With 20 to 25% of pregnant women affected, first trimester bleeding is relatively frequent (1). If bleeding in the first trimester is often associated, in the collective imagination, with the occurrence of a miscarriage, in reality they do not necessarily sign the termination of pregnancy. Thus, about half of pregnancies with bleeding in the first trimester progress normally (2).

This first trimester bleeding can have different causes.

During implantation, that is, when the fertilized egg implants in the uterine lining seven days after fertilization, small bleeding may occur. They are due to the rupture of small blood vessels in the uterine lining. These so-called implantation bleeds are not really rules-like: they are more pinkish or brown in color. They are sometimes accompanied by slight pain, such as cramps or tightness. These manifestations are benign and have no effect on the pregnancy.

Rarely, bleeding may occur on the due date of your period. We then speak of “birthday rules”, but if they are not actually rules since there is pregnancy and therefore no uterine lining to evacuate. This bleeding is also much less abundant than menstruation and does not last as long. They can be the consequence of a detachment of the trophoblast (placenta) which will then form a so-called deÌ ?? cidual hematoma, which will usually resolve spontaneously. Benign cervical lesions can also cause bleeding during pregnancy, especially after sex. Sometimes no cause is found.

Bleeding at the start of pregnancy should always lead to a consultation because it can be a sign of a complication of the pregnancy:

• spontaneous miscarriage
• an ectopic pregnancy
• a molar pregnancy

A clinical examination, an ultrasound and a blood test for the hormone beta-hCG will help to ensure the good progress of the pregnancy.

There is another case, certainly rarer, but it is still worth mentioning: denial of pregnancy, that is to say the fact that a pregnant woman is not aware of being pregnant. .

If the woman, unaware that she is pregnant, takes a contraceptive pill, it causes artificial periods or more exactly withdrawal bleeding due to the drop in hormone at the end of the platelet. This bleeding, less profuse but regular, can therefore be mistaken for a period. Genital bleeding, which is common in early pregnancy, can also be mistaken for a period.