Having winged bean leaves in large amounts can cause birth defects and liver toxicity caused due to high doses of Vitamin A. But when had in regular portion sizes, it is an excellent source of fiber, Vitamin C, Vitamin A and minerals. During pregnancy, the fiber helps to relieve constipation in expecting mothers. Vitamin C reduces the risks of complications of a high risk pregnancy, known as pre-eclampsia. Vitamin A, in the right amounts, is essential for expecting mothers because it helps with postpartum tissue repair. It also helps maintain normal vision and fight against infections.