Jessica Simpson reportedly won't marry until she loses her baby weight.

The 170lb singer-turned-fashion designer - who is expecting a baby girl with fiancé Eric Johnson - apparently refuses to walk down the aisle until she has regained her figure.

A source said: ''She hates the idea of getting into a wedding dress until she's given birth and lost the baby weight.''

The delay is also said to have been caused by disagreements between Jessica, 31, and her football player beau over a pre-nuptial agreement.

Talking to America's OK! magazine, the insider claimed: ''She loves him, but there are several issues that haven't been resolved yet.

''Jessica wanted a prenup, but Eric was upset at the idea of putting one in place. So they spent months negotiating and bickering about it, which contributed in no small way to the wedding being delayed.''

Meanwhile, the 'Fashion Star' mentor is mentally preparing herself to deliver a big baby.

She told Elle magazine: ''She's in the 90th percentile of weight right now, so she's a big un. She's going to be a very big baby, but I guess that's what I get for letting a baller knock me up.''

But she refuses to let fear get the better of her. She added: I'm more anxious than afraid. I have not been afraid the whole time. I figure if all these women all around the world can do it, I can do it.''