Jessica Simpson has written a song for her unborn baby, it has been reported.

The star is expecting a girl with her fianc Eric Johnson and she is due to give birth next month. The couple are rumoured to have chosen the name Maxwell for their daughter. Jessica has been putting her musical talents to good use and has penned a special song for the baby.

"Jessica's even written a song called Our Little Maxi, which she sings to her baby at night," a source told In Touch.

The 31-year-old can't wait to meet the new arrival.

However, she is believed to be feeling anxious about the impending birth after her younger sister Ashlee Simpson endured a lengthy labour with her son Bronx in 2008.

"Jessica has no tolerance for pain, so the thought of going through labour scares the bejesus out of her," a source revealed before claiming Jessica may have a scheduled C-section. "She isn't 100 per cent sure, but that's the plan."

Jessica enjoyed a star-studded baby shower over the weekend.

The expectant mother was joined by Ashlee, Jessica Alba and Ellen Pompeo in Los Angeles on Sunday afternoon.

Jessica sparked rumours she has already chosen a name for her baby after she was spotted wearing an M' pendant and has reportedly ordered a host of baby clothes with Maxwell emblazoned on them.