Genetic Counseling

During Pregnancy Planning

Couples who are planning pregnancies often seek the assistance of genetic counselors when one or both of the partners themselves, one or more of their existing children, or other family members are already affected by genetic conditions. Members of ethnic communities in which recessive genetic conditions are particularly prevalent also frequently seek genetic counseling during pregnancy planning. The genetic counselor gathers relevant information from the counselees to assess their risk of passing on a particular condition to the next generation. DNA testing (e.g., from a blood sample) is often required for a clear diagnosis.

During Pregnancy

In developed countries, it is now routine for pregnant women, especially those over 35 years old, to be offered some form of genetic testing. Noninvasive screening tests such as ultrasound or serum screening, conducted between 10 and 20 weeks of pregnancy, can provide information about whether the fetus is developing normally or is at increased risk (greater than 1 in 250) of being affected by a chromosomal condition (e.g., Down syndrome) or neural tube defect (e.g., spina bifida). Usually, these tests allow counselors to provide risk estimates, not conclusive results. Diagnostic tests such as amniocentesis or chorionic villus sampling (CVS) are performed after a positive screen result to obtain accurate results for chromosomal conditions such as Down syndrome. However, these tests also carry some risk of miscarriage (approximately 1 percent). Population pregnancy screening can identify only a limited number of common genetic conditions; most genetic conditions are rare and difficult to detect.

If a diagnostic test reveals a positive result (i.e., that the fetus is affected by a genetic condition), the woman must decide whether to terminate the pregnancy [Page 774]or continue with it and give birth to a disabled child. At this point, it is essential that the woman receives unbiased and accurate information about the relevant condition and feels supported in making the right decision for her.

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