Objective: The conflicting results of the previous studies regarding the serum cortisol through the menstrual cycle warranted further research. We aimed to detect the cortisol levels in the follicular and luteal phases of healthy menstruating women.
Materials and methods: A literature search was conducted by two independent authors according to PRISMA criteria over PubMed, Web of Science and Psych-Info to retrieve the articles published in English from 1990 until 2020 and containing the keywords, Cortisol, Menstrual, Follicular, or Luteal. The quality assessment of the articles/studies was done using the CONSORT and STROBE checklists. The risk bias was assessed by two independent authors using Cochrane risk-bias assessment tool.
Results: Twenty-eight (28) articles were included in this meta-analysis. The cortisol levels were significantly higher in the studied-participants' follicular phase compared to the luteal phase (p<0.01). The cortisol levels sub-analysis showed a significant effect of plasma cortisol over the salivary cortisol (p=0.04). The cortisol assay time showed a significant effect of the morning cortisol over the afternoon cortisol (p=0.005).
Conclusions: This meta-analysis found the cortisol levels were significantly higher in the studied-participants follicular phase compared to the luteal phase. The cortisol sub-analysis showed a significant effect of plasma and morning cortisol over the salivary and afternoon cortisol, respectively.