Increased vaginal discharge is just another side effect of pregnancy. When you're expecting, your vagina secretes more mucus than usual, especially in the third trimester when it's preparing for labor. It's totally normal to have discharge that's clear to white or yellowish white with no strong odor. Since the discharge can be heavy at times, you may want to wear a pad (never use tampons while you're pregnant).
However, if you also have symptoms like burning and bad itching along with the discharge, it could be a yeast infection, which you're more prone to during pregnancy. If it's a yeast infection, the discharge may also be thicker, with more of a cottage cheese consistency. Though you can treat yeast infections yourself with over-the-counter meds, it's a good idea to see your doctor to make sure it's not something else. These symptoms could also indicate other infections like bacterial vaginosis (BV) or trichomoniasis, which can cause preterm labor if left untreated during pregnancy. Greenish or yellowish discharge can also be signs of some sexually transmitted diseases, which your doctor should check out. If your discharge seems a lot heavier or different than normal (especially if it's pinkish, brownish, or bloody), you should let your doctor know right away. This could be a sign of miscarriage or preterm labor, especially if it's accompanied by strong abdominal or lower-back pain.