Girls who have a low weight at birth may be less active and have a higher risk of obesity in adulthood, according to a study published in the International Journal of Obesity.
Researchers from Baylor College of Medicine (BCM), the USDA/ARS Children’s Nutrition Research Center (CNRC) and Texas Children’s Hospital, conducted a report on the offspring of obese female mice.
Previous research has shown that genetically normal female offspring of obese female mice were prone to obesity and inactivity.
But Dr. Robert Waterland, associate professor of pediatrics and nutrition at BCM, realized that the low birthweight of the offspring signified the mice were growth-restricted in the uterus.
Dr. Waterland says:
“This was surprising because babies born to obese human women tend to be larger at birth, although there is a slightly elevated risk of low birth weight as well.”
The findings encouraged the researchers to analyze historical reports of people who had been born in famine conditions, including women born during the Dutch Hunger Winter near the end of World War II, the great famine in China (1959-1961) and the Biafran famine during the Nigerian civil war (1967-1970).
The results showed that women whose growth had been restricted in the womb had a higher risk of obesity later in life. But this was not the case for men.
However, the study of the female mice shows that the mice did not become obese because they were overeating, but because they were less active. Again, this was not apparent in male mice.
But Dr. Waterland says these results could make sense from an evolutionary point of view. He points to times of food scarcity and adds that it could be more important for females to be developmentally “programmed” to conserve energy for childbearing.
The researchers note that although it is important to encourage small babies at birth to achieve a normal weight for their age, these results show that it may not be beneficial long-term.
Dr. Waterland says, however, the research may indicate that children should be active from an early age:
“Given that human studies also show female-specific obesity following early growth restriction, it may be prudent to encourage parents of a low birth weight child to promote healthy physical activity – particularly if that child is a girl.
Millions of low birth weight babies are born every year, so this could be an important factor in the worldwide obesity epidemic.”
Other research has shown that babies who are small for their gestational ages are more likely to develop other ailments, such as respiratory tract problems, anaemia and various gastrointestinal problems.