Women born to obese mothers are more likely to start puberty earlier than daughters of mothers who are normal or underweight, according to new research.
The study, published today in the American Journal of Epidemiology, involved more than 15,000 girls ages 6 to 11 in northern California, using the child development medical records for analysis.
The normal age for girls to begin puberty is between 8 and 13 years, and early puberty is defined as the beginning when a girl is under 8 years old.
Research, adjusting factors such as age, ethnicity, and mother's level of education when she gives birth and if she smokes, found that early puberty was 39 percent more likely among girls born to obese mothers , and 21 percent more likely among people with overweight mothers.
The gap was even greater when girls were compared to mothers who were overweight and underweight. The daughters of overweight mothers started puberty on average seven months earlier than those of mothers with low birth weight.
It is already known that the weight of a mother can affect the weight of her children.
But this is the first large-scale study that shows that it can also affect the age at which a daughter reaches puberty. The researchers believe that the association could be related to fetal development in the uterus.
"What we are learning is that the intrauterine environment can affect the time of future pubertal development," Ai Kubo, a researcher at Kaiser Permanente in Northern California and one of the authors of this study, said in a news release. . "[This] makes sense since human brains develop in the uterus and the brain releases hormones that affect puberty."
Early puberty may be associated with a number of health problems
It is known that girls who experience early puberty experience higher rates of depression and anxiety. Later in life, they are more likely to be diagnosed with diabetes, heart problems, and some breast and reproductive cancers.
However, this study did not follow girls with early puberty for years or at the rates at which they suffered such health problems. The researchers also looked at only the age at which the girls started puberty, not the time it took to complete it.
When comparing groups of girls by ethnicity, the study found that the association between a mother's weight and the age of a daughter at the onset of puberty was strongest for children of Asian ethnicity. Girls born to overweight Asian mothers were 53 percent more likely to start puberty earlier than daughters of normal-weight Asian mothers.
American girls in general have begun in recent years to begin puberty at younger ages, in part because of the higher rates of childhood obesity.
However, the average age of puberty has also declined for children who are not overweight, which leads doctors to think that other factors besides a girl's weight may be involved.
Although this study was adjusted for several factors, including the weight of the child before puberty and the age of the mother, and if he smoked, it is not certain that all possible factors that could affect the onset have been taken into account. of puberty.
The research also found that girls of mothers with hyperglycaemia, a high blood sugar level, were more likely to start puberty early.
Interestingly, no such association was found when mothers had gestational diabetes, a condition in which blood sugar levels temporarily increase during pregnancy. The researchers believe that this could be because women with this diagnosis took extra care of their health.
"It is possible that women diagnosed with gestational diabetes were more careful with weight and diet, which could have changed the amount of weight gain," Kubo suggested.
George Gillett is a medical resident affiliated with the University of Oxford who works at the ABC News Medical Unit.