What is the normal value of umbilical cord blood flow at 30 weeks of pregnancy?

When a woman becomes pregnant, she pays great attention to the baby in her belly. She will observe the baby through various examinations to see whether the baby is in good physical condition, what stage of development it has reached, and so on. Umbilical cord blood flow is a very important observation value, because the baby and the pregnant woman are connected through the umbilical cord. So what is the normal value of umbilical cord blood flow at 30 weeks of pregnancy? Let me introduce it to you below.

In normal pregnancy, the S/D and RI values ​​of the fetus tend to decrease as the pregnancy progresses. In particular, the change in the S/D value is an important indicator of whether the fetal development is normal. The first stage: If the S/D and RI values ​​increase from 26 to 28 weeks of pregnancy (after 28 weeks, the S/D should be less than 3 and the RI should be less than 0.8), the main considerations are:

(1) Fetal malformation: Fetal congenital diseases are closely related to umbilical artery resistance and should be further examined by B-ultrasound.

(2) Umbilical cord abnormality: When the umbilical cord is entangled, too long or too short, or too thin, affecting the placental circulation, the blood flow impedance index will be abnormal. If the S/D value is higher than the normal value, and B-ultrasound shows abnormal conditions such as the umbilical cord around the neck, the patient should be closely observed according to the stage of pregnancy.

(3) Poor placental function: Pathological changes in the placenta can lead to a decrease in placental volume, a decrease in the total cross-sectional area of ​​effective blood vessels, increased blood flow resistance, and a decrease in blood perfusion.

(4) Intrauterine Growth Retardation (IUGR): There are many reasons for pregnant women to have IUGR. In addition to genetic nutrition, harmful contact, malformation, virus and other factors, the proportion of IUGR caused by pregnancy appendages such as the placenta is increasing, which is manifested by increased S/D and RI values. The second stage: monitoring after 36-37 weeks, the umbilical artery blood flow impedance is divided into three levels. Level 1: S/D value 3.0, but 4.0 will lead to poor perinatal prognosis. The third stage: umbilical artery impedance index during delivery: When a normal pregnant woman is about to give birth, the S/D value does not change significantly. If the index is abnormal, it indicates a poor perinatal prognosis. If the umbilical blood flow abnormality is diagnosed, it is best to count the fetal movements every day to monitor the fetal condition. If the umbilical blood flow abnormality is not very serious, it is recommended to take the left side lying position. If there is no improvement, oxygen therapy is required if necessary.

The role of umbilical cord blood flow

The purpose of checking the umbilical cord blood flow is to determine the development of the fetus in the uterus, such as whether there is intrauterine growth retardation, whether there is a tendency to develop pregnancy-induced hypertension syndrome, and whether there is intrauterine fetal hypoxia. Umbilical cord blood flow may sometimes show abnormalities due to fetal chromosomal abnormalities, congenital malformations, etc. Abnormal umbilical cord blood flow may also be related to developmental defects and histological abnormalities of the placenta. The normal value is related to the number of weeks of pregnancy. There are three main items, with the S/D value as the main indicator. The normal value is usually an S/D value of less than or equal to 3.0 in the late pregnancy.