In everyday language, we speak of rhesus incompatibility at birth and, in medical terms, of fetomaternal anti-rhesus D alloimmunization in rhesus D negative pregnant women. This event – which occurs when a rhesus D negative mother carries a baby with a rhesus D positive blood group – requires special monitoring and preventive measures to avoid complications for the fetus or the baby during pregnancy or during pregnancy. of childbirth. The explanations of Dr. Franck Mauviel, head of the obstetrics gynecology department at Sainte-Musse hospital in Toulon.
What is Rh incompatibility during pregnancy or at birth?
Feto-maternal anti-rhesus D alloimmunization concerns women with a negative rhesus D blood group (RH:-1), when the parent is rhesus D positive (RH1). The passage through the mother’s body of rhesus-positive red blood cells from the fetus leads to immunization: the maternal body produces antibodies (anti-D IgG Ac) once morest rhesus D, a protein present on the surface of the red blood cells that he does not recognize as his own. This immune response can occur in the event of bleeding during pregnancy, during amniocentesis, at the time of birth but also during a transfusion or fortuitously.
Is this immunization phenomenon systematic in this configuration?
In 25% of cases, the fetus of a rhesus negative mother with a rhesus positive sire is rhesus negative. In this case, there is no problem. But in 75% of cases, the fetus is also rhesus positive. In a normal situation, this does not pose a major problem: the blood circulation of the fetus is isolated from the maternal circulation by the barrier of the placenta. If the mother becomes immunized during pregnancy (following bleeding, shock on the stomach, etc.), she will produce antibodies once morest rhesus, but this phenomenon of immunization takes some time: the pregnancy is terminated before be a serious risk to the baby. This is more at risk for subsequent pregnancies, because the anti-D IgG antibodies, already present in the maternal circulation from the start of pregnancy, cross the placenta, arrive in the blood circulation of the fetus and destroy its red blood cells, carriers of rhesus d.
What are the risks for the baby?
The destruction of red blood cells leads to a risk of more or less severe fetal or neonatal anemia, requiring blood transfusions, before or following childbirth depending on the case. The rapid destruction of red blood cells also leads to an overproduction of bilirubin causing jaundice: without treatment, very high levels of bilirubin in the blood can cause brain damage, we speak of kernicterus. There is also a risk of heart failure and even death. But this should no longer exist if we take into account the recommendations in terms of screening and prevention.
How is screening done?
The analysis of the circulating fetal DNA found in the maternal blood makes it possible to determine the rhesus of the fetus. It must be carried out in any rhesus negative woman when the parent is RH1 or unknown, thanks to a simple blood test, during the first trimester of pregnancy.
What preventive measures when rhesus incompatibility is proven?
Primary prevention concerns all RH:-1 women with an RH1 baby. This is the injection at the beginning of the 3rd trimester of a drug derived from blood, Rhophylac, which destroys the antibodies that attack the rhesus. It is systematic because there are many hidden, undetected immunizations. Targeted prevention is put in place if a risky situation arises: bleeding, an abortion, or during childbirth.
Is it a contraindication for breastfeeding?
Absolutely not. Are there other similar forms of immunizations, linked to blood type? Other proteins on red blood cells can also cause immunizations. For example, a woman with type O can produce anti A or anti B antibodies. birth, with a cord blood sample.
Pauline and her companion with their sons today in great shape!(Photo C. R.).
More info
The Mediterranean perinatal network chaired by Professor Florence Bretelle administers a website (1) which makes available to the general public the protocols applicable in the monitoring of normal pregnancies or pregnancies at particular risk, in particular that concerning “the prevention of allo – fetomaternal anti-rhesus D immunization in pregnant women”, written by Dr Mauviel and Dr Floriane Schneider, from the Cannes hospital center.
1. www.reseauperinatmed.fr
Pauline: “Both times, my babies had to be transfused”
In Garéoult (Var), Pauline Sosé is the mother of two boys, Ezio (2 years old) and Thao (5 months). During each of her pregnancies, she had to deal with the problem of rhesus incompatibility between her group blood and that of her babies.
« For the first, I did not have a blood test at the beginning of the pregnancy. I had some bleeding following a move, that’s when the doctors saw for rh incompatibility. Ezio had a transfusion at birth. For the second, it was much more complicated, says the young mother. The antibody levels rose very high, because they attack harder with each pregnancy. The teams were amazed that the baby held up. We went through a lot of things, a lot of stress. Every week, we checked his heart rate, the amount of amniotic fluid, that he was not lacking in oxygen – this is the risk in the event of anemia, there is a lack of red blood cells to transport oxygen. Finally, he was not too anemic, we avoided the in utero transfusion and a too premature birth. »
Thao was born at 35 weeks.«I saw him for 20 minutes then he left for phototherapy to treat the jaundice. Twice he had to be transfused because the anemia had reached the transfusion threshold. At two months, he began to re-manufacture his red blood cells on his own and it was not until he was three months old that we were sure he was out of the woods. »
Today, if she testifies, it is also to remind us of the importance of blood donation.“Without donors, there’s no transfusion. It’s also to them that my sons owe their lives. We want to thank them! »
To donate blood, simply go to the EFS website to find the nearest collection points: https://dondesang.efs.sante.fr
