Sex causes no problems during an uncomplicated pregnancy, and sexual interest often changes during different phases of a pregnancy.
Working or going to school, if it isn't too physically demanding, is usually fine during pregnancy. Scale back if you're becoming too worn down as your pregnancy progresses. Talk to your doctor or midwife if you are at risk for preterm labor.
Travel is usually a safe choice until later pregnancy. Talk to your doctor or midwife if you have any concerns. During your third trimester, it's best to stay within a few hours of a hospital, in case of sudden changes that need medical attention.