The ovarian cycle is regulated by internal circadian rhythms rather than external processes, says a study published in Science Advances. Using menstrual cycle data from some 3,000 women in Europe and North America, the authors add that the influence of the lunar cycle on women's menstrual cycle is weak, but significant.
A French study involving more than 100,000 women has found a link between long-term use of some progesterone hormone analogues - used for contraception or hormone replacement therapy - and an increased risk of developing meningioma, a generally benign type of brain tumour. The results are published in The BMJ.
Sperm from older fathers are more likely to pass on new mutations that would cause congenital disorders to their babies, while other mutations are independent of paternal age, says a study published in Genome Biology and Evolution. The team analysed the frequency of ten FGFR3 gene variants in semen samples from anonymous donors aged 23-59 years in Austria. Two pathogenic mutations of this gene do occur more frequently in older fathers: those associated with achondroplasia and with thanatophoric dysplasia, a rare and very fatal disease. Other mutations have no correlation with paternal age and may occur in the testes before sexual maturation, according to the study.
At an informative meeting organized by the Science Media Centre Spain, the coauthor of a paper published this week in the journal Cell discussed his findings with journalists. Although the study was conducted with mice, he is confident in being able to analyze human eggs to see if his conclusions could explain the loss of fertility that occurs in women with age.
An international team, led by a Spanish group, has published the mechanism that allows immature egg reserves (oocytes) to survive for many years, up to almost half a century in the case of humans. The research studies how oocytes are affected by protein aggregates similar to those that damage other cells such as neurons and can cause neurodegenerative diseases such as Alzheimer's disease. The finding of how these egg reserves are kept healthy may help to understand some causes of infertility. The results are published in the journal Cell.
A team of researchers has demonstrated how a non-invasive ultrasound technique can increase the movement of human sperm in the laboratory by up to 266%. Using microfluidic droplets to evaluate individual sperm cells, which had not been done before, they found that ultrasound exposure induced movement in immobile sperm and improved swimming speeds in mobile ones. The work is published today in the journal Science Advances.
An early first menstrual period (menarche) - compared with the average of 13 years - is associated with an increased risk of type 2 diabetes in women under the age of 65 and also with an increased risk of stroke among those living with diabetes, says a study published in BMJ Nutrition, Prevention & Health. The research analyses data from a national health survey in the US, focusing on women aged 20-65 between 1999 and 2018.
A review of 25 studies conducted over nearly 50 years has found an association between insecticide exposure and lower sperm concentration. According to the authors, "insecticides are a public health concern for all men, who are exposed mainly through consumption of contaminated food and water". The results are published in the journal Environmental Health Perspectives.
Spermidine is a naturally occurring compound that has been linked to increased longevity in some organisms. New research shows that supplementation with this compound improves oocyte quality and fertility in older female mice. If its action and safety in humans is confirmed, the authors argue that it could serve as a therapeutic strategy to "improve the reproductive outcome of older women, either through natural pregnancy or assisted reproductive technologies". The results are published in the journal Nature Aging.
We compared semen analyses of 45 patients before and after mild covid-19 infection. We found a significant decrease in sperm volume, sperm concentration, total and progressive motility and vitality after infection, and that these effects may be long-term.