Xiaoming Zhou,1 Weiwei Shen,1 Jue Zhu,2 Yichen Chen,2 Jing Zhang2 

1Department of Gynecology, The First Affiliated Hospital of Ningbo University, Ningbo, Zhejiang, 315010, People’s Republic of China; 2Department of Gynecology, Ningbo Women & Children’s Hospital, Ningbo, Zhejiang, 315010, People’s Republic of China

Correspondence: Jing Zhang, Department of Gynecology, Ningbo Women & Children’s Hospital, 339 Liuting Street, Haishu District, Ningbo, 315010, Zhejiang, People’s Republic of China, Tel +86-15867877000, Email jzhang_nbdr@outlook.com

Purpose: To investigate the association between the oxidative balance score (OBS) and endometriosis.
Methods: This cross-sectional study used four cycles of the National Health and Nutrition Examination Survey (NHANES) (1999– 2000, 2001– 2002, 2003– 2004, and 2005– 2006). OBS involved 16 dietary nutrients and 4 lifestyle factors, including 5 pro-oxidants and 15 anti-oxidants. According to weighted quartiles, the OBS was divided into four categories: < 12.54, 12.54– 18.70, 18.71– 24.68, and > 24.68. Endometriosis was diagnosed based on a question from the reproductive health questionnaire. Weighted multivariate logistic analysis was used to investigate the association between OBS and endometriosis. Subgroup analysis was performed based on menstrual regularity and female hormone use.
Results: A total of 5095 women were included, with 1140 (22.37%), 1232 (24.18%), 1224 (24.02%), and 1499 (29.42%) women in the OBS < 12.54, of 12.54– 18.70, of 18.71– 24.68, and > 24.68 categories, respectively. After adjusting age, race, family poverty-to-income ratio (PIR), education level, uterine fibroids, menstrual regularity, oophorectomy, female hormone use, hypertension, dyslipidemia, and steroid drug, a high OBS (> 24.68) was found to be associated with lower odds of endometriosis [odds ratio (OR) = 0.70, 95% confidence interval (CI): 0.50– 0.97, P = 0.033] compared to a low OBS (< 12.54). The similar result was also found in women with irregular menstruation (OR = 0.58, 95% CI: 0.37– 0.91, P = 0.020) and with female hormone use (OR = 0.71, 95% CI: 0.52– 0.98, P = 0.037).
Conclusion: A high OBS was associated with lower odds of endometriosis, especially in women with irregular menstruation and female hormone use.

Keywords: Oxidative balance score, endometriosis, menstruation, female hormones, NHANES