Yolanda Cabello

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.

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.

The BMJ has published a meta-analysis about weight gain in pregnant women and the risks it poses to their health and that of their babies. According to the study, 68% of pregnancies involve weight gain that is either above or below the recommended level, which is associated with complications such as premature birth, high birth weight, and admission to intensive care. The review included data from 1.6 million women from various regions of the world and different income levels, recorded between 2009 and 2024.

An international team has succeeded in generating fertilisable human eggs from skin cells using a novel technique. According to the authors, the study offers a way to address infertility, although they acknowledge that further research is needed to ensure efficacy and safety before future clinical applications. Of the 82 functional oocytes generated and fertilised, only 9% developed to day 6, when the experiment ended. In addition, the embryos had chromosomal abnormalities. The results are published in the journal Nature Communications.

The relative risk of being born with a major heart defect is 36% in babies conceived using assisted reproductive techniques, such as in vitro fertilisation, compared to newborns not using these techniques, according to a study published in the European Heart Journal. The absolute risk was 1.84% versus 1.15%. The research, which included more than seven million babies born in Denmark, Finland, Norway and Sweden, also shows that the increased risk is especially associated with multiple births, which are more common in assisted reproduction.
 

The sperm of men infected with high-risk genotypes of the human papillomavirus (HPV) suffers more damage from oxidative stress and has a weaker immune response, which can lead to reduced fertility. This is one of the conclusions of a study published in the journal Frontiers in Cellular and Infection Microbiology. The research compared the semen of 20 adults infected with high-risk genotypes, seven infected with low-risk genotypes, and 43 adults without infections.

Un estudio analizó la edad biológica de más de 1.700 participantes utilizando seis relojes epigenéticos diferentes. Los resultados mostraban que cada embarazo individual reportado por una mujer se correlacionaba con un envejecimiento biológico adicional de dos a tres meses. Estos efectos persistían incluso cuando se tenían en cuenta el estatus socioeconómico, el tabaquismo, la variación genética y la urbanidad del entorno de los participantes. El estudio se publica en PNAS. 

A study published in the journal PLOS Medicine concludes that the development and academic outcomes of girls and boys conceived with in vitro fertilisation (IVF) are no different from those of children conceived naturally. The analysis is based on data from two national assessments in Australia, including more than 585,000 children born between 2005 and 2014 (more than 11,000 conceived by IVF). The first assessment measured the physical and emotional and cognitive health of children aged 4-6 years; the second focused on the numeracy and verbal skills of schoolchildren aged 7-9 years.