The purpose of the initial pregnancy check-up with your gynaecologist is to exclude any possible health risks related to your pregnancy. This includes an ectopic pregnancy, for instance. The doctor will carry out a pap smear test, determine your blood type and work out whether you have antibodies against diseases like rubella and toxoplasmosis.
In the following monthly check-ups they will check your weight, blood pressure, the haemoglobin level in your blood, the size of your uterus (fundal height), the child’s heart rate and later on the position of the child. Urine samples are taken regularly and sometimes your gynaecologist will also check your cervix.
The doctor will carry out ultrasound examinations to check your baby’s developmental progress. Initially this involves measuring the crown-rump length. Later on in the pregnancy, progress is determined by measuring the diameter of the baby’s head. Between the 10th and 14th weeks of pregnancy, the doctor will also use ultrasound to measure the fold of skin on the baby’s neck. This helps to determine whether the baby has Down syndrome (trisomy 21).
The child’s sex can generally be determined from the 20th week of pregnancy onwards, as long as it is lying in the proper position and its genitals are visible.
These days, the best way to detect chromosomal disorders is with a first trimester test. The ideal time for this test is between the 11th and 14th weeks of pregnancy. It takes into consideration the woman’s age, her blood test results and the ultrasound measurements of the fold of skin on the baby’s neck.
If the test results are unusual, chorionic villus sampling will be carried out sometime between the 10th and 14th weeks of pregnancy. This involves removing and examining a sample of tissue from the placenta. The extracted cells contain the same chromosomes and genetic information as the baby. The procedure involved in chorionic villus sampling is not dangerous for the mother or the embryo; however, in incredibly rare cases it can lead to a miscarriage (the probability of this happening is only 1%).
The same examination can also be carried out later on in the pregnancy – then it is called a placental biopsy.
An amniotic fluid puncture (amniocentesis) is another method for determining chromosomal disorders. It involves extracting a sample of amniotic fluid sometime between the 14th and 18th weeks of pregnancy. The foetal cells present in the amniotic fluid are then examined over a two-week period. This procedure is also harmless and the risk of it causing a miscarriage is similarly just 1%.
Recently various non-invasive prenatal tests (NIPT) have also been officially approved (link only available in German). If the results of the first trimester test are unusual, a simple blood sample can be taken (maternal serum screening) in around the 11th week and these new prenatal tests can be used to make a reliable diagnosis about the most common chromosomal abnormalities.