Two years ago, before she had her baby girl Blue Ivy Carter, Beyonce suffered a miscarriage during the early stages of the pregnancy, US Weekly reports. "I picked out names," the pop star says in her new documentary Life Is But a Dream, premiering on HBO in February. "I envisioned what my child would look like... I was feeling very maternal." She says a doctor's visit revealed there was no heartbeat. "I went into the studio and wrote the saddest song I've ever written in my life," the singer says in the documentary. "And it was actually the first song I wrote for my album. It was the best form of therapy for me, because it was the saddest thing I've ever been through."