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After completion of this article, the reader should be able to state that the causes of spontaneous and recurrent abortion are multifaceted, however, some of the causes may be preventable and also explain that the role of oxidative stress during pregnancy and adverse pregnancy outcomes has a basis in pathophysiology, although the role of oxidative stress and the treatment of oxidative stress during or before pregnancy remains speculative.

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Hypochlorous acid (HOCl) is generated by myeloperoxidase, using chloride and hydrogen peroxide as substrates. Here we demonstrate that HOCl alters metaphase-II mouse oocyte microtubules and chromosomal (CH) alignment which can be prevented by melatonin. Metaphase-II mouse oocytes, obtained commercially, were grouped as: control, melatonin (150, 200nmol/mL), HOCl (10, 20, 50, and 100nmol/mL), and HOCl (50nmol/mL) pretreated with 150 and 200 nmol/mL of melatonin. Microtubule and CH alignment was studied utilizing an indirect immunofluorescence technique and scored by two observers. Pearson chi-square test and Fisher's exact test were used to compare outcomes between controls and treated groups and also among each group. Poor scores for the spindle and chromosomes increased significantly at 50nmol/mL of HOCl (P<0.001). Oocytes treated with melatonin only at 150 and 200 nmol/mL showed no changes; significant differences (P<0.001) were observed when oocytes exposed to 50nmol/mL of HOCl were compared to oocytes pretreated with 200 nmol/mL melatonin. Fifty percent of the oocytes demonstrated good scores, both in microtubule and CH alterations, when pretreated with melatonin at 150 nmol/mL compared to 0% in the HOCl-only group. HOCl alters the metaphase-II mouse oocyte spindle and CH alignment in a dose-dependant manner, which might be a potential cause of poor oocyte quality (e.g., in patients with endometriosis). Melatonin prevented the HOCl-mediated spindle and CH damage, and therefore, may be an attractive therapeutic option to prevent oocyte damage in endometriosis or inflammatory diseases where HOCl levels are known to be elevated.

Here we show that hydroxyl radical (•OH) generated through the Fenton reaction alters metaphase-II mouse oocyte microtubules (MT) and chromosomal alignment (CH). Metaphase–II mouse oocytes, obtained commercially, were grouped as follows: control, hydrogen peroxide (H2O2), Fe (II), and combined (Fe (II) + H2O2) treatments. After 7–10 minutes of incubation, at 37 °C, MT and CH were evaluated on fixed and stained oocytes and scored by two blinded observers. Pearson Chi-square test, Fisher's Exact test were used to compare outcomes between controls and treated groups, and also amongst each group. Our results showed that poor scores for MT and CH increased significantly in oocytes treated with combination of H2O2 and Fe(II) (p <0.001); oocytes treated with H2O2 alone or Fe(II) alone showed no or little changes compared to control. Comparison of oocyte groups that received increasing concentrations of H2O2 and fixed amount of Fe (II) showed that 70 – 80 % demonstrated poor scores both in MT and CH when pretreated with 5 μM H2O2, and increased up to 90–100% when treated with 10–20 μM of H2O2. Hydroxyl radical generated by H2O2 driven Fenton reaction deteriorates the metaphase-II mouse oocyte spindle and CH alignment, which is thought to be a potential cause of poor oocyte quality. Thus, free iron and/or ROS scavengers could attenuate the •OH-mediated spindle and chromosomal damage, thereby serving as a possible approach for further examination as a therapeutic option in inflammatory states.