Single umbilical artery (SUA) is the most common abnormality found in the umbilical cord. Not all studies agree on the significance of this finding however. There are a few things that come from a review of the present knowledge:
- The incidence of SUA is between 0.5% and 7% of pregnancies.
- The following has been found to be more common in association with SUA: female fetal sex, maternal age over 40y, 3 previous children. Many will occur without these associations.
- About 10-15% of babies with SUA have a chromosome (gene) abnormality, however the vast majority of these are picked up by ultrasound antenatally.
- Ultrasound scanning is good at picking up other abnormalities if SUA is present, so a normal second trimester ultrasound otherwise is very reassuring.
- Even when the scan is reassuring, there is an association with both low birthweight ( less than 2.5kg) and early delivery (before 37 weeks).
In the presence of an otherwise normal scan, the only other change to antenatal care one might make is a growth scan to make sure the baby is growing normally in the third trimester.