Meta-Analysis
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Meta-Anal. Feb 28, 2022; 10(1): 37-45
Published online Feb 28, 2022. doi: 10.13105/wjma.v10.i1.37
Leptin levels in women with unexplained infertility: A systematic review and meta-analysis
Abdullah Abdulslam Abdullah, Musa Ahmed, Adesina Oladokun
Abdullah Abdulslam Abdullah, Musa Ahmed, Department of Reproductive Health Sciences, Pan African University Life and Earth Sciences Institute, University of Ibadan, Ibadan 119, Oyo State, Nigeria
Abdullah Abdulslam Abdullah, Department of Biomedical Sciences, Faculty of Veterinary Sciences, University of Gadarif, Gadarif 208, Sudan
Musa Ahmed, Department of Veterinary Surgery, Faculty of Veterinary Medicine, AL-Salam University, Al-Fulla 209, West Kordofan, Sudan
Adesina Oladokun, Department of Obstetrics and Gynecology, Department of Epidemiology, University College Hospital, Ibadan 119, Oyo state, Nigeria
Author contributions: Abdullah AA, Ahmed M, and Oladokun A conceived and designed the review, developed the search strings, screened and selected the studies, and drafted the manuscript, and Oladokun A rigorously reviewed the manuscript; Abdullah AA is the guarantor of the review; Abdullah AA and Ahmed M extracted the data, evaluated the quality of the studies, and carried out analysis and interpretation.
Conflict-of-interest statement: The authors declare no potential conflict of interest concerning the research, authorship, and/or publication of this article.
PRISMA 2009 Checklist statement: The authors have read the PRISMA 2009 Checklist, and the manuscript was prepared and revised according to the PRISMA 2009 Checklist.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Abdullah Abdulslam Abdullah, MSc, Academic Research, Lecturer, Department of Reproductive Health Sciences, Pan African University Life and Earth Sciences Institute, University of Ibadan, Ibadan 119, Oyo State, Nigeria. bahlol32029@gmail.com
Received: November 22, 2021
Peer-review started: November 22, 2021
First decision: December 10, 2021
Revised: December 17, 2021
Accepted: January 27, 2022
Article in press: January 27, 2022
Published online: February 28, 2022
Processing time: 97 Days and 16.5 Hours
Abstract
BACKGROUND

Unexplained infertility (UI) is usually used for any heterosexual couple who failed to have a successful clinical pregnancy without identifying clear causes after they undergo all standard fertility tests. Evidence shows that leptin is one of the most accurate biomarkers for UI. Nevertheless, conflicting results regarding leptin levels in women with UI have been reported.

AIM

To find the serum leptin levels in women with UI.

METHODS

All studies written in English and conducted before April 30, 2021 from PubMed/MEDLINE, Embase, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, Google Scholar, OpenGrey, OATD, and the infertility conference abstract were included. Studies were found eligible if they provided the mean and standard deviation of leptin for the case group and control group. The quality assessment of individual studies was evaluated using the Joanna Briggs Institute Quality Assessment Tool. Data synthesis and statistical analysis were done using STATA software version 16.

RESULTS

A total of 378 studies were reviewed, and just six studies that fulfilled the eligibility criteria were included in this meta-analysis. The pooled result showed that leptin levels were significantly higher in women with UI compared to fertile women, with a standardized mean difference of 0.97 (95% confidence interval: -0.49-2.43). However, heterogeneity across studies was highly significant (P < 0.00001; I2 = 98.8%).

CONCLUSION

The results of this study suggest that leptin levels are elevated in women with UI compared with fertile women; hence, leptin could be a potential biomarker for UI in women, and it may be useful for identifying women with a high risk of infertility.

Keywords: Leptin; Meta-analysis; Serum level; Unexplained infertility; Women

Core Tip: A comprehensive systematic review and meta-analysis was conducted to find the serum leptin levels in women with unexplained infertility. Six studies were included in this meta-analysis, after passing all quality checkups. The pooled result showed that leptin levels were significantly higher in women with unexplained infertility compared to fertile women, with a standardized mean difference of 0.97. Leptin could be a potential biomarker for unexplained infertility in women, and it may be useful for identifying women with a high risk of infertility.