This leaflet is to help you understand what velamentous cord insertion is, what tests you need and the implication of being diagnosed for your baby.

What is a Velamentous cord insertion?

A velamentous cord insertion happens when the umbilical cord, which attaches the baby to the placenta, doesn’t insert directly into the placenta, but rather onto the membranes. This results in fetal blood vessels that are usually protected by the rubbery cord continue their course along the membranes before inserting into the placenta. 

How does a velamentous cord insertion happen?

It is not clear why a velamentous cord insertion occurs. There is speculation that while the cord may have inserted correctly at the beginning of the pregnancy, changes in the placental shape and relative position during gestation, may result in the cord not following precisely.

Should I have more tests done?

Doctors will check for structural differences (anomalies) in the baby when a velamentous cord insertion is seen. Usually, no other anomalies are present. 

Because velamentous cord insertion can sometimes be associated with smaller babies, your doctor will likely prescribe serial ultrasounds to monitor the growth of the baby, usually every 4-6 weeks and starting at approximately 24 weeks of pregnancy. 

If the vessels are close to your cervix, the doctor may do a vaginal ultrasound to check to see whether the placenta is low-lying and whether the unprotected vessels travel over the cervix, a condition known as vasa previa. This is an important distinction to make as vessels overlying the cervix are at risk for rupture during or before labour.

What are the things to watch for during the pregnancy?

Most pregnancies will remain uncomplicated. However, any loss of fluid or contractions should prompt you to go see your doctor as this may cause some compression of the vessels. 

What does it mean for my baby after it is born?

An isolated velamentous cord insertion, not associated with vasa previa should not have any effects on your baby after it is born. 

Will it happen again?

The risk of velamentous cord insertion happening again is the same as for any pregnancy, which is about 1%. The risk is slightly higher in twins. 


Last updated April 2023