A must-read for pregnant mothers: If the fetal heart rate monitoring fails, does that mean there is something wrong with the baby?

Author: Guo Yi, attending physician at Tongji University Oriental Hospital, PhD

Reviewer: Li Fang, Chief Physician, Tongji University Affiliated Oriental Hospital

Xiaolin is 36 weeks pregnant. She happily went to the hospital for a prenatal check-up. After 20 minutes of waiting, a long fetal heart rate monitoring paper was printed out. Xiaolin handed this "report card" to the doctor, but the doctor frowned and said, "The fetal heart rate monitoring failed." Xiaolin felt very strange. The B-ultrasound result was obviously normal. What did it mean that the fetal heart rate monitoring failed? Did she suspect that the baby in her belly had some disease? The doctor told Xiaolin not to worry too much and asked her if she was hungry. She asked her to eat something first, breathe oxygen while waiting in line, and do it again in 1 hour. 1 hour later, when Xiaolin finished the fetal heart rate monitoring and handed the test results to the doctor worriedly, the doctor said, "Congratulations, the fetal heart rate monitoring passed." Xiaolin asked doubtfully, "Doctor, is there really nothing wrong with the baby?"

This situation is encountered almost every day in the obstetric clinic. Many pregnant mothers need to extend the fetal heart monitoring time, recheck or hospitalize for observation because the fetal heart monitoring is not up to standard, and some even terminate the pregnancy early.

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But in fact, many pregnant mothers do not know what the two lines on the fetal heart rate monitoring paper that fluctuate like Arabic characters actually mean. Is this another "language" that only doctors understand?

It's true! Fetal heart rate monitoring is another "medical language" that all obstetricians can understand. The two simple curves contain a lot of knowledge. It not only "tells" the baby's fetal heart rate changes, fetal movements, and whether there is possible hypoxia, but also "tells" the pregnant mother's uterine contractions. Therefore, fetal heart rate monitoring is a "good helper" for obstetricians and a powerful weapon to reduce the incidence of adverse maternal outcomes.

In response to the doubts of Xiaolin and other pregnant mothers who have similar experiences, we would like to give a brief explanation here.

1.What is fetal heart rate monitoring?

Fetal heart rate monitoring, referred to as "fetal monitoring", is divided into antenatal fetal monitoring and intrapartum fetal monitoring according to whether labor is imminent. Most of the routine fetal heart rate monitoring performed by pregnant mothers in obstetric clinics is antenatal fetal monitoring without regular uterine contractions and before labor. This is one of the must-do examinations for every pregnant mother with a gestational age of more than 34 weeks during weekly prenatal check-ups. The monitoring time is generally 20 minutes. When doing fetal monitoring, two probes will be tied to the pregnant mother's belly. One is used to feel the contraction intensity of the pregnant mother's uterus, called the "uterine cavity pressure probe"; the other is used to listen to the baby's heartbeat, called the "fetal heart rate probe". During the process of fetal heart rate monitoring, pregnant mothers can hear the sound of "dong dong dong", which is the baby's heartbeat detected by the fetal heart rate probe. At this time, pregnant mothers can relax and breathe fresh air. They do not need to keep the same posture all the time. They can sit or lie on their side (such as left side lying position). If the pregnant mother gently pats her belly at this time, or plays a piece of music that the baby likes, she can feel the baby responding in the abdomen through fetal movement and a short fetal heart rate acceleration.

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2. If the fetal heart rate monitoring fails, does that mean there is something wrong with the baby?

Not necessarily. The results of fetal heart monitoring can be divided into normal (responsive), atypical (suspicious) and abnormal (unresponsive). In the 20 minutes of fetal heart monitoring, under normal circumstances, the baseline of the fetal heart rate is 110-160 beats/minute. When the fetus moves, the fetal heart rate will fluctuate from the baseline and accelerate intermittently. The acceleration is manifested as the line representing the fetal heart rate will fluctuate upward to a certain extent. If there is neither acceleration nor a significant deceleration in 20 minutes, the doctor will generally extend the monitoring time of the pregnant mother or review it later. At this time, the fetal heart monitoring is temporarily regarded as "unsatisfactory" by the doctor. However, the reason for this result may also be that the baby is sleeping, or the baby is hungry and unwilling to move, or the pregnant mother suffers from temporary hypoxia due to wearing a mask for a long time. Therefore, in response to this situation, we have the following tips to help pregnant mothers.

(1) If the baby is sleeping, usually the fetal heart rate monitoring time can be extended to 40 minutes to see changes in fetal heart rate acceleration, because the baby's sleeping and awake times usually alternate in a short period of time.

(2) We can play some lively music. The sound stimulation can induce the fetal heart rate to accelerate. Many babies like to dance to the music.

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(3) Pregnant mothers can change their body position to a semi-recumbent or side-lying position. The baby may suddenly have more space to stretch or be relieved of pressure and become more active.

(4) If the baby is hungry, he will move less, so pregnant mothers should not be on an empty stomach before fetal heart monitoring. If conditions permit, you can bring some snacks with you. However, pregnant mothers with diabetes must pay attention to blood sugar control.

(5) In order to protect themselves and their babies, many pregnant mothers wear masks when they go out, but they must be careful not to cause hypoxia, because the baby's nervous system development requires sufficient oxygen.

(6) Pregnant mothers should make sure to get enough rest, eat properly, and avoid staying up late or overexerting themselves.

If pregnant mothers have achieved the above points, but the qualified acceleration is still less than 2 times within 40-80 minutes of fetal heart monitoring, or there are problems with the baseline or baseline variation, or there is a deceleration within 1 minute, then the doctor will judge it as "suspicious fetal monitoring", that is, "atypical fetal monitoring". At this time, many doctors will let pregnant mothers be hospitalized for observation to further rule out ischemia, hypoxia, acidosis or other causes of nervous system damage or abnormal heart function. At this time, pregnant mothers must cooperate with doctors, closely monitor and further examine, which is also responsible for themselves and their babies.

When the fetal heart rate monitoring shows less than 2 qualified accelerations within 80 minutes, bradycardia, tachycardia, long-term deceleration and other serious fetal heart problems, the doctor will judge it as "abnormal fetal monitoring", that is, "unresponsive fetal monitoring". At this time, the fetus is likely to be in danger, and pregnant mothers need to actively cooperate with doctors for treatment and terminate the pregnancy early if necessary.

3. How do pregnant mothers monitor themselves?

Fetal heart rate monitoring can help doctors detect abnormal fetal conditions or fetal hypoxia caused by poor uterine-placental circulation, but how should pregnant mothers monitor themselves and detect abnormalities at home?

In fact, after 28 weeks, pregnant mothers can feel fetal movement. Every pregnant mother needs to learn to count fetal movements by herself, especially those who have had "suspicious fetal monitoring" or fetal heart monitoring failures. It is recommended that they do a strict fetal movement counting at home. Now, let me teach you how to observe fetal movement!

Pregnant mothers can count fetal movements for one hour at fixed times in the morning, noon and evening every day. The sum of the three values ​​multiplied by 4 can be regarded as the number of fetal movements in 12 hours.

Normal fetal movements are 3 to 5 times per hour, and generally 30 to 40 times in 12 hours.

(2) Fetal movements less than 20 times in 12 hours are abnormal and you should go to the hospital for treatment. Fewer than 10 times may put the fetus in danger.

(3) If the fetal movements are frequent and non-stop over a period of time, that is, the number of fetal movements exceeds 50% of the daily number, it may also be a sign of hypoxia.

It is important to emphasize that pregnant mothers must have regular prenatal checkups, cooperate with doctors, and communicate with doctors more often. In different situations, such as before and during delivery, fetal heart monitoring will have different changes and meanings. After all, fetal heart monitoring is just a tool, and it is your obstetrician who really protects you and your baby!

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