Vanessa Lachey is unable to wear her wedding dress for her one-year anniversary because it is “not zipping up”.

The star and Nick Lachey tied the knot on Sir Richard Branson’s private Necker Island in the British Virgin Islands last July.

Vanessa was planning to wear her gown to mark her first year of marriage but has been forced to rethink her plans now she is pregnant.

"My wedding dress was in two pieces with a separate bustier," Vanessa told E! Online."I was thinking of wearing the bustier for our one-year-anniversary.

"That is not happening. That thing is so not zipping up."

Vanessa and Nick are expecting their first child together and also hope to have a baby shower around the time of the anniversary. They have boy and girl names picked out as they don’t know the sex of the baby yet.

"We were thinking about possibly doing a baby shower around our anniversary to celebrate our marriage and the welcoming of our baby," Vanessa said.

The news comes amid reports Nick may miss the birth of his first child as he will be getting back together with boy band 98 Degrees for a reunion tour this summer. However, Vanessa insists no shows are on the cards just yet.

“They broke up about ten years ago and they've always talked about a reunion," she said. "As of now, he will not be on tour."