The big scan – something nearly every pregnant mother looks forward to.
Who has been growing in your belly for the last 18-20 weeks?
Many can’t wait to see a clear profile shot, and others are overjoyed to find out if they will be having a boy or a girl.
While breathtaking pictures and finding out the sex are what come to mind for the big scan, the purpose of the scan is to check out fetal development and growth. This scan is known as the anatomy scan.
Occasionally, a provider might find a fetal, umbilical or placental abnormality. One of the possible abnormalities is a single artery umbilical cord (SUA).
Anytime you hear “abnormality” in relation to your pregnancy, it can cause a great deal of worry.
But what is a single artery umbilical cord exactly? Does it mean you or your baby are at risk for complications?
What Is A Single Artery Umbilical Cord?
The umbilical cord is the lifeline between you and baby. During typical development, an umbilical cord has three vessels. One vein which brings your baby oxygen and nutrients, and two arteries which carry away waste from your baby to be processed via your kidneys.
A single artery umbilical cord has only two vessels. It has one vein, and instead of having two arteries it has just one. A single artery umbilical cord is also known as a two vessel cord.
Around 1% of singleton pregnancies have an SUA, and just under 5% of twin and multiple pregnancies have an SUA. It’s the most common umbilical abnormality.
Is A Single Artery Umbilical Cord Dangerous For My Baby?
Anytime you hear “abnormality” you’re likely to develop concern for the wellbeing of your baby. The good news, although an SUA is an abnormality, the majority of cases are isolated and not related to any dangerous conditions for you or baby.
Occasionally, a SUA can be related to other abnormalities in baby’s cardiovascular, renal or other systems, or related to a chromosomal issue. For this reason, your provider may recommend some further evaluations, but typically invasive testing isn’t recommended. A more detailed ultrasound to check for any other abnormalities and ongoing growth monitoring is a common course of action. If another abnormality is found, it might mean an increased risk of health concerns for your baby, but SUA alone isn’t the cause for concern.
Some studies have found a slight increased risk of Intrauterine Growth Restriction (IUGR), while others have concluded the risk of IUGR among babies with SUA is the same as the general population. If your provider is concerned about IUGR, they will recommend routine growth monitoring. Some cases of IUGR are attributed to placental function and blood flow, and the presence of a SUA might be a risk factor. However, as mentioned above, there aren’t studies which confirm an increased risk so it’s something to be aware of but not something to expect to occur.
Will SUA Affect Labour And Birth?
Many mother baby pairs experiencing SUA can still have a low risk, uncomplicated vaginal birth. Some studies, however, did find an increased risk of c-section due to small for gestational age (perhaps associated with IUGR) and fetal heartrate concerns showing signs of fetal distress.
One thing that is difficult to decipher with these increased risks is whether they’re due to the single artery umbilical cord or are they due to managing labour with SUA. If a baby is measuring small for gestational age or experiencing IUGR, a mother is more likely to be induced which increases the likelihood of fetal distress and c-section. With a single artery, it does seem that baby is at an increased risk of fetal distress and thus anything that also increases the risk of fetal distress (e.g. induction of labour, epidural, etc) could account for more c-sections or complications among babies with SUA due to combining risk factors.
As you and your maternity care provider monitor your pregnancy, and plan for your labor and birth, it’s a good idea to discuss how to manage these risks. If there isn’t a medical indication for an induction, augmentation or epidural, it’s likely planning an unmedicated vaginal birth with fetal monitoring could be ideal.
Anytime you hear something that deviates from expected normal, especially during pregnancy, concerns can run wild. While hearing your baby has a single artery umbilical cord can be scary, the good news is that more often than not your baby will be healthy and your labour unaffected. In the few situations where other conditions are present or where labour doesn’t unfold as planned, discussing your options with your maternity care provider before labour can help you be prepared.