Many genetic diseases can be diagnosed during pregnancy, including Down’s syndrome, Thalassemia Major, Sickle Cell Disease, and more. Two techniques are available: Chorionic Villi Sampling performed between 10 and 12 weeks of pregnancy, and Amniocentesis performed between 15 and 18 weeks. Both carry small risks of miscarriages and other adverse effects.
Before opting for either of these, pregnant women (with or without their partners) should receive an extensive session of genetic counseling. It’s important to understand what condition is being sought, what the chances of it are, what are its range of possible manifestations, and what are the risks of the procedure. The ultimate reason behind Prenatal Diagnosis is to decide to terminate a pregnancy (so a woman completely opposed to abortion would not be interested). Some genetic diseases are 100% fatal in early life, so decision-making would be easy. But others can range from mild to severe, so prospective parents need to be able to understand all possibilities.