If you suffered from stress incontinence during pregnancy, then you are more likely to have it after the birth too. Women who have had vaginal births are also more likely to develop the problem than those who had c-sections. Assisted vaginal births (when forceps and other devices are used) put you at even greater risk of developing the problem, as does being obese or if you have already had two or more children before your latest child.
In most cases, stress incontinence will start to disappear soon after birth, and within a few weeks or months, it should be gone altogether, or have become an infrequent problem. If you have had stress incontinence however, you are more likely to experience it later on, as you age.
Using a sanitary pad to protect clothes from leaks can help, as can crossing your legs before you cough or sneeze. Kegel exercises can also help to strengthen muscles, and may help the problem, and going to the bathroom as soon as you feel the need to is always a good idea. Avoiding coffee (a diuretic) has been shown to help in some cases too.