Mier‐Cabrera 2008

Methods	Randomised controlled trial
Participants	Infertile women with peritoneal endometriosis stage 1 or 2 diagnosed by laparoscopy (n = 36). All participants had fulguration of endometrial implants. Mean age: Treatment group 32.7 ± 2.36; Placebo group 32.7 ± 2.36 Inclusion criteria: women between 25 and 35 years old who had been diagnosed as having peritoneal endometriosis on exploratory laparoscopy, with fertile male partner Exclusion criteria: women who reported having used nutritional supplements during the previous year; who had pelvic inflammatory disease or autoimmune, endocrine or metabolic disorders; or who did not agree to participate or missed a medical visit
Interventions	1. Vitamins C 343 mg + Vitamin E 84 mg: in a bar form, 1 bar a day (n = 18) 2. Placebo (n = 18) Duration of trial was 6 months Follow‐up for up to 9 months after the trial
Outcomes	Live birth (no data available) Pregnancy (no explanation of whether pregnancies were biochemical, clinical or ongoing). "None of the patients became pregnant during the trial. Once the trial ended, patients were followed up for 9 months for a possible pregnancy". The pregnancy rate was 19% (3 of 16) in the supplementation group and 12% (2 of 18) in the placebo MDA, oxidative stress markers obtained during the exploratory laparoscopy
Notes	Consent signed Ethics was approved The study was conducted at the National Institute of Perinatology “Isidro Espinosa de los Reyes” in Mexico City, study dates not reported Funding given as a grant from Consejo Nacional de Ciencia Tecnologia Mexico. Power calculation done. Tried to contact author. Contacted author again 12th February 2013 to ask about clinical pregnancy and live birth. No reply
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Reference was made to the use of 'randomisation codes', and investigators stated, "Thirty‐six participants were randomly assigned". Authors contacted regarding this
Allocation concealment (selection bias)	Unclear risk	Not stated in the paper. Authors contacted regarding this. The response was, "women were randomly allocated depending on the colour of a ball they took out from a container"
Blinding (performance bias and detection bias) All outcomes	Low risk	Women were blinded. The bars were "identical‐looking and tasting bars". Authors contacted regarding this and confirmed that investigators, outcome assessors and clinicians were blinded also. "Randomization codes were unlocked at the end of the study".
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	2 women in the treatment arm dropped out "for personal reasons". ITT not applied
Selective reporting (reporting bias)	High risk	Investigators stated they would collect live birth rates but reported only pregnancy rates
Other bias	Low risk	No other bias found