What Are the Causes of Fetal Heart Rate Decrease in the Ninth Month?
The causes of a decreased fetal heart rate in the ninth month are generally similar to those in earlier stages of pregnancy. There are no specific reasons that pertain solely to the ninth month; instead, there are common factors that can lead to a decrease in fetal heart rate. A fetal heart rate is considered weak if it falls below 110 beats per minute. In some uncomplicated instances, this reduction may be temporary and resolve without medical intervention.
Some of the common factors that can contribute to a reduced fetal heart rate in the ninth month include:
- Congenital defects in the fetal circulatory system.
- Certain stages of the fetal sleep cycle, where the decrease in heart rate may be minor.
- The use of specific medications by the pregnant woman, such as:
- Opioid painkillers.
- Magnesium sulfate.
- Neurological disorders in the fetus.
- Reduced blood flow or oxygenation to the fetus.
- Factors related to the birth process, such as:
- Maternal hypotension due to anesthesia during delivery.
- Compression or prolapse of the umbilical cord.
- Rapid uterine contractions.
- Uterine rupture.
- Placental abruption.
Fetal Heart Rate Decrease Due to Maternal Health Issues
Several health disorders experienced by the pregnant woman can result in a decreased fetal heart rate. These include:
Maternal Hypoglycemia
Research has indicated a correlation between low blood sugar levels in pregnant women and a decrease in fetal heart rate. Physicians have observed that normalization of blood sugar levels often leads to the restoration of the fetus’s heart rate, underscoring the importance of regular monitoring of blood glucose in women prone to hypoglycemia during pregnancy.
Maternal Hypothermia
While the link between low maternal body temperature and decreased fetal heart rate has not been entirely clarified, a study conducted on pregnant women with hypothermia has confirmed this connection. The research demonstrated a return to normal fetal heart rate following the restoration of the mother’s body temperature, and the findings were published in the journal Obstetrics & Gynecology in 2020.
Maternal Hypotension
Low blood pressure in a pregnant woman can lead to diminished blood flow and oxygen reaching the fetus, which consequently results in a decreased heart rate. Typically, the fetal heart rate rebounds once the mother’s blood pressure returns to normal levels.
Fetal Heart Rate Decrease Due to Fetal Health Issues
Not all cases of decreased fetal heart rate are linked to maternal health problems; some can be associated with health disorders affecting the fetus. Examples include:
Congenital Heart Defects
A reduced fetal heart rate may be attributable to an underlying congenital heart defect, which is among the most common malformations during fetal development. It is advisable to conduct a fetal echocardiogram if a decrease in the fetal heart rate is detected.
Umbilical Cord Compression
Compression of the umbilical cord around the fetus’s neck can lead to decreased heart rate and may result in the following complications:
- Insufficient blood flow to the fetus.
- Decreased blood volume in the fetus.
- Fetal acidosis.
- Fetal anemia.
Intrauterine Hypoxia
The fetal brain responds to a decrease in oxygen levels by slowing down the heart rate and constricting peripheral blood vessels; this reaction is mediated by the carotid body’s chemical reflex and controlled via the vagus nerve.
Are There Symptoms of Fetal Heart Rate Decrease in the Ninth Month?
A pregnant woman may find it challenging to perceive a decrease in fetal heart rate since there may be no apparent symptoms. However, some women may notice signs indicating potential issues with fetal heart rate, including:
- Changes in fetal movements.
- Intense contractions coupled with lower back pain.
- Vaginal bleeding.
Article Summary
A decrease in fetal heart rate during the ninth month represents a medical complication that necessitates close monitoring of fetal health to take appropriate measures to restore normal heart rate and ensure the well-being of the fetus. In some cases, this decrease may be temporary, such as that caused by maternal hypothermia or hypotension, returning to normal once the cause is addressed. Conversely, it may stem from a serious fetal health issue requiring urgent medical attention.