Introduction. Progesterone is a hormone that favors maintaining pregnancy. It is the protagonist of the physiopathology of preterm labor. In this sense, a systematic review is proposed to demonstrate the usefulness of natural micronized progesterone in mitigating the harmful effects of preterm labor. Methodology. A systematic review in which the terms "MeSH" and "No - MeSH" were used. The "Publish or Perish" program was used, as well as databases, such as: Medline, PubMed, Embase, Clinical Key, Cochrane Library, Scopus, and Google Scholar. Review and meta-analysis articles, original articles (preliminary or complete publications), congress summaries, published seminars, textbooks, regional hospital protocols and national consensuses were included, in which each author individually assessed each article and applied the CASPE tool. Results. It was not possible to find concise international guidelines on using micronized progesterone for the threat of preterm labor (PTL) in literature. According to what the authors analyzed, for the mitigation of labor it is generally recommended the use of natural micronized progesterone in 100 to 400 mg/day capsules orally or 100 to 200 mg every 12 to 24 hours through the vagina. From week 16 to week 36 of pregnancy orally and from week 24 to 34 through the vagina. Discussion. Using micronized progesterone has demonstrated mitigating complications subsequent to preterm labor. However, there is no consensus on dosage and routes of administration. Added to the above, the analyzed studies may contain biases, reason why using this medication is left to the physician's discretion. Conclusions. Natural micronized progesterone can be used to mitigate preterm labor according to the articles the authors analyzed throughout the review. However, more studies are needed to validate this hypothesis.