American pop singer Ashlee Simpson has hit out at reports that she is desperate to lose her baby weight, insisting her main concern is the health of her child.

The US tabloid National Enquirer reported earlier this week that the singer had broken down into tears after learning she had gained more weight than is considered healthy, reports contactmusic.com.

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The publication said that Simpson had bought several pairs of size-zero jeans from the Los Angeles shop Planet Blue to give herself an incentive to shed her post-pregnancy pounds.

"My doctor says I am right on target with my weight gain and I have not been to Planet Blue in at least two years. I love my maternity jeans and my stretchy tops," she posted on her MySpace blog on Friday.

She added: "Carrying a child is the most inspiring, emotional, amazing experience of my life. My weight and my pant size are the absolute last things I am concerned about.

"I am only concerned with having a healthy pregnancy and a healthy baby. People who talk and judge pregnant women's weight need to get a life."

Simpson is said to be expecting her first child with pop band Fall Out Boy bassist husband Pete Wentz this October.