Nicole Richie insists the hardest part of pregnancy is not knowing whether the baby is a boy or a girl. The socialite is five months pregnant with rocker Joel Madden's first child and the couple has opted not to know the baby's sex, which has become the most difficult part of impending motherhood for Richie. She explains, "We don't know... We're waiting to find out, which has been a lot harder on me than it has on Joel because I'm so nosy, I like to know everything. "If he wasn't at every doctor's appointment, I probably would have found out by now behind his back and not told him. He's been in the room every time, so I haven't had a chance to sneak away and ask the doctor." And knowing the baby's sex isn't the only thing Madden and Richie can't decide on - they also can't agree on a name for their child.