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"According to the World Health Organization (WHO), the relationship between the birth of girls and boys depends on the male bad," said the World Health Organization (WHO).
This is a global trend that has been going on for decades.
In Brazil, for example, there were 2.87 million births in 2017 – 1,473,166 men and 1,400,998 women, according to the Brazilian Institute of Geography and Statistics (IBGE)
in the United Kingdom, Since the country began keeping records since 1838, there has been no year when more girls than boys were born
And a proportion of about 105 births per 100 women is considered natural and normal. 19659002] This relationship is generally replicated worldwide, although the difference tends to be even greater in countries such as India or China, where cases of "selective abortions" have been reported among couples who prefer male children.
Although it is very difficult to determine with certainty why more boys are born than girls, some theories try to explain the phenomenon.
Time and Balance
The first deals with the evolutionary element.
Over the years, the proportion between the number of men and women is naturally balanced. And that's why more boys than girls are born.
"Men are at greater risk of dying not only because of the difference between the bades in the average number of deaths due to natural causes, but also by external factors such as accidents, injuries, violence and wars, "says WHO.
"Virtually anytime and anywhere, a man is far more likely to die than a woman," says David Steinsaltz, professor
This means that for an equal number of men and women From women to adulthood, more men will be born, according to the theory.
In fact, in the United Kingdom together, adult women are almost always more numerous than men, in addition to living longer.
In Brazil, the scenario is repeated. The country has 208.4 million inhabitants, including 101.9 million men and 106.5 million women, according to IBGE data based on the population projection (revision 2018).
According to the institute, the life expectancy of male representatives is 72.5 years and that of women 79.6 years.
What happens in the womb
we consider that the chromosome variation Y and X is present in the sperm in the same proportion, so the explanation of why more of boys are born that girls could be in what happens to fetuses in the womb
Some scientists consider that imbalance begins at the time of conception.
A study of the Mbadachusetts Fresh Pond Research Institute, in which scientists from Harvard Universities in the United States and Oxford in England participated, ” clbad=”img img-responsive image-large”/>
. Important sample, comprising more than 140,000 embryos created in fertility clinics, was badyzed and 900,000 test samples, such as amniocentesis (which collects am / pm) amniotic fluid oyster) and 30 million birth and abortion records, natural and induced.
The conclusion?
In an interview with US National Public Radio, Steven Orzack, one of the authors of the study, said the badysis showed that fetal mortality in girls was higher at this time [
The only thing we know, is that between the gestations that end, there are more boys than girls
And scientists say that it is difficult to know exactly what is happening and what are the causes. or X?
Several factors influence the fertilization of the ovum by a Y chromosome, corresponding to the male bad, or X, whose couple determines the female bad.
Among them, there is the age of the parents, the woman's ovulation cycles. ” clbad=”img img-responsive image-large”/>
