Iron deficiency in mothers during pregnancy can lead to changes in the baby's sex.

New research by Japanese scientists has just shown that minerals in a mother's diet can directly affect the sex of the fetus.

Researchers are increasingly interested in the possibility that maternal nutrition, as well as the impact of environmental toxins, may affect gene activity during the early stages of fetal gonadal development. - Photo: AI

In mammals, biological sex is determined primarily by chromosomes: XY makes males, and XX makes females. A key gene, SRY, initiates testicular formation if activated in an XY embryo. Conversely, if SRY is inactive, ovaries will form.

In a new study, Japanese scientists discovered that SRY can only function thanks to an enzyme called histone demethylase, and this enzyme requires iron to perform its function.

Iron deficiency in the body can impair enzyme activity, causing SRY to be "switched off" even though the chromosomes are XY, leading to the development of ovaries instead of testes.

To test the hypothesis, the research team fed the mother mice an iron-deficient diet for one month before pregnancy and continued this diet for the first two weeks of pregnancy.

The results showed that the mother mice were anemic, and the embryos also exhibited signs of anemia. The majority of the fetuses still developed reproductive organs that matched their chromosomal set.

However, when the research team retested the group of mice with a mutation that weakened the activity of the enzyme histone demethylase, 2 out of 43 XY mice developed female reproductive organs (two ovaries). In contrast, all control mice developed reproductive organs consistent with their genetic sex.

The research team continued to use chelating iron (a drug that reduces iron levels) during the period from day 6 to day 10 of fetal development, the time when sex determination occurs. Of the 72 XY embryos born, 4 had two ovaries, and 1 had both an ovary and testes.

Notably, when the team directly targeted a gene responsible for transporting iron into gonadal cells, they observed a 50% reduction in SRY gene expression. After birth, 6 of the 39 XY individuals had two ovaries, and another had one ovary and one testicle.

Although most embryos developed normally, this research has opened new avenues into how micronutrients like iron might interfere with the process of sex determination, which has long been considered "rigid" and determined by genes.

Currently, there is no scientific evidence to confirm a similar phenomenon occurring in humans. However, researchers are increasingly interested in the possibility that maternal nutrition, as well as the impact of toxic environmental factors, may affect gene activity during the early development of the fetal gonads, a process that is extremely sensitive and susceptible to influence.

This new finding also raises broader questions: Does iron play a crucial role in regulating genes other than SRY? Does it influence neurodevelopment and other biological systems in the fetus? These questions are opening up a promising avenue of research in the fields of developmental biology and modern fetal medicine.

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MINH HAI

Source: https://tuoitre.vn/me-thieu-sat-khi-mang-thai-co-the-khien-gioi-tinh-con-bi-thay-doi-20250609121705382.htm