The study was conducted as a case-control study survey between May 2016 and February 2017 on 156 infertile women (78 women with endometriosis and 78 controls) that attended in Infertility Clinic of Arash Hospital in Tehran, Iran.
During the period of the study, all infertile women who undergone diagnostic laparoscopy were allocated. Based on the laparoscopy results, those women with abnormalities other than endometriosis (eg. endometrial hyperplasia, leiomyoma, and other gynecological cancer) were excluded from the study. Participants were divided into two groups: a case group consisted of 78 women with endometriosis for whom the disease was confirmed by laparoscopy and histology examinations, and a control group consisting of 78 infertile women with a normal pelvis. A control group was selected at the same time as the case group. Controls were selected randomly matched on age, education, and duration of infertility.
Eligibility criteria for inclusion in the study were including age between 18 and 45 years, absence of the history of chronic diseases or mental disorder according to self-report of women, Iranian race, Non-occurrence of bad events in the 12 months ago (e.g. death or illness of family members or close friends, financial difficulties, and etc.)
Ethical approval for the study was obtained from the Regional Ethics Committee at Tarbiat Modares University of Medical Sciences (IR.TMU.REC.1395.358). All women voluntarily participated and signed informed consent.
During the first visit, the weight and height of all women recoursing to the infertility clinic are measured. Body Mass Index (BMI) is calculated as weight divided by height squared (kg/m2).
A socio-demographic checklist including questions about socio-economic status (such as age, educational level, occupational status, income, and smoking history) was completed. The following, questions were asked about menstrual and reproductive characteristics (such as menstrual pattern, cycle regularity, menstrual duration, amount of menstrual bleeding, length of the menstrual cycle, premenstrual spotting, menarche age, presence of dysmenorrhea, dyspareunia and chronic pelvic pain, gravidity, parity, history of using contraception).
Participants were asked to report their exercise times/week. Based on their response, the participants’ physical activity was determined at three levels: low (less than 1 h per week), moderate (2–3 h per week), and high physical activity (more than 3 h per week).
A semi-quantitative 147-item FFQ was applied to obtain dietary information. This questionnaire included a list of dietary items (with standard serving measures) commonly consumed by Iranians. The Persian version of FFQ has previously been evaluated for both reliability and validity [16]. The participants were asked to report their usual food intake during the previous year on a daily, weekly, monthly and yearly basis; all these were converted to daily intakes. Portion sizes of the consumed food were transformed to grams by using domestic measurement.
All consumed food items were analyzed for their energy and nutrient components by a nutrient database (Nutritionist 4, Mosby Nutritract software, and ver.7.0, N-Squared Computing, Salem, OR, USA).
For assessment of dietary sources of melatonin, we considered food rich of tryptophan including dairy product, nut (peanut, almond, pistachio, and walnuts), fruit (banana, apple, kiwi, peach, and strawberry, orange) and meat (red meat, pultatory, and fish).
Multiple aspects of SQ during the previous month were assessed using the valid and reliable Persian version of the Pittsburgh Sleep Quality Index (PSQI) [17]. This questionnaire contains 19 items in seven categories (sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction) on a scale from 0 to 3; so the total score of PSQI is from 0 to 21. A total score higher than 5 identifies poor SQ and scores lower than 5 show the absence of sleep disorder.
Statistical analysis was performed using Statistical Package for Social Science (version 16). To check the variables’ normality, Kolmogorov–Smirnoff’s (KS) test was run. Comparisons between two groups were done using Independent Samples T-Test, Mann-Whitney’s test (MW), Chi-square tests, and logistic regression model.