reproductive health

During pregnancy, women’s biological age accelerates, and this is partially reversed after childbirth. A review published in the journal Trends in Endocrinology & Metabolism suggests that closely spaced pregnancies may prevent the body from recovering fully and could lead to the accumulation of changes associated with biological ageing, with potential long-term consequences for maternal health. Although further studies are still needed to test this hypothesis, the authors suggest that the time elapsed between pregnancies could be a significant factor in women’s ageing.

Although menopause is a part of the lives of millions of women—accounting for about one-third of their lives in total—it remains one of the least-studied stages of women’s health. With up to 72 associated symptoms, there are still many unanswered questions about many of them and the impact of treatments. We spoke with experts to find out which questions remain unanswered.

A study has analysed structural changes in the female brain during the three main hormonal transitions: puberty, pregnancy and the menopause. To do this, using longitudinal neuroimaging – which records images of the brain over time – the researchers compared women transitioning from one hormonal phase to another with participants currently in those hormonal phases – more than 1,000 women in total. The results, published in Nature Communications, show that the transitions of puberty and pregnancy lead to a reduction in cortical grey matter, whilst women going through the menopause did not show a significant decrease in either cortical grey matter or total brain volume.

A study published in the journal Cell Host & Microbe analysed endometrial samples from 149 women aged between 20 and 45 who were undergoing treatment for infertility. The younger patients had a significantly higher abundance of a beneficial bacterium called Lactobacillus gasseri, the presence of which decreased with age. Furthermore, pregnant women had a higher abundance of these bacteria in the endometrium. In mouse models, older animals showed higher rates of embryo implantation when treated with L. gasseri derivatives. Despite these findings, the authors emphasise that further research is needed and warn women against self-medicating with over-the-counter L. gasseri products, as their effectiveness in treating infertility has not been validated.

A Spanish study rules out men’s lifestyle habits as an explanation for geographical differences in semen quality. The findings, presented at the annual congress of the European Society of Human Reproduction and Embryology (ESHRE), the abstract of which is to be published today in the journal Human Reproduction, are based on data from 386 men who attended seven assisted reproduction centres across the country between June 2024 and December 2025. They answered questions about their lifestyle habits (physical activity, tobacco use, alcohol consumption, coffee intake, etc.), their place of residence and their body mass index, amongst other factors. Semen quality was higher among men from northern Spain, even though lifestyle habits were similar across all regions, suggesting that differences in quality may be due to exposure to environmental pollutants, says the lead author.

Between 1990 and 2023 in Spain, cases of infertility among women aged between 35 and 49 rose from around 975 cases per 100,000 women in this age group to 2,226 cases per 100,000, figures that are below the European average. Overall, this age-adjusted prevalence rose in all regions of the world during the same period. The study has been published in The Lancet Obstetrics, Gynecology, & Women’s Health.

A systematic review with a meta-analysis published in The Lancet Obstetrics, Gynecology, & Women’s Health concludes that there is insufficient evidence that most complementary treatments for in vitro fertilization (IVF) improve fertility in patients undergoing this procedure. Some of these techniques involve introducing platelet-rich plasma into the uterus or ovaries, administering a lipid infusion into the bloodstream, administering corticosteroids, or performing preimplantation genetic testing to detect aneuploidies—that is, abnormalities in chromosome number. According to the study, which included 85 clinical trials, there is only evidence—albeit of low quality—suggesting a possible benefit from three treatments: EmbryoGlue—a method of embryo transfer containing hyaluronic acid—endometrial scraping, and physiological intracytoplasmic sperm injection—a technique for selecting sperm.

A team in China has studied the ability of a test to detect the human papillomavirus (HPV)—responsible for the vast majority of cervical cancers—in menstrual blood from more than 3,000 women. The results indicate that the test is comparable to current screening performed in medical offices. According to the researchers, “Using menstrual blood for HPV testing is practical and non-invasive, allowing women to collect samples at home and thus potentially offering a practical way to expand access to screening.” The study is published in The BMJ. 

Around 15% of recognized pregnancies end in miscarriage, and it is estimated that almost half of all conceptions are lost in early stages, without people even realizing it. Now, a team from the United States and Denmark has analyzed data from more than 139,000 embryos from in vitro fertilization of nearly 23,000 couples and has found several genetic variants associated with a higher risk of miscarriage. Many of these are associated with meiosis, a key cell division process in sex cells. The authors, whose study is published in Nature, acknowledge that the new data will not allow for a precise estimation of individual risk, because the most important factors remain age and environmental elements.

The use of hormonal contraceptives is associated with a small increase in the risk of breast cancer—one additional case of cancer for every 7,752 women who use these drugs—according to a Swedish study. The risk varies depending on the type of hormones administered, and is slightly higher with the use of contraceptives containing desogestrel. The study, published in JAMA Oncology, analyses data from a national registry between 2006 and 2019, with more than two million women aged between 13 and 49.