Fetuses may develop more slowly in some pregnancies that end in miscarriage, according to a study that used virtual reality to visualize them using vaginal ultrasound scans.
The discovery could be a step toward predicting early in a pregnancy if it is likely to lead to miscarriage, although the technology is not yet ready for clinical use, says Melek Russian Erasmus University Medical Center in Rotterdam, the Netherlands.
More than half of all pregnancies end in miscarriage, although in many cases this happens so early that people do not realize they were pregnant. Some people have more than one miscarriage without knowing why, which means their pregnancy can be a time of great worry.
To learn more about why miscarriages happen, Roussian’s team developed a method of using vaginal ultrasound scans to create highly detailed 3D images of the fetus. The image is magnified until it is about the size of an adult and then inspected by researchers while wearing a virtual reality headset.
The team took these images for 644 pregnant women, 33 of whom miscarried. Transgender people were not included in the study.
Looking at 3D images created around eight weeks after conception, the researchers observed that on average, embryos that miscarried developed more slowly than those from pregnancies that continued to term.
Fetal maturity was assessed through the so-called Carnegie staging system, which indicates which physical features have developed, such as limb buds and early facial features, according to a 23-stage scale.
The team found that a woman’s chances of miscarrying increased by 1.5 percent for each delayed Carnegie stage.
According to the researchers, at eight weeks after conception, this was equivalent to a fetus whose miscarriage was delayed by about four days. “Four days is a huge difference in a very important period of life when all the organs are developing, all the organs are developing,” say team members. Karsten Pieterma,
If the findings are confirmed in larger studies, this could allow doctors to advise people about whether their fetus is developing normally, Roussian says.
It is not known exactly why fetuses that develop more slowly may be more likely to miscarry. Other work has found that aborted embryos or fetuses often have alterations or different numbers of chromosomes, the packages of DNA contained in nearly all of our cells.
She says that some people who have had a previous miscarriage may not want to have a vaginal ultrasound scan, while others may be desperate to check the progress of their pregnancy.
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