In a word, hormones. They hit everyone differently, so your lack of desire definitely doesn’t mean you (or your sister) are weird. Plus, you're probably experiencing pregnancy symptoms (vomiting, super-sore boobs, so-tired-you-could-croak) that keep you from feeling frisky. Your sister also might be remembering the horny days of her second trimester, when hormones shift, nausea and fatigue fade, and blood increasingly flows to all the right places. Our advice: Even if you’re not up for sex, try to stay emotionally connected with your husband. Tell him how you’re feeling, be affectionate in other ways...and promise him some hot monkey love as soon as you’re feeling better.