My colleagues and I have created a survey for mothers of children with congenital heart disease. In our survey, we have a question asking each participant (mother) to indicate the number of pregnancies, including live births, abortions, and miscarriages.

Based on each participants responses, using branching logic, these mothers are asked additional questions for each pregnancy.

We want to capture "all" or at least "most" pregnancies in our US-based population. We are working with a cohort of 500+ women, now 40-50+ years of age.

From an OB standpoint, can you recommend a reasonable number to maximize capture of most/all pregnancies? Articles and supporting information also appreciated.