Are single umbilical arteries normal?

Author

Emily Carr

Published Feb 22, 2026

Are single umbilical arteries normal?

The absence of one of the arteries is called single umbilical artery (SUA). It is one of the most common sonographic findings during pregnancy with an incidence range that goes from 0.5 to 6 percent in single pregnancies [1–3]. This incidence increases three or four times in twins pregnancies [4, 5].

Considering this, what happens if you have one umbilical artery?

Single umbilical artery is associated with an increased incidence of structural and chromosomal anomalies and growth restriction.

Subsequently, question is, how common are single umbilical artery? Single umbilical artery is when one artery in the umbilical cord is missing. It happens in about 1 in 100 singleton pregnancies (1 percent) and about 5 in 100 multiple pregnancies (5 percent). A singleton pregnancy is when you're pregnant with just one baby.

Herein, is single umbilical artery high risk?

Single umbilical artery risks.

Single artery umbilical cord problems only happen in around 1% of pregnancies, although the risk increases to 5% for twin pregnancies. A lack of one vessel is called a two-vessel cord. This condition increases the risk of: You having high blood pressure toward the end of your pregnancy.

Should I worry about single umbilical artery?

Your baby is likely to be fine. Having only one artery, called a single umbilical artery (SUA), shouldn't affect his health. Usually, an umbilical cord has two arteries, along with a single vein. The vein carries oxygen and nutrients to your baby, and the arteries remove waste products.

Is SUA high risk?

Birth Defects: Studies have found that there is a higher chance for other birth defects in a baby with SUA. This can include heart defects, kidney problems, spine defects, and other less common birth defects.

Does SUA mean Down syndrome?

In some cases, babies who have a single umbilical artery and a birth defect may be more likely to have a genetic condition (such as Down Syndrome). Important: Single umbilical artery by itself is not considered a birth defect. All babies with single umbilical artery are at risk for not growing as well in the uterus.

Can single umbilical artery affect baby?

There are many babies that have a single umbilical artery that have healthy pregnancies and deliveries. However, some babies with a single artery are at increased risk for birth defects. Examples of birth defects that babies with a two-vessel diagnosis may have include: heart problems.

Can single umbilical artery misdiagnosed?

Yes. Normal umbilical cords most commonly have three vessels (two arteries and one vein). A two-vessel cord does not imply fetal abnormality. In single gestations, approximately 50% of two-vessel cords (one artery and one vein) have no associated abnormalities.

How common is SUA?

The absence of one of the arteries is called single umbilical artery (SUA). It is one of the most common sonographic findings during pregnancy with an incidence range that goes from 0.5 to 6 percent in single pregnancies [1â€“3]. This incidence increases three or four times in twins pregnancies [4, 5].

Is single umbilical artery a soft marker?

One of these markers is actually represented by the single umbilical artery. This anomaly is made up of the presence of only two vessels (an artery and a vein) at the level of the umbilical cord, and its lack of an artery. The clinical meaning of this pathology is not yet completely known today.

Can SUA cause preterm labor?

SUA has been associated with various malformations and pathologies such as cardiac malformations, cleft lip or palate, esophageal atresia, ano-rectal atresia/stenosis (7) and adverse pregnancy outcomes such as preterm birth, diabetes, epilepsy, preeclampsia, polyhydramnios, and oligohydramnios (3).

When is single umbilical artery diagnosed?

In most cases, a single artery is found with an ultrasound. The test is done in the second trimester.

What does two vessel umbilical cord mean?

Most babies' umbilical cords have three blood vessels: one vein, which brings nutrients from the placenta to baby, and two arteries that bring waste back to the placenta. But a two-vessel cord has just one vein and one artery â€” that's why the condition is also referred to as having a single umbilical artery.

Why does the umbilical cord have 2 arteries?

The vein carries oxygen and nutrients from the placenta (which connects to the mother's blood supply) to the baby. The two arteries transport waste from the baby to the placenta (where waste is transferred to the mother's blood and disposed of by her kidneys).

What happens to umbilical artery after birth?

After birth, the proximal portions of the intraâ€abdominal umbilical arteries become the internal iliac and superior vesical arteries, while the distal portions are obliterated and form the medial umbilical ligaments. The umbilical veins arise from a convergence of venules that drain the extraâ€embryonic allantois.

What is an isolated single umbilical artery?

Background. Single umbilical artery (SUA) is characterized by the presence of one umbilical vein and the absence of one of the umbilical arteries instead of the normal umbilical cord containing one vein and two arteries (three-vessel cord), and is considered a malformation [1,2].

Are SUA babies born early?

[3] There is also an increased risk of intrauterine growth restriction, prematurity and mortality among neonates with SUA when compared with those with a three-vessel cord. [3,4] This baby was also born premature with a low birth weight.

Does SUA cause stillbirth?

GROWTH. SUA has been linked to an increased risk of growth restriction, stillbirth, and preterm birth. This association has primarily been reported in fetuses with other congenital anomalies.

Which vein is disappear in umbilical cord?

Persistent right umbilical vein

Very early in embryonic development, there are two umbilical veins as well as two arteries. Usually, the right umbilical vein disappears, and the left vein persists. In 0.2 to 0.5% of pregnancies, it is the left umbilical vein that disappears, leaving a persistent right umbilical vein.

Is a 3 vessel umbilical cord normal?

A normal umbilical cord has two arteries and one vein. This is known as a three-vessel cord. It is covered by a thick gelatinous substance known as Wharton's Jelly. The vein brings in oxygen and nutrients to the baby from the mother.

Does cutting the umbilical cord hurt?

Shortly after birth, it will be clamped and cut off. There are no nerve endings in your baby's cord, so it doesn't hurt when it is cut.

Can Down syndrome be seen at 20 week ultrasound?

A Detailed Anomaly Scan done at 20 weeks can only detect 50% of Down Syndrome cases. First Trimester Screening, using bloods and Nuchal Translucency measurement, done between 10-14 weeks, can detect 94% of cases and Non-invasive Prenatal Testing (NIPT) from 9 weeks can detect 99% of Down Syndrome cases.

How do you know if something is wrong with your umbilical cord?

An umbilical cord may become compressed or damaged before or during childbirth. Common signs of umbilical cord problems include an irregular fetal heartbeat and decreased or low fetal movement.

Can you see umbilical cord in ultrasound?

Signs The Umbilical Cord Is Around Baby's Neck

It's visible via ultrasound. Your practitioner can detect a nuchal cord about 70 percent of the time during routine ultrasounds, although it's usually not possible to determine if the cord is short or tight around the neck.

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Are single umbilical arteries normal?