How mothers tolerate their children

Redefining Health-Related Fitness: The Adaptive Ability to Foster Survival Possibilities

Fitness has been dominantly defined in terms of physical conditioning components. Under such definition, males tend to outperform females in strength, speed, aerobic or anaerobic capacity when compared at the same age and training status. However, females have a higher life expectancy, which in humans is related to higher biological fitness. Using the paradox of sex differences in fitness-where males have higher physical fitness but do not have a higher life expectancy-the aim of this opinion paper is to (a) highlight the multidimensionality of fitness, and (b) redefine health-related fitness, drawing on key fitness goals in biology: adaptability and survival. The redefinition of health-related fitness as the "adaptive ability to foster survival possibilities" encompasses synergies across physical, mental, psychological, emotional, social and subjective dimensions, while embracing the diversity of human characteristics, including sex, gender, age, somatotype, vital state, disability, disease and wellbeing, among others.

Efficacy of Corticosteroids in Patients With Recurrent Pregnancy Loss: A Systematic Review and Meta-Analysis

Recurrent pregnancy loss (RPL) represents a complication of pregnancy occurring in 1%-3% of all couples trying to conceive. About 50%-60% of RPL cases remain idiopathic, therefore therapeutic strategies seem empirical and based on unproven evidence. We investigated the efficacy of corticosteroids in women with RPL. We conducted a systematic review and meta-analysis, up to August 2024, in the PubMed, Scopus, and Web of Science databases, including studies on idiopathic RPL women and comparing corticosteroids versus control treatment. Primary outcome was the ongoing pregnancy rate beyond 12 weeks of gestation; secondary outcomes were live birth rate (LBR), stillbirth, birth weight, incidence of preeclampsia and/or gestational diabetes, gestational age at delivery, and fetal abnormalities. Four studies comprising 417 RPL women randomly assigned to steroid or control treatment were included. We found that oral corticosteroids significantly increase the ongoing pregnancy rate beyond 12 weeks of gestation compared to the control group (log OR [odds ratio] = 1.49 [0.32, 2.67], p = 0.01), with high heterogeneity (I2 = 75%), and improve LBR (log OR = 0.9 [0.11, 1.69], p = 0.03), with low heterogeneity (I2 = 0.05%). However, the limited number of studies significantly limits the strength of the findings. Also, the benefit/risk assessment of the use of corticosteroids in early pregnancy for RPL is still unclear.

Pregnancy induced displacement of preexisting microchimeric cells in the absence of maternal B and T cells

Bidirectional exchange of cells between mother and fetus occurs during pregnancy, and persistence of these genetically foreign cells establishes long-term microchimerism in both individuals after parturition. Since women can have multiple pregnancies, and all mothers were once daughters themselves, the microchimeric milieu in each woman could theoretically contain cells from a variety of origins, including from their own mothers as well as their babies from each pregnancy. Interestingly and in sharp contrast to this prediction, we recently showed preexisting populations of microchimeric cells are lost following pregnancy and associated with seeding of new fetal microchimeric cells. Complete loss of preexisting microchimeric cells in this context draws parallels to immunological rejection with synchronized elimination of cells and tissues that express defined discordant antigens. This perspective evaluates this provocative hypothesis regarding pregnancy induced rejection of microchimeric cells, including new experimental data comparing microchimerism levels in mice simultaneously lacking B and T cells before pregnancy, and after parturition with primary and secondary pregnancies.