Uy, at 39 weeks yan ay very normal talaga, ang baby ay pushing down sa bladder mo na, kaya kahit onting vibration from the motor, parang gusto mo na mag-ihi agad! A few of us went through this last month of pregnancy, at honestly ang motorcycle motion talaga ay nag-trigger ng pressure sa bladder. I'd suggest na mag-pee ka na bago sumakay, at maybe limit mo na ang long rides muna since you're so close to your due date anyway, mas safe din para sa baby. If the feeling becomes intense or you notice anything unusual like pain or bleeding, check with your OB na lang to be sure, pero sa pressure lang yan most likely.