Leaking clear, creamy-white or yellowish discharge from your breasts is a sign that your body is prepping to breastfeed your baby. It tends to happen toward the end of the third trimester, but can occur anytime after five or six months. The fluid you see is called colostrum, which is a precursor to the real milk you'll start producing a few days after delivery. Colostrum is high in protein and contains antibodies that protect your baby against infection during his first few days in the real world. You won't be able stop the leakage, but you may notice that it becomes heavier when your breasts are stimulated (like during sex), which triggers the letdown reflex. If the discharge makes you uncomfortable or dampens your clothing, try wearing some thin nursing pads in your bra.
However, if the discharge starts to look bloody, you should give your doctor a call. Many times this is nothing to worry about; it's caused by the major changes your milk ducts are undergoing as they prepare for lactation. In most cases it clears up after delivery and doesn't interfere with your ability to breastfeed. If it doesn't subside within a few months after your baby is born, your doctor will probably do some tests to find the cause. But before you start worrying, know that 90 percent of persistent bloody discharge is caused by either an infection or some kind of benign growth -- not cancer.