This chapter reviews data highlighting the vulnerability of obese women to multiple micronutrient deficiencies. It summarizes the evidence supporting the effectiveness of nutrition interventions at preventing key birth outcomes among obese pregnant women. Increased body mass index (BMI) in non-pregnant women is associated with decreased serum folate, ascorbic acid, vitamin E, total carotenoids, and selenium in a variety of populations. With the poor micronutrient status of obese women of childbearing age, and potentially the same relationship in obese pregnant women, it is critical to understand whether micronutrient interventions could positively impact birth outcomes in obese pregnancy. Several high-quality observational studies of birth defects, pre-eclampsia may provide additional insight into whether micronutrient supplementation may reduce the likelihood of poor outcomes among obese pregnant women. Future rigorous observational studies exploring a wide range of micronutrients and risk of poor outcomes of women with high pre-pregnancy BMIs will add to the evidence base.