By allowing vital exchanges between the mother and the child in utero, the umbilical cord is one of the guarantors of the good progress of the pregnancy. But how does it evolve during gestation and at the time of birth? Can it be a source of complications during these special 9 months? Some answers.

The umbilical cord is formed, under the effect of the increase in amniotic fluid, between the 4th and the 8th week of pregnancy following the fusion of the chorion and the amnion, the two membranes which form the amniotic cavity. An essential organ for the continuation of pregnancy, the umbilical cord connects the child, by being inserted on the umbilicus, to the mother, by inserting itself on the fetal face of the placenta. It ensures, via the placenta, all the vital exchanges necessary for the proper development of the embryo, then the fetus.

Its appearance is variable during pregnancy:

• until the 3rd of pregnancy, the cord is short but thick. At this stage, it contains the intestinal loops of the embryo due to lack of space in its abdominal cavity. These will later form part of his digestive system.
• Subsequently, the cord lengthens, in particular to allow the fetus to move without constraint in the amniotic fluid. It measures on average, at the end of gestation, between 50 and 60 cm, but can sometimes be shorter (30 cm) or longer (up to 1 m). The umbilical cord can also be more or less thick, but measures on average, 1,5 cm in diameter.

From an anatomical point of view, the umbilical cord is made up of connective tissue and blood vessels, produced by the amnion. More precisely, it consists of:

• an amniotic coating, made up of a single layer of amniotic cells,
• Wharton’s jelly, a connective tissue, which surrounds it, giving it its tone and protecting it from possible pressures,
• two umbilical arteries, which lead the blood from the fetus to the placenta,
• of a vein, bigger, which draws placental blood from the mother’s body and directs it to the organs of the unborn baby.

The umbilical cord plays a decisive role: it ensures the circulation between the fetus and the placenta and thus allows:

• to nourish and oxygenate the unborn child thanks to the umbilical vein,
• to evacuate waste due to fetal metabolism (urea, CO2) through the umbilical arteries. The placenta then acts as a filter before discharging the said waste into the maternal circulation which in turn discharges it.

Different types of umbilical cord malformations and abnormalities can occur during pregnancy. Among them are:

Morphological abnormalities 

 These are related to the shape of the cord. We thus identify:

• the short cord: less than 30 cm, it is usually due to a lack of uterine space (especially oligoamnios) or reduced fetal movement. Rare (1% of pregnancies), this malformation can especially have consequences during childbirth (prolongation of the duration of labor, abnormalities in the progression of the presentation of the baby, disorder of the heart rhythm of the fetus, etc.). anomalies of plication of the embryo in the early stages of development (defective closure of the abdominal and thoracic wall). We speak of Cantrell’s pentalogy linked to a short cordon sequence.
• the long cord, over 70 cm or 1 m, is also rare (6 to 7% and 1% of pregnancies respectively). It can be at the origin of knots or circulars (winding of the cord around a part of the body of the fetus). Very rarely serious during pregnancy (unless they are associated with a hydramnios), they can however sometimes promote certain complications during childbirth (lengthening of labor, placental abruption and in more serious cases, cord prolapse).
• the lean cord, whose diameter is less than 1 cm is often a sign of intrauterine growth retardation.
• le cordon gras, whose diameter exceeds 2 cm, is often accompanied by edema, which if isolated, presents no risk to the baby.

Insertion anomalies

Very rarely, the umbilical cord may be improperly inserted into the placenta. We then speak of insertion anomalies. The main anomaly that can lead to complications: velamentous insertion. In about 1% of pregnancies, the cord is thus inserted directly into the membranes, about 2 cm from the edge of the placenta. This abnormality is sometimes accompanied by fetal malformations, a single umbilical artery (AOU), or intrauterine growth retardation (IUGR). It is more common when the placenta is inserted low. Main consequence of velamentous insertion: the cord is not protected by Wharton’s jelly. Results :

• regular cord compressions may occur, sometimes causing growth retardation,
• compression, stretching or even rupture of the umbilical vessels can occur during labor, fortunately very rarely causing bleeding.

Abnormalities of the vessels of the cord

 These abnormalities can be of several forms (a supernumerary vein or umbilical artery, for example). However, the main anomaly of the umbilical vessels remains single umbilical artery (AOU). Extremely rare (between 0,2 and 1,1% of pregnancies), this anomaly is favored by maternal diabetes or twin pregnancies. It can sometimes be associated with fetal malformations and chromosomal abnormalities (trisomy 18), of the skeleton or of the urinary, digestive or circulatory systems, or even with intrauterine growth retardation. Even if it does not endanger the vital prognosis of the unborn child, AOU should be closely monitored because of the high risk of malformations. The follow-up is then organized in two stages:

• during pregnancy, a morphological study of the future baby by ultrasound is carried out,
• after birth, a thorough examination of the newborn is carried out to detect any abnormalities and a renal and urinary ultrasound may be recommended in the baby’s 9th month.

At birth, the umbilical cord loses its usefulness. Indeed, the first inspiration of the infant allows him to oxygenate himself naturally while his food and his nutritional contributions are provided by the mother, via breastfeeding or infant milk. Before delivery (expulsion of the placenta) which puts an end to exchanges between the uterus and the placenta, the umbilical cord must therefore be cut. If, in France, early clamping of the umbilical cord (10 to 20 seconds after birth) is usual, several studies have questioned obstetric practices by recommending late clamping, within 2 to 3 minutes after birth. In question: the late clamping (carried out under certain conditions), would allow, by promoting an additional blood supply to the infant, to increase its ferritin level and thus to avoid the iron deficiencies usually observed around the 4 months of the child. .

This practice has since been the subject of an opinion from the French National College of Obstetrician Gynecologists (CNGOF) which has declared itself in favor of late clamping in the event of prematurity of the child only. The explanation: this gesture would increase the hematocrit level in premature babies, thus reducing the need for transfusion due to anemia. Conversely, for the child born at term, the CNGOF confirms the practice of early clamping, the delayed section of the cord increasing in these infants the risk of jaundice requiring phototherapy.

At the time of birth, the umbilical cord is severed approximately 1,5 cm from the newborn’s umbilicus. Depending on the maternity ward and the protocols in place, the cord is then left in the open or surrounded by a bandage. It must then be the subject of daily care until healing and its fall, generally 5 to 10 days after birth. It then consists of:

• wash your hands beforehand before performing the treatment,
• clean the base of the cord using a sterile compress and a Bispetine-type disinfectant, going from the skin to the end of the cord.
• sometimes carry out (on the advice of the practitioner) a dressing using two compresses, one around the base of the cord, the other on top, before maintaining the whole with a net.
• fold back the diaper after cleaning to avoid urine contamination.

The care can be stopped at the healing, which is generally noticeable by the absence of oozing on the compress.