Why does a fetus heart bea slow?

The heart rate of a fetus typically starts around 100 beats per minute (bpm) and gradually increases throughout pregnancy. By the end of the first trimester, the fetal heart rate averages between 120 and 160 bpm.

There are a few reasons why a fetus' heart rate may be slow:

- Prematurity: Premature babies are born with immature hearts and lower heart rates. This is because their heart rate is regulated by the nervous system, which is still developing.

- Birth defects: Some birth defects, such as congenital heart defects, can cause a slow fetal heart rate. These defects can obstruct the flow of blood from the heart to the rest of the body, leading to a slower heart rate.

- Maternal factors: Certain maternal factors, such as low blood pressure or preeclampsia, can also cause a slow fetal heart rate. These conditions can reduce the blood flow to the placenta, which can in turn lead to a slower heart rate in the fetus.

- Medications: Some medications that the mother takes during pregnancy can cause a slow fetal heart rate. These include beta-blockers, calcium channel blockers, and digoxin.

If a slow fetal heart rate is detected, the doctor will typically order further testing to determine the cause. This may include an ultrasound, a Doppler test, or an echocardiogram. Treatment for a slow fetal heart rate will depend on the underlying cause.