Trisomy 13 and trisomy 18 (T13-18) are associated with high rates of perinatal death and with severe disability among survivors. Prenatal diagnosis (PND) may lead many women to terminate their pregnancy but some women choose to continue their pregnancy. We sent 503 invitations to answer a questionnaire to parents who belong to T13 and 18 internet support groups. Using mixed methods, we asked parents about their prenatal experience, their hopes, the life of their affected child, and their family experience. 332 parents answered questions about 272 children; 128 experienced PND. These parents, despite feeling pressure to terminate (61%) and being told that their baby would likely die before birth (94%), chose to continue the pregnancy. Their reasons included: moral beliefs (68%), child-centered reasons (64%), religious beliefs (48%), parent-centered reasons (28%), and practical reasons (6%). At the time of the diagnosis, most of these parents (80%) hoped to meet their child alive. By the time of birth, 25% chose a plan of full interventions. A choice of interventions at birth was associated with fewer major anomalies (P < 0.05). Parents describe "Special" healthcare providers as those who gave balanced and personalized information, respected their choice, and provided support. Parents make decisions to continue a pregnancy and choose a plan of care for their child according to their beliefs and their child's specific medical condition, respectively. Insights from parents' perspective can better enable healthcare providers to counsel and support families.