Causes of abortion in the first trimester of pregnancy

Spontaneous abortion is the unintended interruption of pregnancy by the end of the twentieth week, i.e. before the fetus can hypothetically be able to survive outside the mother’s uterus independently.

Spontaneous abortions in the first trimester are quite frequent (about 20% of pregnancies end with an abortion) and often occur even before the woman has realized she is pregnant. The period most at risk ranges from the first weeks to the thirteenth (first trimester).


There are many causes of miscarriage and it is not always easy to really understand what went wrong. To eliminate, however, any sense of guilt, any regret, it must be said that there are not even real preventive behaviors (being at rest, not working ….). In a certain sense, it can be said, that if it has to happen, it happens.

Age: the age of the mother at the time of pregnancy is certainly a risk factor. The number of cases of abortion after the age of 35 increases considerably. And after the age of 40, one in three pregnancies is interrupted.

Genetic problems of the foetus: often spontaneous abortion in the first trimester occurs due to genetic malformations of the embryo that would make its extra-uterine life impossible (2 abortions out of 3 are due to this). In this case, in a certain sense, it is nature that defends itself and protects itself.

Multiple pregnancies: the uterus, subjected to too fast a growth, is unable to properly accept embryos that, in this way, cannot ‘attack’ and survive.

The woman’s uterine malformations: the woman’s uterine malformations (for example, a uterine cavity that is too small) make it impossible for the embryo to be properly implanted and thus unable to live. This fact affects about 1% of women.

Presence of polyps or fibroid: they are present in 20% of women and represent an obstacle for the continuation of pregnancy. If, therefore, you are looking for a child, first undergo a gynaecological examination and, if necessary, a surgical removal of the same (this is an outpatient operation that is resolved within a day of hospitalization).

Chronic diseases of the woman: hormonal disorders, thyroid problems, polycystic ovary syndrome… These are all risk factors for a good continuation of pregnancy.

Infections: some viruses and bacteria contracted during pregnancy, especially in the first trimester, may be responsible for the loss of the child (toxoplasmosis, listeriosis…).

Misbehaviour: smoking, alcohol, drugs can compromise the good progress of gestations, causing the premature death of the embryo.

Artificial fertilization: spontaneous abortions following artificial fertilization account for about 50-75% of the total. Pregnancy is interrupted after embryo transfer, causing bleeding that occurs around the expected date of menstruation. After assisted reproduction, the woman may therefore not even realize that conception has taken place.


Among the main symptoms are vaginal discharge and abdominal pain. It must be said, however, that blood loss in the first trimester is a fairly frequent phenomenon, especially if it occurs in conjunction with the days of menstruation. Therefore, the presence of blood is not always the cause of bad news: an immediate gynaecological examination will confirm or exclude abortion.

In the case of spontaneous abortion in the first few months, it is generally not necessary to have medical intervention and hospitalisation. This occurs independently and does not require any particular intervention.

Hospitalisation, on the other hand, may be necessary if the beat of the embryo is not perceptible, but the latter remains firmly implanted in the uterus. In this case, a scrape may be necessary.

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