What are the normal values for umbilical artery blood flow PI, RI, and S/D?

The normal values of PI, RI, and S/D in umbilical blood flow differ according to the gestational week. Generally, the normal range is 0.7-1.5 during the first trimester; 1.2-3.9 during the second trimester; and 1.4-3.6 during the third trimester. These values are crucial indicators for assessing fetal health and can help doctors determine whether the fetus is receiving adequate nutrition and oxygen in the uterus.

1. First Trimester - In the early stages of pregnancy, when the placenta is not fully formed, the fetus primarily relies on the mother for nutrition and oxygen. During this phase, changes in umbilical blood flow are mainly related to the mother's health status. If the pregnant woman feels discomfort or any abnormalities during this period, it is essential to seek medical attention promptly, follow the advice of professional doctors, and undergo necessary treatment.

2. Second Trimester - From the 14th week onward, the fetus has established its own blood circulation system and can obtain nutrition and oxygen through the placenta. At this time, changes in umbilical blood flow reflect more on the fetal growth and development. The normal range is 1.2-3.9. Values below this range may indicate fetal hypoxia in the uterus. Regular prenatal check-ups and following doctors' advice are key to ensuring the safety of both mother and fetus.

3. Third Trimester - Starting from the 30th week, the fetus is nearly fully formed, with a significant increase in weight. Changes in umbilical blood flow are mainly influenced by factors such as fetal weight gain and uterine enlargement. The normal range is 1.4-3.6. Values above the normal range may indicate the risk of complications such as gestational hypertension. Pregnant women should closely monitor their blood pressure and other related indicators and take measures as advised by their doctors.

The PI, RI, and S/D indicators of umbilical blood flow are essential components of health monitoring during pregnancy, helping to assess fetal development. Pregnant women should undergo regular prenatal check-ups and maintain communication with their doctors to ensure their own and their fetus's health. Understanding the normal ranges of these indicators can help pregnant women better comprehend their prenatal check-up results, promptly identify potential problems, and take appropriate measures. Future mothers must pay attention to their body's changes, maintain a healthy lifestyle, and prepare for the arrival of new life.