Oxidative stress (OS), a state characterized by an imbalance between
pro-oxidant molecules including reactive
oxygen and
nitrogen species, and
antioxidant defenses, has been identified to play a key role in the pathogenesis of
subfertility in both males and females. The adverse effects of OS on sperm quality and functions have been well documented. In females, on the other hand, the impact of OS on oocytes and reproductive functions remains unclear. This imbalance between
pro-oxidants and
antioxidants can lead to a number of reproductive diseases such as
endometriosis,
polycystic ovary syndrome (PCOS), and unexplained
infertility.
Pregnancy complications such as
spontaneous abortion, recurrent pregnancy loss, and
preeclampsia, can also develop in response to OS. Studies have shown that extremes of
body weight and lifestyle factors such as cigarette smoking, alcohol use, and recreational drug use can promote excess
free radical production, which could affect fertility. Exposures to
environmental pollutants are of increasing concern, as they too have been found to trigger oxidative states, possibly contributing to
female infertility. This article will review the currently available literature on the roles of reactive species and OS in both normal and abnormal reproductive physiological processes.
Antioxidant supplementation may be effective in controlling the production of ROS and continues to be explored as a potential strategy to overcome reproductive disorders associated with
infertility. However, investigations conducted to date have been through animal or in vitro studies, which have produced largely conflicting results. The impact of OS on assisted reproductive techniques (ART) will be addressed, in addition to the possible benefits of
antioxidant supplementation of ART
culture media to increase the likelihood for ART success. Future randomized controlled clinical trials on humans are necessary to elucidate the precise mechanisms through which OS affects female reproductive abilities, and will facilitate further explorations of the possible benefits of
antioxidants to treat
infertility.