Does my high body weight increase my baby's chances for birth defects?

Yes and no. Not birth defects, but certanly some problems. As well as you. You can develop high blood pressure and diabetes related to a pregnancy, and complications to your child with it will increase as well. You baby could be prone for macrosomia, difficult delivery, probably c-section, possible hypoglycemia, and many others in the future.
According to the. Widely-publicized charge study: http://www. Medicalnewstoday. Com/articles/243911.Php., there is a " strong association" of maternal metabolic conditions (obesity, diabetes & hypertension) & ⬆ risk in offspring of autistic spectrum disorders & other neurodevelopmental disorders, not a cause & effect. Congenital anomalies are ⬆ed if maternal diabetes is poorly controlled. Just take care of yourself.
Possibly. If you have early diabetes because of your weight then this can cause birth defects.