Jessica Simpson defends pregnant nudity for Elle

Appearing Tuesday on Ryan Seacrest's radio show, Jessica Simpson defended her decision to go nude for the April cover of Elle.

"They didn't even ask me to do that," she said. "It was my idea. It kind of just seemed a natural thing for me to do.

"I'm like 170 pounds and I wanted to pose nude," she said. "I try to be like 110 pounds. It's funny to be at your heaviest and feel the most confident. I just take such pride in being a mom! I just love my body more than ever now."

Meanwhile, on Monday's "Tonight Show," Simpson said she's only having one child, despite the size of her bump. "No, it's not twins. I know it looks like it," she told Jay Leno.

The singer and "Fashion Star" mentor, who has an affinity for wearing high-heeled shoes, told Leno that her current condition "is a lot of weight to carry on six inches!" adding that she was "waddling at this point."

Simpson, 31, also explained that she's waiting to lose her baby weight before marrying her fiance, former San Francisco 49ers tight end Eric Johnson, with whom she became engaged in November 2010. "I want him to be my husband so bad," she said. But, "I do still want to wear the pretty gown, so I have to wait."

The baby girl is due this spring. "Labor is really going to hurt," Simpson said. "I have so much respect for my mom and all the women across the world."