Congratulations on your pregnancy! Climbing stairs can be a safe form of exercise during pregnancy, even at 15 weeks. However, there are a few things to keep in mind. First, listen to your body and take breaks if you feel tired or dizzy. Second, make sure the stairs are well-lit and have handrails for support. Third, avoid rushing or carrying heavy objects while climbing stairs to prevent falls or strain on your body. If you have any concerns or medical conditions that may affect your ability to climb stairs, consult with your healthcare provider for personalized advice. Remember, staying active during pregnancy is important for overall health, but always prioritize safety and comfort.