RESUMEN
RESEARCH QUESTION: Does systemic oxidative stress occur during the early follicular phase of the menstrual cycle in infertile women with minimal (stage I) or mild (stage II) endometriosis? Are serum oxidative stress markers during the early follicular phase of the menstrual cycle good predictors of successful gestation in these women who undergo ovarian stimulation for intracytoplasmic sperm injection (ICSI)? MATERIALS AND METHODS: A pilot study (prospective case-control study) was conducted in a University Hospital. Serum samples were obtained during the early follicular phase of the natural cycle preceding ovarian stimulation for ICSI of infertile women (with and without stage I and II endometriosis, the latter having male factor infertility). Total hydroperoxides (FOX1), malondialdehyde, advanced oxidation protein products, reduced glutathione, superoxide dismutase, total antioxidant capacity (TAC), 8-hydroxy-2'-deoxyguanosine (8OHdG) and vitamin E were analysed in serum from 35 women with stage I or II endometriosis and 60 control women. The accuracy of oxidative stress markers for predicting clinical pregnancy and live births was determined by receiver operator characteristic curves. RESULTS: Women with stage I and II endometriosis showed lower serum 8OHdG concentrations (16.02 ng/ml) compared with the control group (22.08 ng/ml). The best predictor for clinical pregnancy and live births was TAC, whereas FOX1 was the best predictor of clinical pregnancy in the control group. CONCLUSIONS: Infertile women with stage I and II endometriosis present systemic oxidative stress during the early follicular phase of the menstrual cycle. Some oxidative stress markers were good predictors of clinical pregnancy and live births after ICSI. Serum TAC was predictive of clinical pregnancy and live births after ICSI in women with stage I or II endometriosis.