The role of placental aging in adverse pregnancy outcomes: A mitochondrial perspective

Exposure to radon and ambient particle radioactivity during pregnancy and adverse maternal, fetal and perinatal outcomes: The current literature and potential mechanisms

Radon is a colorless, odorless radioactive gas that is naturally occurring in the environment, originating from the decay of uranium that exists in the earth's crust. In addition to lung cancer, radon exposure has recently been associated with hypertension and cardiovascular disease. However, little consideration has been given to radon exposure during pregnancy, even though pregnant people are a more vulnerable population and ionizing radiation is a known risk factor for adverse maternal and fetal outcomes. There is also greater recognition of the potential effect of ambient particle radioactivity. The radioactivity of ambient particles is primarily due to the decay of radon progeny, and thus another source of exposure to radiation due to radon decay. We systematically searched and evaluated the literature and summarized the current evidence on radon and particle radioactivity exposure during pregnancy. While the literature is sparse, we identified eight human studies that address this topic. The accumulated evidence suggests that radon and particle radioactivity may be associated with a range of adverse pregnancy outcomes, including gestational diabetes and hypertension and fetal development. Additionally, we highlight several potential biological pathways by which radon may affect maternal and fetal health. The ubiquity of radon and ambient particle radioactivity exposure, biological plausibility and results of early studies all suggest radon exposure during pregnancy is an important topic that merits further investigation.

Placental Bioenergetics and Antioxidant Homeostasis in Maternal Obesity and Gestational Diabetes

Maternal obesity has been associated with short- and long-term risks of pregnancy-perinatal adverse events, possibly due to alterations of placental mitochondrial bioenergetics. However, several detrimental mechanisms occurring in the placentas of women with obesity still need to be clarified. Here, we analyzed placental mitochondrial features and oxidative environment of 46 pregnancies in relation to pre-pregnancy BMI. Seventeen Caucasian normal-weight (NW) and twenty-nine women who were obese (OB) were enrolled. The protein expression of mitochondrial CypD and electron transfer chain complexes (C) I-V were measured, as well as ATP production and oxygen consumption rates (OCRs). The protein levels of the pro/anti-oxidant enzymes TXNIP, SOD2, and PON2 were also analyzed. Despite no differences in CypD expression, OCRs were significantly lower in OB vs. NW women. Accordingly, ATP synthase (CV) levels and ATP content were decreased in OB women, positively correlating with placental efficiency, suggesting a link between ATP deficiency and placental dysfunction. SOD2 expression negatively correlated with maternal BMI, indicating a possible impairment of antioxidant defenses with increasing BMI. These changes were worsened in 10 OB women presenting with gestational diabetes mellitus. Overall, these results suggest alterations of placental bioenergetics in pregnancies of women with obesity, possibly leading to placental dysfunction and altered fetal development and programming.

Melatonin-mediated actions and circadian functions that improve implantation, fetal health and pregnancy outcome

This review summarizes data related to the potential importance of the ubiquitously functioning antioxidant, melatonin, in resisting oxidative stress and protecting against common pathophysiological disorders that accompany implantation, gestation and fetal development. Melatonin from the maternal pineal gland, but also trophoblasts in the placenta, perhaps in the mitochondria, produce this molecule as a hedge against impairment of the uteroplacental unit. We also discuss the role of circadian disruption on reproductive disorders of pregnancy. The common disorders of pregnancy, i.e., stillborn fetus, recurrent fetal loss, preeclampsia, fetal growth retardation, premature delivery, and fetal teratology are all conditions in which elevated oxidative stress plays a role and experimental supplementation with melatonin has been shown to reduce the frequency or severity of these conditions. Moreover, circadian disruption often occurs during pregnancy and has a negative impact on fetal health; conversely, melatonin has circadian rhythm synchronizing actions to overcome the consequences of chronodisruption which often appear postnatally. In view of the extensive findings supporting the ability of melatonin, an endogenously-produced and non-toxic molecule, to protect against experimental placental, fetal, and maternal pathologies, it should be given serious consideration as a supplement to forestall the disorders of pregnancy. Until recently, the collective idea was that melatonin supplements should be avoided during pregnancy. The data summarized herein suggests otherwise. The current findings coupled with the evidence, published elsewhere, showing that melatonin is highly protective of the fertilized oocyte from oxidative damage argues in favor of its use for improving pregnancy outcome generally.