John Legend has encouraged couples having trouble conceiving naturally to try IVF fertility treatment.

The 38-year-old singer and his wife Chrissy Teigen conceived their nine-month-old daughter Luna through in-vitro fertilization, which is where eggs are collected and fertilized by sperm in a lab, then implanted back into the woman's uterus.

The All of Me hitmaker has urged other couples who are having fertility issues to try IVF, after it worked so well for him and Chrissy. "There are some who look down on people that have fertility issues and need to use IVF. We have had fertility issues for years and had to use IVF," he told Newsweek Europe.

"Some people can't reproduce naturally. We're glad we had Luna the way we did, and hopefully we'll have a few more kids through IVF," John added. "We think it's a viable issue for people having fertility issues and encourage people that can't have kids the old-fashioned way to do it the way we've done it."

Sports Illustrated model Chrissy has been open with her fertility issues, sharing last year (16) she had chosen a female embryo so John could have a daughter. The 31-year-old came under fire for her comments, with some criticizing the model for picking the gender of her unborn child.

However, John said in his interview to Newsweek Europe he believes it's important for a woman to be in control of when, how and if she wants a child.

"Having control over reproduction is one of the most important rights a woman has. Choosing when you want to have a child or not affects so much of your life and your body," he said.

Chrissy recently revealed on Twitter her and John are planning on having another child in the future, also through IVF treatment. "Since this is coming up again, I said our next baby would be a boy because that is the embryo we have left. A boy. So. Yeah," she wrote in January (17). "And no, I am not pregnant."