Congenital Diseases

For every healthy set of parents, there is a basic 5 % risk of congenital malformation in their children. These vary in severity and have a wide range of possible causes. The main categories of problem are:

• Chromosomal abnormalities (e.g. trisomy 21) 
• Altered genetic traits - Single-gene defects (e.g., cystic fibrosis) 
• External influences (e.g., rubella embryopathy, alcohol embryopathy) 
• Multiple causes (e.g., cardiac abnormality, cleft lip, jaw or palate)
  

Chromosomal Abnormalities

Chromosomal abnormalities are irregularities visible under light microscopy in the number or structure of chromosomes, 23 pairs being the number normally present in humans. These abnormalities usually occur by chance during maturation of the egg or sperm cell; less often they are hereditary irregularities. Most de novo chromosomal abnormalities are so severe that they lead to miscarriage. The most frequently encountered chromosomal abnormality which the fetus survives is trisomy 21 (Down syndrome). Other chromosomal abnormalities occur less often, and the conditions they cause are sometimes more severe than trisomy 21 (e.g., trisomy 13, trisomy 18), and sometimes less severe (e.g., changes in sex chromosomes).

A handicap in the child due to the faulty arrangement of chromosomes can occur in pregnant women of any age. However, the probability increases with maternal age. The probability of giving birth to a child with trisomy 21 (Down syndrome) is 1:1600 for mothers aged 20 years, 1:900 for those aged 30 years, 1:350 for 35-year-olds, and 1:100 for mothers aged 40 years.

It is only possible to confirm the presence or absence of a chromosomal abnormality with absolute certainty by means of chromosomal analysis! This can be done, for instance, using cells taken from the amniotic fluid (amniocentesis) or from placental tissue (chorionic villus sampling).

The current recommendation is that pregnant women who are 35 years or over when they give birth should consider undergoing amniocentesis or chorionic villus sampling. Because of the inherent risk of these invasive procedures and due to the fact that about 50% of pregnancies with chromosomal abnormalities occur in women under 35 years, in many cases parents want an estimation of their individual risk, and this is possible using various techniques such as ultrasound and/or blood tests.

Advantages, limits and consequences of prenatal diagnosis

Using the procedures described above, many congenital anomalies can be diagnosed before birth. However, no prenatal examination can detect all possible diseases or malformations in the child. The predictive value of ultrasound examinations depends, for example, on stage of pregnancy, fetal position, placental position, amount of amniotic fluid, abdominal wall thickness, quality of the ultrasound equipment used, and the experience of the examiner.

In most cases, the results of prenatal diagnostic examinations are normal, which allays any justified or unjustified fears parents have, and allow the parents to experience the further course of pregnancy more calmly.

In some types of congenital anomalies such as serious heart defects and spinal or abdominal fissures, the results of treatment and prognosis can be significantly improved by optimized treatment during pregnancy, at birth, and in the immediate postnatal period thanks to prenatal diagnosis. Certain serious conditions in the child such as cardiac arrhythmias, cardiac insufficiency ("weak heart"), heart defects, blood diseases, infections, twin-to-twin transfusion syndrome (TTTS), spina bifida, or diaphragmatic hernia may also be treated successfully before birth.

Using ultrasound and Doppler sonography, it is also possible to detect growth retardation and a threat to the fetus posed by placental insufficiency (functional disturbance of the placenta). In such cases, harm to the child can be avoided by intensifying monitoring during pregnancy or by inducing birth before term.

If abnormal findings occur in one of the examinations carried out, we offer comprehensive consultation in our own practice and with specialists from the related field (e.g., neonatal medicine, pediatric surgery, pediatric cardiology, cardiac surgery, genetics), and, upon request, can put parents in touch with others similarly affected, self-help groups and other advice centers.

In special risk situations (e.g., inherited diseases or handicaps in the family), we recommend early genetic counseling.

We would be pleased to answer any questions you have in a personal consultation.

Your Team of Pränatalzentrum Stuttgart