Record number of fetal situs inversus in China: scientists don't understand what's going on

China has reported a large-scale and unexplained surge in the number of pregnancies in which the fetus has a rare congenital condition (situs inversus or transposition of internal organs), in which the organs in the chest and abdomen are reversed from their normal positions. In just seven months of 2023, the number of fetuses with this condition quadrupled compared to historical figures.

This is stated in a report published in the New England Journal of Medicine. Scientists are currently unable to determine the cause of this surge but do not rule out some consequences after coronavirus.

The report presents data from two large obstetric centers in the cities of Shanghai and Changsha, which were collected from January 2014 to July 2023.

As it turned out, from 2014 to 2022, the total annual number of such cases was usually about five or six per 10,000 pregnant women undergoing an ultrasound examination. But in 2023, this figure jumped to almost 24 cases per 10,000 examinations.

The biggest spike began in April and lasted until June 2023, before returning to more normal rates.

In total, 56 cases of situs inversus were reported between January and July 2023 among 23,746 pregnant women who underwent an ultrasound examination.

Ultrasounds that diagnosed this condition were usually performed between 20 and 24 weeks of pregnancy. The authors of the report noted that there were no changes in the diagnostic criteria that could explain the "striking increase" in cases.

Scientists do not have definitive evidence, but they speculate that there may be some connection between the surge in situs inversus and the surge in COVID-19 cases that began in late 2022 and lasted until early February.

According to ARStechnica, during this period, all coronavirus restrictions were lifted in China, resulting in a new wave of the disease infecting about 82% of the country's population.

A surge in situs inversus began approximately four months after the peak of COVID-19.

The authors suggest that the virus could have caused this condition directly by infecting the fetus in the womb, or indirectly through the mother's inflammatory reactions.

At the same time, there is no data on whether women who have been diagnosed with a rare fetal condition have ever been infected with COVID-19 during pregnancy.

Scientists also do not rule out that the cause may lie in genetic or environmental factors known to be associated with situs inversus.

The fact that a similar surge was not recorded during other waves of COVID-19 infection also argues against the coronavirus version.

Thus, the authors acknowledge that "no conclusions can be drawn" from this report as to the cause of the unusual spike and call for further research.

It is worth noting that most people with transposition of internal organs do not have any health problems that would be associated with an abnormal anatomical structure.

Earlier, OBOZ.UA reported that researchers managed to create synthetic human embryos for the first time.

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