The age of a woman can decide whether to have only a son.
Marko PEKIC/Getty Image
You may assume that the opportunity to have a son or daughter is 50/50, which is similar to a coin throwing, but some women seem to have only one sex.
“In my personal experience, I saw a family (and) family with only a woman or a boy in a family. Shiwen King At Harvard University. “Is this purely an opportunity, or is there a fundamental biology that can explain this phenomenon?”
The proportion of boys vs. girls at birth is approximately 50:50 at the population level. It is mainly determined by the child’s sex because it is likely to contain X or Y chromosomes.
But the king and colleagues wondered if women could play a role. For more information, we analyzed the data collected from more than 58,000 mothers in the United States, who have registered two separate studies on contraception and maternity health. 61 %of these women had two children, 30 %were three children, and 8 %had four children, and the remaining women had more than five.
The researchers compared the gender of female children with eight maternal characteristics: height, body mass, race, hair color, blood type, chronology (the most attention time), the age of the first child between the first menstrual age and the first child between 13 and 48 years old.
The team found that when the first mother was 28 years old, when she first became a mother, she had a 43 % chance of having a child of sexual intercourse compared to the 34 % probability of people under 23 years of age.
Wang said, “We found that the older maternity age was related to only girls and boys at first birth. Nothing of other characteristics was not related to sexual intercourse.
WANG says it’s not clear why maternal age will affect, but it can go down to biological changes in different women. For example, the previous study is shorter with the first stage of the menstrual cycle. I prefer the birth of a boyReduction of vaginal pH according to age You can support the survival of sperm containing X chromosomesThe king says.
However, the result can be explained by the action factors. Joshua Wild At Oxford University. He said that older women are likely to plan their family size. This can be determined to stop after two boys of different men and women, but young women are more likely to have children of other sexual intercourse who are less interested in family size.
Wilde says further research is needed to analyze the syntax of how behavior, environment and biological factors affect the baby’s gender, Wilde says.
subject :
