First trimester screening visits | The first trimester

First trimester screening visits

There are various examinations in the first trimester, which are mainly used to detect malformations in growing children. The prenatal test, a special blood test and nuchal translucency measurement are particularly well known. Screening in the first trimester of pregnancy is mainly used to monitor the child’s development.

In addition, if desired, various examinations for the detection of hereditary diseases (especially so-called chromosomal anomalies), for example Down’s syndrome, can be carried out with a prenatal test. Screening in the 1st trimester of pregnancy can be carried out between the 12th and 14th week of pregnancy. As a rule, screening in the 1st trimester of pregnancy can be used to check various blood values with regard to a possible chromosomal abnormality.

Especially the pregnancy-specific protein, the pregnancy-associated plasma protein A (short: PAPP-A) and the free beta subunit of HCG play a decisive role in this process. While PAPP-A is typically significantly reduced in Down syndrome, mothers of affected children show a significant increase in free beta-HCG. In addition to the specific blood tests, the so-called nuchal fold measurement (nuchal translucency measurement) can also be performed during screening in the 1st trimester of pregnancy.

The term “nuchal translucency” refers to a slightly darker area, corresponding to fluid, in the neck area of the child. In general it can be assumed that the nuchal fold is something completely normal and can be detected in most children in the 1st trimester of pregnancy. However, particularly high nuchal translucency goes hand in hand with an increased risk of the presence of a chromosomal abnormality, such as Down’s syndrome (trisomy 21).

Nevertheless, it should be taken into account in the screening of the 1st trimester of pregnancy that in most children with an enlarged nuchal fold there is still no chromosomal abnormality. For this reason, the measurement of the nuchal fold as screening in the 1st trimester of pregnancy is regarded as quite controversial. It can only be a first indication of a developmental disorder in the child and has a more unsettling than helpful effect on expectant mothers.


The human pregnancy is divided medically into three approximately equal sections. The division of pregnancy into a first, a second and a third trimester serves primarily to separate different stages of development of the unborn child. The first trimester of pregnancy begins even before the actual fertilisation of an egg, with the first day of the last menstrual period.

On the basis of this key date, the possible date of birth can already be calculated approximately at the beginning of the pregnancy. The expectant mother may experience severe symptoms, especially in the first trimester of pregnancy. The main reason for this is the rapid increase in the pregnancy hormone beta-hCG.

Typical symptoms of this part of the pregnancy include pronounced fatigue, nausea, frequent vomiting, headaches and mood swings. Contrary to common belief, early pregnancy is not only associated with severe nausea and vomiting in the morning hours. Affected women usually suffer from more or less pronounced symptoms throughout the day.

Most of the typical symptoms of the first part of pregnancy fortunately disappear completely by the end of the 1st trimester. Fetal development in the 1st trimester of pregnancy comprises a multitude of steps. During the first weeks before the actual start of pregnancy, the egg cell begins to mature.

Approximately between the 12th and 14th day of the menstrual cycle, ovulation occurs. From this moment on, the egg can be fertilised over a period of approximately 12 hours. After successful fertilisation, the first division cycles already begin in the fallopian tube.

A few days later, it can implant the fertilised egg in the uterus. Within the 1st trimester of pregnancy, almost all of the child’s organ systems are created. For this reason it is particularly important that the expectant mother has a balanced and healthy diet.

Particular attention should be paid to a sufficient supply of folic acid and vitamins during the 1st trimester of pregnancy. The 1st trimester of pregnancy ends with the beginning of the 13th week of pregnancy. At this time the risk of miscarriage decreases to a value of about 1-2 percent.