Pregnancy and Rh-conflict – table of Rh factors, possible complications

Rh sensitization during pregnancyWhen registering with an antenatal clinic, the expectant mother is always assigned a number of tests, including a blood test to determine the Rh factor. Dad will have to pass a similar analysis. Moreover, the result of my father’s analysis is the most important …

The content of the article:

  1. Causes of Rh sensitization and gestational age
  2. The mechanism of development of the Rh-conflict
  3. Rh-conflict symptoms and complications

Causes of Rh sensitization during pregnancy – how long does it occur?

The term “rhesus” is usually called a complex consisting of 50 specific antigens that are located on erythrocytes.

The most important among all groups of antigens are group D proteins, which are taken into account by specialists at the time of determining the rhesus of the expectant mother.

Most of the world’s inhabitants have a positive Rh factor, confirmed by the content of D-antigen in their blood (approx. – Rh +). The remaining 15% of this antigen is absent in the blood, and their blood is Rh-negative (approx. – Rh-).

In ordinary life, Rh-negative blood is not a sentence – and, in general, does not affect life at all.

But during pregnancy or in the case of a blood transfusion, such a feature can cause a lot of problems.

Rh-conflict between mother and fetus during pregnancy

On a note:

When using the terms “positive” or “negative” Rh factor, it is meant exclusively the presence or absence of the D-antigen (despite the presence of other groups of proteins).

Rh factor in different nations

  • Statistics show that 85% of Europeans have Rh-positive blood.
  • But among residents of Asia and India, this percentage is much higher – it reaches 99%.
  • In the Basques, a third of the population will have negative rhesus.
  • And black inhabitants of the earth have Rh negative blood only in 7% of cases.

Video: Pregnancy and Rh-conflict: risks for mom and baby

What is Rh Sensitization?

This diagnosis is usually made by a specialist after detecting Rh antibodies in maternal blood.

From the name it is clear that Rh antibodies arise as a “protest” against foreign erythrocytes. Compounds of the protein structure in mother’s blood, with its negative Rh factor, are formed when “foreign” Rh-positive children’s erythrocytes enter the body.

That is, the mother’s immune system refuses to accept other people’s erythrocytes as their own, as a result of which a Rh conflict, called sensitization, arises.

The development of a Rh-conflict is impossible if a baby with a negative Rh lives with a Rh-negative mother. The conflict arises exclusively when the mother’s body becomes more sensitive to a specific agent.

Not dangerous for the mother herself, sensitization can cause a miscarriage or (which often happens) the development of hemolytic disease of the baby.


  1. It does not matter the baby’s Rh factor if the mother’s blood is Rh positive.
  2. You don’t have to be afraid of sensitization if mom and baby have negative rhesus.

What are the causes of Rh-conflict?

Key reasons include …

Simply put, any situation in which the blood of the fetus and the mother mixes can cause the formation of a Rh-conflict.

That is why experts categorically do not recommend that young mothers with Rh-negative blood terminate their first pregnancy, which, in most cases, mothers endure without problems (it is the second pregnancy that accounts for a high percentage of Rh-conflicts).

But after an abortion, the Rh-negative mother of the 2nd pregnancy may simply not happen.

How long can a Rh-conflict occur?

Usually, this pathology begins to manifest itself already from the 6-8th week of fetal development – when D-protein appears on the erythrocytes of the crumbs.

That is why the determination of the content of antibodies in maternal blood is carried out regularly (monthly), from the moment of registration.

On a note:

Changing the Rh factor during pregnancy is impossible due to the fact that this protein is genetically inherited and remains unchanged until the end of life.

Pregnancy and Rh-conflict

The mechanism of development of the Rh-conflict during pregnancy – a table of the probability of the Rh factors of the parents and the child

The Rh factor is passed on to the fetus along with the genes of the dad. It is the father who is responsible for what the baby’s Rh will be.

In every man, D-protein control is carried out by genes that are located on a pair of chromosomes.

  1. With dominant genes (in 45% of cases), a man has Rh-positive blood. Such a man will always have Rh-positive children.
  2. In the case when a dominant gene is present on one chromosome of the dad, and the other is recessive (in 55% of cases), only in 50% of cases a Rh-positive baby will be born.

Given that it is extremely difficult to determine genes in advance, these studies are carried out only in case of urgent need (for example, during the IVF procedure).

It is impossible to predict a baby’s Rh. The possibility of rhesus negative crumbs appearing ranges from 25 to 75 percent in the case of different parental rhesus.

But it is important to remember that for the 1st pregnancy, Rh-conflict is possible only in 5% of all cases. During this first pregnancy, there is no mixing of the blood of the mother and the baby, therefore the Rh-conflict is a rare occurrence.

The risk increases only when the baby’s Rh-negative blood gets into the mother’s Rh-positive erythrocytes …

  • With increased permeability of placental vessels.
  • With gestosis, with the threat of miscarriage, or with diseases that can disrupt the integrity of the vessels of the placenta.
  • For diagnostic procedures that can lead to mixing of the blood of the mother and the fetus.
  • During childbirth and caesarean section.
  • In the case of manual separation of the placenta or with its early detachment.
  • With surgery (approx. – ectopic, miscarriage, abortion).

After the first penetration of foreign proteins into mother’s blood, IgM antibodies are synthesized. But the molecule is large, and is unable to enter the fetal bloodstream – as a result, the most severe complication (in most cases) is premature birth.

What happens in the second pregnancy?

By the second pregnancy, the mother’s Rh-negative organism is already familiar with the positive Rh factor, and repeated contact with it becomes the reason for the rapid production of a serious amount of much smaller IgG antibodies, which already freely penetrate the baby through the placental vessels, causing the above consequences.

In fairness (and the peace of mind of expectant mothers), it is worth noting that the Rh-conflict can be avoided – even if the mother’s Rhesus and the crumbs do not coincide, with the competent supervision of the expectant mother by professional specialists.

What is the likelihood of Rh-conflict between mother and fetus – table

Mom (Rh +) + Dad (Rh +)

Baby’s Rhesus 75% Rh + / 25% Rh

There is no likelihood of conflict

Mum (Rh-) + dad (Rh+)

Baby’s Rhesus 50% Rh + / 50% Rh

The likelihood of conflict is 50%

Mom (Rh +) + Dad (Rh-)

Baby’s Rhesus 50% Rh + / 50% Rh

There is no likelihood of conflict

Mom (Rh-) + Dad (Rh-)

Baby’s Rhesus 100% Rh

There is no likelihood of conflict

Symptoms of Rh-conflict during pregnancy – possible complications for the mother and fetus

There are no specific signs by which one could determine – or at least suspect – that the expectant mother has a Rh-conflict simply does not exist. In addition, this phenomenon has absolutely no effect on her health.

In a word, the identification of the problem is possible only during the examination.

  • A blood test for antibodies. If the titer rate is exceeded, doctors talk about the development of Rh-conflict.
  • Ultrasound. This procedure for Rh-conflict will show an increase in the size of the internal organs of the fetus, as a result of hemolysis of erythrocytes. Also, doctors look at the presence of edema of the fetus, its position, the thickness of the placenta.
  • Doppler ultrasonography… It will help assess the quality of blood flow in the blood vessels of the placenta.
  • Cardiography. It is carried out to analyze the heart rate of the crumbs.

In the presence of several symptoms at once, a more thorough examination of the fetus is prescribed to exclude or diagnose hemolytic disease in him.

What is the danger of Rh-conflict?

As mentioned above, the main danger in the incompatibility of the rhesus of the mother and the baby is considered to be hemolytic disease, which can threaten both the fetus and the newborn.

When the mother’s antibodies attack the erythrocytes of the fetus, the latter are quickly destroyed, as a result of which anemia begins, organ enlargement, thickening of the placenta, hypoxia, etc.

The severity of the consequences of the Rh-conflict for the baby will depend on the period of isoimmunization, on the viability of the fetus itself and on the activity of the production of the necessary anti-Rh immunoglobulins in mother’s blood.

Pregnancy. What if a woman has a negative Rh factor?

This article is by no means a substitute for the doctor-patient relationship. It is informative in nature and is not a guide for self-medication and diagnosis.

The website reminds you that in all doubtful situations with health, you should never delay or ignore a visit to a doctor!

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