Kimberley Soranno, a 39-year-old Brooklynite undergoing an in vitro fertilization cycle as part of her quest to become pregnant, had gone to her share of yoga classes, but never one like that held on a recent Tuesday night in a reception area of the New York University Fertility Center. There were no deep twists or headstands; just easy “restorative” poses as the teacher, Tracy Toon Spencer, guided the participants — most of them women struggling to conceive — to let go of their worries.

“Verbally, she brings you to a relaxation place in your mind,” Mrs. Soranno said, adding, “It’s great to do the poses, get energy out and feel …