Children’s cognitive skills now linked to mother’s weight

By Wachira Kigotho

In most traditional cultures, having a fat belly was a symbol of wealth and good life. According to Ben Okri, the Nigerian award-winning novelist and political commentator, even today, nothing pleases a politician more than rubbing his fat tummy while standing in front of thin and starving villagers.

Nonetheless, in a continent where many people survive on food aid, body size does matter in Africa and cuts across the gender divide. Notably in some African communities, brides-to-be are encouraged to eat more food and become plump.

“An African woman is deemed to be beautiful when fat and not thin,” says Okri.

However, medical researchers are worried that women who are obese before they become pregnant are at higher risk of having children with lower cognitive ability, as measured by mathematics and reading scores of children aged between five and seven years.

According to Dr Pamela Salsberry, a professor of nursing at Ohio State University pre-pregnancy obesity was associated to low learning ability among children.

The study that appeared in the current issue of Maternal and Child Health Journal is the first research to link pre-pregnancy obesity of mothers to low academic achievement of their children.

Risk factors

“The new piece here is we have a measure associated with the foetus’ environment to add to that set of potential risk factors,” says Salsberry.

The researchers calculated the mothers’ body mass index based on their heights and weights. Thereafter, their children’s cognitive ability in reading recognition and mathematics assessments was gauged based on their performance on Peabody Individual Achievement Test, a popular academic measurement procedure.

Even after controlling for all other variables, the analysis showed maternal pre-pregnancy obesity was negatively associated with mathematics and reading test scores.

“On average, children of obese women scored poorly on reading and maths than did children of healthy-weight women,” says Rika Tanda, lead author of the study.

The study seems to support findings in earlier studies that showed various conditions affect childhood learning processes. In the past, educational researchers had indicated how home environment, family income and a mother’s education could impact on a child’s cognitive skills. But for the first time now, it is clear a mother’s obesity status could impact on her children’s early learning capacity.

According to Tanda, the effects of pre-pregnancy obesity to a child’s cognitive ability were scaled to be equivalent to a seven-year decrease in the mother’s education and significantly lower household income.

“Those are two well-known risk factors that negatively affect childhood cognitive function,” said Tanda.

But taking into account of the large population study, researchers say they have no evidence that one woman’s decision to change her weight immediately before pregnancy will alter her child’s cognitive outcome.

“Still our findings suggest that children born to women who are obese before pregnancy might need extra support,” he said.

Nevertheless, it is not just for their children’s sake that young women are being encouraged to shed extra weight.

“It is vital for the health of the mother, although maternal obesity cannot always be equated to being unhealthy.”

But, socio-economic data from the study supported previous findings that several post-birth conditions can have a positive association with higher children’s test scores. For instance, a stimulating home environment with plenty of books, a safe play environment, frequent family meals, higher family income and higher maternal education levels often erased pre-pregnancy obesity effects on childhood cognitive ability.

Foetal brain

Subsequently, researchers concluded young women who grow up poor, who have less access to healthy foods resulting in diets that are of poorer quality are on average at higher risk of having children with learning disadvantages.

Unfortunately, according to Dr Patricia Reagan who was also a member of the study team, the scientists were unable to explain for sure how pre-pregnancy obesity might affect foetal brain.

The new study joins a number of previous studies that have suggested that a mother’s impaired metabolic processes affect the foetal brain cell growth and formation of synapses.

Mother’s characteristics

The recent study seems to suggest that all children are not born equal and besides heredity, a child’s road to academic success begins in the mother’s womb. In this case, the emerging evidence is that fat mothers are likely to give birth to less intelligent children compared to their slimmer counterparts.

According to FAO, sub-Saharan Africa may be where most of the hungry live, but obesity epidemic has taken root, especially among urban women.

Since the condition is associated with limited academic outcomes, then there is need to start taking concrete measures to reduce the burden of obesity.