Let’s start with the basics of the umbilical cord. The umbilical cord is the connection between your baby and the placenta. 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. The arteries are used to transport waste away from the baby to the mother via her kidneys.
The umbilical cord starts to form early in pregnancy, around the fifth week of gestation. It will get longer and take the famous coil shape as it does. The average length of an umbilical cord is about twenty-two to twenty-four inches.
If you are having a mid-pregnancy ultrasound, also known as a fetal anatomy survey, your ultrasonagrapher will examine the placenta. They are looking for many things. They will try to see both the arteries and vein during your exam. This is easier done with color Doppler ultrasounds, but can be done with your average ultrasound machine. They may or may not say anything with the exam. The size and location of the placenta and umbilical cord will be noted.
The Wharton’s Jelly is very thick and helps protect the arteries and vein from being compressed during your pregnancy as your baby grows and the cord gets pressed and even potentially knotted in about one percent of all births. This is more common in identical twin pregnancies or if your baby’s umbilical cord is longer than normal.
Most knots remain loose and do not pose a threat to your baby, but it is believed to be the cause about five percent of stillbirths. Fetal monitoring is one method used to look for cord anomalies, and when certain heart rate changes occur, a cesarean birth may be the best option for your baby.