Jessica Simpson has dismissed rumours she is carrying twins.

The singer is expecting her first child with fiance Eric Johnson and she announced her pregnancy in October (11) after weeks of speculation about her growing baby bump.

Simpson has now revealed she won't find out whether she is having a boy or a girl until the birth, as she can't trust herself to keep the news quiet, but she does know it is not a double bundle of joy.

She tells radio host Ryan Seacrest, "I'm a loudmouth. There's no way (I will find out the baby's gender)... I eventually want both (a boy and a girl) so I'll be happy with either one, but it's definitely not twins."