World Health Organization (WHO) states vitamin D deficiency in pregnant women is still high and recognized as a global problem. Vitamin D supplementation can support increasing vitamin D status for pregnant women and babies. This study aims to know the importance of vitamin D during pregnancy and its benefits for pregnant women and their babies. A systematic review of Randomized Controlled Trials (RCT) used PubMed, Science Direct, and Springer Link databases. The determination flow article used the PRISMA diagram. The total number of articles reviewed is four articles. The result has obtained that vitamin D has several benefits if its needs are sufficient during pregnancy, such as reducing the risk of recurrent asthma/wheezing in newborns from mothers with or without asthma, and beneficial in pregnancy with diabetes mellitus. However, the benefits of vitamin D are not proven to change blood pressure at the beginning and middle of pregnancy. Researchers still find inconsistency about the effect of vitamin D on pregnant women if it has compared the results of this article review with another similar research.