Male fetuses: late miscarriages more common

Male fetuses: late miscarriages more common

Late miscarriages are more common in male fetuses
01.12.2014

In a new British study, scientists found that late miscarriages are more common in male fetuses. According to the researchers, the risk is about ten percent higher. The reasons for this are not clearly understood.

Late miscarriages are particularly difficult for parents. Miscarriages are generally a dramatic burden for the parents concerned. The later it comes, the more they suffer. As the “Hamburger Abendblatt” reports, quite a few of the miscarriages do not take place until after the fifth month of pregnancy. At a time, then, when the parents mostly think they are safe. In 2009 it hit 2.6 million unborn children worldwide. This is comparable to the number of babies who die of sudden infant death after birth. The late miscarriages have so far been a mystery to scientists. Early premature births are reportedly often triggered because of fetal malformations or chromosomal abnormalities. In the case of late miscarriages, however, little is known about why they occur and why so late.

30 million pregnancies examined To better understand the phenomenon, a research team led by Fiona Mathews from the University of Exeter in the UK has examined more than 30 million pregnancies and their outcomes. The scientists report in the specialist magazine "BMC Medicine" that late miscarriages are more common in boys than in girls. According to this, the risk is around ten percent higher. This corresponds to around 100,000 male stillbirths per year worldwide. In the respective countries, there were different definitions of late miscarriage in the data, for example a birth weight of at least 400 or 500 grams or the 20th to 28th week of pregnancy.

Proportion of stillbirths lower in richer countries As the researchers emphasized, the difference between the sexes was the same for the different time slots. According to this, 6.23 out of every 1,000 births were stillborn among boys and 5.74 among girls. The proportion of stillbirths was generally significantly lower in the richer nations than in the poorer ones. For example, only two out of 1,000 children in Finland were stillborn if their pregnancy was advanced, whereas in Nigeria and Pakistan more than 40 were born. However, the percentage difference between girls and boys remained. Only China and India were exceptions, where female fetuses are often aborted.

Causes not clearly clarified As the researchers report, the miscarriage rate has hardly decreased in the past 15 years. In the industrialized countries, the cause remains unclear for around a quarter of miscarriages. Differences in placenta function and a more sensitive reaction of male fetuses to factors such as obesity (obesity), smoking or an older mother are some suspected causes. Earlier studies also found that taking anti-inflammatory drugs during pregnancy may also increase the risk of miscarriage. The so-called non-steroidal anti-inflammatory drugs (NSAID) were mentioned, which also contribute to lowering fever and inhibiting blood clotting. It has long been known that pregnancies with boys are apparently more complicated. Not only is the rate of miscarriages generally higher, but also that of premature births. (ad)

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