Should I lower my insulin doses so it doesn't lower the baby's blood sugar too low?

No. Insulin is a large molecule that does not cross the placenta. Glucose is a small molecule that does cross the placenta. If mom's sugar is high the baby will have to make a lot of Insulin to control fetal blood sugar. If mom's blood sugar stays normal then the baby does not have to work so hard. Use the prescribed amount of Insulin to keep your blood sugar optimized for you and your baby's health.
No. Baby will have low bg if your bg are too high.