I'm 12 and, when I laugh too hard, sometimes I wet myself. It's really embarrassing and I don't know how to stop it. Is there something wrong with me or is this normal? Chelsea, via email Even though you feel embarrassed, it might help to know that this is a very common problem, especially for us girls. It's most likely a "mechanical" problem. The bladder sits in your pelvis, just in front of your uterus. Your kidneys filter blood to remove waste and what's left is urine - which travels down into your bladder for storage. When the bladder's full, it gives your brain a signal to pee. The opening of the bladder into the urethra (a tube that transports urine out of the body –- its opening is just above your vaginal opening) is kept tightly closed by muscles that you learn to control when you toilet train as a toddler. Sometimes, these muscles get weak (after women have given birth, or just because of a general lack of exercise and muscle tone, or after gaining a lot of weight), and a problem, like an infection, makes the bladder inflamed and therefore harder to control. In rarer circumstances, there could be a nerve-muscle coordination problem. If this is happening regularly, it's worth getting a check-up from your doctor to rule out a urine infection or other condition. Meanwhile, you can help yourself by doing lots of pelvic floor exercises. To do these, squeeze your pelvic muscles very tightly (as though you’re trying to stop yourself from weeing), hold for 10 seconds, then relax. Do about 100 a day - you can do these when you're watching telly, sitting in class, having lunch - no one can see you doing them! And whatever you do, never stop laughing!