Singer-songwriter John Legend and model wife Chrissy Teigen say struggling to conceive and ultimately undergoing in-vitro fertilisation have brought them closer.

“Having a baby is a big challenge for a couple, and going through that together strengthens your bond because if you can make it through [having a child], you know you can make it through anything,” Legend told Cosmopolitan.

The interview follows the birth of their 16-month-old daughter, Luna Stephens, in April last year, who was conceived with IVF.

The couple has now revealed they will use IVF again in the hopes of giving Luna a little brother or sister.

“We’re lucky that we’re living in an age where we can conceive in other ways; [IVF] brought us Luna and hopefully, it will bring us a few more awesome kids too,” Legend said.

The 10-time Grammy winner confirmed they had been challenged enough  in their efforts to have a baby that turned to medical science for help.

“I think it’s especially difficult when you can’t conceive naturally,” Legend said.

“You want to feel like everything’s working properly and want everything to be perfect, but sometimes it’s not,” the singer-songwriter and father-of-one said.

The All of Me singer and his cookbook-author spouse were seen on Wednesday (US time) taking time off on a super yacht in Sardinia, Italy

IVF Australia clinical director and University of New South Wales Associate Professor Gavin Sacks told The New Daily it was quite common for IVF to clinch and strengthen relationships.

Professor Sacks said he had assisted many infertile couples, adding that it was relatively rare to see a break-up through the course of an investigational treatment.

“The journey becomes a big part of what the couple share together,” Prof Sacks said.

Legend also shared the couple’s IVF journey on a British morning television program, saying people shouldn’t be afraid to talk openly about the topic.

“A lot of people struggle with fertility and they shouldn’t be ashamed of it,” he said.

“A lot of people want to have kids and maybe can’t do it the natural way … I think people should do it if that’s what will work for them.”

Teigen shared with People the celebrity couple’s decision to have a girl in February last year.

“Not only am I having a girl, but I picked the girl from her little embryo. I picker her and was like, ‘Let’s put in a girl’,” she told the magazine.

At the time she said a boy would follow. “We’ll get there too, so it’s not like we really have to pick”.

Mum Chrissy Teigen and father John Legend help little Luna Stephens throw the ceremonial first pitch at a July Seattle Mariners-Minnesota Twins in Seattle. Photo: Getty

The unwavering couple of 10 years have also been recently open about Teigen’s struggles with alcohol.

In another Cosmo interview, the Smirnoff vodka spokeswoman admitted she was “point blank, just drinking too much”.

Teigen said her drinking began to get out of control when alcohol was readily available at events and award shows as a celebrity.

In response to the problem, her soul-crooning husband said the couple discussed everything on their minds and were always honest with each other.

“Whenever she sets her mind to anything, I always tell her, ‘I want to support you and help you do it’.”