When is the highest risk period for single umbilical artery?

There is no specific statement about "which month carries the highest risk for single umbilical artery." However, the risks associated with single umbilical artery are relatively higher during mid-pregnancy (20–24 weeks) and late pregnancy (after 32 weeks). In mid-pregnancy, it is more likely to be accompanied by fetal structural abnormalities, while in late pregnancy, complications such as fetal growth restriction and hypoxia may occur. Enhanced prenatal monitoring is therefore necessary. If abnormal fetal development or abnormal fetal heart rate is detected during prenatal checkups, prompt medical attention is recommended.

The period of 20–24 weeks in mid-pregnancy is a critical window for fetal structural screening. Single umbilical artery may be associated with structural malformations such as cardiac or urinary system abnormalities. Abnormalities can be detected early through ultrasound examinations during this stage. Failure to timely identify these issues may delay opportunities for subsequent interventions and increase the risk of adverse outcomes at birth.

After 32 weeks in late pregnancy, fetal growth accelerates. Due to its reduced blood supply capacity compared to a two-vessel umbilical cord, a single umbilical artery may fail to meet the growing demands of the fetus, leading to growth restriction. It may also impair placental blood flow, resulting in intrauterine hypoxia; in severe cases, this could lead to poor pregnancy outcomes.

It is essential to strictly follow medical advice and attend regular prenatal checkups throughout pregnancy, with particular attention to ultrasound scans and fetal heart rate monitoring. Maintain a balanced diet rich in adequate protein and vitamins, avoid overexertion, ensure sufficient rest, and closely monitor changes in fetal movements to support healthy fetal development.