Data has showed that children born SGA — those with a birth weight below the 10th percentile for babies of the same gestational age — have a higher tendency to develop obesity.
To examine the joint effects of prenatal folic acid, iron and multivitamin supplementation on the risk of obesity in preschoolers born SGA, a total of 8,016 pairs of mother and child from Longhua District in Shenzhen, China, were included in a 2021 study.
The enrolled mothers completed a structured questionnaire about the child’s and parents’ socio-demographic characteristics, pre-pregnancy body mass index (BMI), prenatal supplementation of folic acid, iron and multivitamin, and birth-related variables (mode of delivery, gestational age and birth weight).
The children’s weight and height were measured by trained nurses.
Findings from a series of binary logistic regression models indicated that prenatal supplementation of folic acid was associated with a lower likelihood of obesity in preschoolers born SGA.
In contrast, no significant associations were found between prenatal iron and multivitamin supplementation and childhood obesity.
In addition, crossover analyses revealed that the combination of folic acid and multivitamin supplementation, and the combination of folic acid and iron supplementation, significantly decreased the risk of obesity in girls born SGA.
“When the analyses were stratified by sex, the significant associations were found only in girls and not in boys,” the authors highlighted.
Importance of prenatal nutrients
The prevalence of overweight and obese Chinese preschoolers is approximately 8.4% and 4.2% respectively.
Epidemiological studies have identified associations between SGA and neurodevelopmental delay and childhood obesity, as well as chronic diseases in adulthood such as cardiovascular disease and type 2 diabetes.
At the same time, there is increasing evidence that prenatal nutrients play a crucial role in foetal growth, infant development, and the probability of disease.
Folic acid is known to be pivotal for cellular growth, DNA synthesis, and prevention of major birth defects in the brain and spine, among other functions.
Some studies have also suggested that vitamin B2 could promote the metabolism of folate, while vitamin B6 and vitamin B12 could modulate one-carbon metabolism to affect DNA methylation (a biological process that regulates gene expression and tissue differentiation).
“Our study found that supplementation of both folic acid and iron during pregnancy significantly reduced the risk of obesity among female preschoolers born SGA, but its extent was less than supplementation of folic acid alone.
“Further studies are needed to clarify the mechanisms for prenatal supplementation of iron or multivitamin that modify the effect of folic acid supplementation. More research also needs to be done to decipher the reasons behind sex-specific responses to the prenatal supplementation of nutrients,” said the authors.
It should be noted that the study has several limitations, including the lack of detailed information on the dose, frequency and duration of nutrient supplementation, the specific vitamins in multivitamin supplementation, and the amount of nutrients ingested from diet.
“Nevertheless, our findings support public health programmes that encourage appropriate prenatal maternal folic acid supplementation to reduce obesity levels in girls born SGA,” the authors concluded.
“Joint Effects of Prenatal Folic Acid Supplement with Prenatal Multivitamin and Iron Supplement on Obesity in Preschoolers Born SGA: Sex Specific Difference”
Authors: Qing Lu, et al