Does the presence of the umbilical cord around the baby’s neck in an obstetric ultrasound significantly affect the health of the baby?
Pregnancy is often an exciting milestone for many women and their families. However there are moments that could create a lot of anxiety and uncertainty during the course of the pregnancy. Accordingly pregnant women are encouraged to attend prenatal clinics. During these clinics a number of investigations are done.
The aim of the investigations is to determine whether the mother and the baby are healthy, and identify any conditions that may benefit from prenatal interventions. The results from these tests should therefore be correctly interpreted and communicated to the patient. Misinterpretation of results may lead to inappropriate interventions.
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One such very useful prenatal test is the obstetric ultrasound. While some women regard it as an opportunity to determine the sex of the baby, an ultrasound provides a lot more information about the wellbeing of the baby.
Just like an adult not all babies are the same. Some may exhibit uncommon features that are otherwise normal. It is the duty of the doctor to differentiate features that may significantly affect the health of the baby from those that will not.
Some features are constant such as extra fingers in an otherwise normal baby. Others are variable. This means if you see them today it doesn’t necessarily mean they will be present next time the scan is carried out.
One such feature is the umbilical cord being around the baby’s neck. Unfortunately this is commonly sought after at the expense of more important features such as blood flow to and from the placenta. It is important to note that more than half of babies in the womb will have a cord round the neck at some point in the pregnancy but only 25 to 40 per cent are born with it. It all depends on the location of the baby as it moves in and out of the different loops of the umbilical cord. So how does the baby survive in the womb and does the findings of the scan impact on the health of the baby? Babies in the womb get their nutrients and oxygen from the mother through the placenta (also known as the after birth) via the umbilical cord. The umbilical cord is on average 55 cm long, rope-like stricture that consists of three blood vessels along its length. The vessels are well protected with a slimy membrane and a jelly like substance (Wharton’s Jelly).
The vessels in the cord include one umbilical vein which pumps blood from the placenta to the baby and two umbilical arteries that drain blood from the baby back to the placenta. In simple terms the vein contains nutrient and oxygen-rich blood while the two arteries contain used blood with waste products. The placenta acts as the main exchange organ between the mother and the baby. Babies therefore do not breath while in the womb and there is no oxygen travelling down their throat to the lungs. The first useful breath the baby takes is at birth. For this reason, it is not physiologically possible to strangulate, or choke the baby to death while in the womb.
Let us assume for a moment that science is wrong and babies do indeed breath in the womb through the windpipe. If this were the case then one would require a lot of force on both ends of the cord to strangulate the baby. Remember the cord is a jelly-like, slimy structure and the force required would have to be more that that of an ordinary rope. Some may, however, argue that they gave birth to a dead baby that had been strangulated by the cord as the cord was round the neck. The truth is that this could just be a coincidence. As previously mentioned 25 to 40 per cent of women will give birth normally with the cord around the neck without having experienced a problem during pregnancy, or labour.
It is therefore not true that a cord round the neck can kill a baby, but it is very important that thorough investigations and autopsy are conducted to ascertain the cause of death and not to assume it was caused by the presence of cord around the neck.
Performing a scan at the late stages of pregnancy to ascertain whether the cord is around the neck is unnecessary and does not improve the outcomes of pregnancy. There are more useful parameters such as the growth of the baby and the flow of blood through the brain and the umbilical cord that would inform us about the wellbeing of the baby.
Looking for the presence of umbilical cord around the neck only creates a lot of anxiety to the mother and leads to inappropriate interventions in an otherwise healthy pregnancy.