetus’ heart begins to beat at 5 weeks gestation, at around 80-85 beats per minute. This rate increases about 3 beats per minute per day during the first month.

The Fetus Heart

When the fetus heart is first developed it resembles that of a tube. As the fetus begins to grow, so does the heart. Due to lack of room, that tube begins to bend and twist, beginning to take on the shape of a normal human heart. At this stage the heart has two separate heart chambers. Next, the heart develops two atriums and one large ventricle. The next step in development is the separation from one large ventricle into two ventricles, the left and the right. The fetus heart now has four heart chambers.

The Fetus Heart Structure

During each stage of development, the fetal heart resembles the structures of hearts similar to animal’s hearts. In the early stages when the heart looks like a tube, it is similar to a fish heart. Next when the fetus heart begins to take shape and form two chambers, it resembles a frog’s heart. After the fetal heart has developed two atriums and one large ventricle, it looks similar to a snake or turtle heart. Lastly when the fetus heart has developed all four heart chambers it has a distinguished structure of a human heart.

Fetal Heart Beat

Through development the fetal heart has some extra passages throughout the heart that differ from a human heart. A newborn’s heart has a left and right atrium that are part of the processing of pushing deoxygenated blood from the heart into the lungs, then receiving oxygenated blood from the lungs . In a fetal heart there is an opening between these two atriums called the foramen ovale, letting blood flow freely from the right atrium to the left. A newborn’s heart has a pulmonary artery, which pushes blood from the heart to the lungs and an aorta, which receives oxygenated blood from the lungs and pushes it out to the rest of the body. The fetus heart has a blood vessel, the ductus arteriosus, which connects the pulmonary artery and the aorta. After birth the ductus arteriosus will close, leaving a separated aorta and pulmonary artery.

Fetal Heart Rate

The fetal heart rate can usually be detected with a fetal ultrasound doppler as early as 8 weeks. The normal fetal heart rate is between 110 to 180 beats per minute, but can vary slights. Fluctuations can occur throughout the day due to activity level and are completely normal. Many believe that gender prediction can be done through fetal heart rate. It is said that if your baby’s heart rate is less than 140 beats per minute it’s a boy and if it’s over 140 beats per minutes it’s a girl. Unfortunately this is just an old wives tale and the only way to determine gender is through a sonogram.

As your fetus begins to develop, their heart is present from a very early stage. Through all the steps of development the heart continues to beat. Even after your baby is born, the heart continues to develop for a few weeks as it forms into a fully functioning human heart.

Author: Unique Ultrasound