Dear Doctor: My second husband and I have tried to get pregnant for over a year now, but we have had no luck. Should we be worried about infertility? I’m the mother of a 2-year-old girl and a 4-year-old boy, so the problem probably isn’t with me. What causes that in a man? Dear Reader: When a woman and man have not achieved pregnancy after a year of regular unprotected sex, they meet the clinical …