Remember that song: "First comes love, then comes marriage, then comes the baby in the baby carriage"? In today's world, that isn't necessarily true anymore. Many people seek conception through artificial means like in vitro fertilization. Fertility clinics have waiting lists, thanks to couples who have trouble conceiving, women who wait to have children later in life, surrogates carrying children, same-sex couples, or others who might want to raise a child solo. What are the different reasons that people seek out fertility treatments? And how is that changing the nature of parenthood? Parents, aspiring parents, and a fertilization specialist share their stories.