It is recommended to avoid taking D-mannose supplements while pregnant, as there is not enough data to support its safety during pregnancy. However, cranberry juice is a good choice among the supplements mentioned for preventing urinary tract infections. It is important to note that cranberry juice may increase blood sugar levels, which could be a concern for pregnant women with gestational diabetes. Capsules of cranberry are available as an alternative to reduce this side effect. In studies where cranberry was shown to be effective for pregnant women, they took the supplement three times a day.