Po drugie, wg tego artykułu:
- wnioski o rosnących trudnościach z zajściem w ciążę po 30 roku życia opierają się na danych z zamierzchłych czasów (tzn. kiedy medycyna i ogólny poziom życia były poniżej krytyki wg obecnych standardów)
- prawdopodobieństwo wystąpienia wad genetycznych u płodu rośnie z wiekiem matki, ale jest mocno przeszacowaneThe widely cited statistic that one in three women ages 35 to 39 will not be pregnant after a year of trying, for instance, is based on an article published in 2004 in the journal Human Reproduction. Rarely mentioned is the source of the data: French birth records from 1670 to 1830. The chance of remaining childless—30 percent—was also calculated based on historical populations.
In other words, millions of women are being told when to get pregnant based on statistics from a time before electricity, antibiotics, or fertility treatment. Most people assume these numbers are based on large, well-conducted studies of modern women, but they are not.
Co do mężczyzn, to natrafiłem na artykuł, w którym opisane są próby powiązania wieku ojca z prawdopodobieństwem powstania mutacji odpowiedzialnych za schizofrenię i zaburzeń spektrum autyzmu u dziecka, aleThe risk of chromosomal abnormalities such as Down syndrome does rise with a woman’s age—such abnormalities are the source of many of those very early, undetected miscarriages. However, the probability of having a child with a chromosomal abnormality remains extremely low. Even at early fetal testing (known as chorionic villus sampling), 99 percent of fetuses are chromosomally normal among 35-year-old pregnant women, and 97 percent among 40-year-olds. At 45, when most women can no longer get pregnant, 87 percent of fetuses are still normal. (Many of those that are not will later be miscarried.) In the near future, fetal genetic testing will be done with a simple blood test, making it even easier than it is today for women to get early information about possible genetic issues.
To jednak bardziej tytułem dygresji.Not all such mutations are deleterious, and even the ones that are must occur in the right combinations to generate disease. “The observed effect is a significant one but not one necessarily to cause great worry among prospective older fathers,” Darren Griffin, a professor of genetics at University of Kent, wrote in a comment on the results. “There are three billion of letters in the DNA code of humans and the numbers of mutations detected in this study are in the dozens…and not realistically likely to deter more mature fathers from having children.”