About 13 out of every 100 couples cannot get pregnant. It's a stressful and emotional time, and it's often considered a female issue. The CDC says both men and women contribute to infertility in about 35 percent of couples. The man is the only factor in about eight percent of cases. Dr. Tara Narula joins "CBS This Morning" to discuss some of the causes of male infertility and why it's so difficult for men to talk about the issue.