A diet rich in refined grains during pregnancy is associated with the development of childhood obesity in the first 7 years of life in children of women who had gestational diabetes mellitus (GDM).
In a recent article published in the American Journal of Clinical Nutrition, Zhu and colleagues set out to determine the association between the consumption of refined grains by pregnant women diagnosed with gestational diabetes mellitus (GDM) and the later development of adverse health outcomes like childhood obesity by the age of 7 years in their offspring.The researchers collected participant information on sociodemographic, perinatal, and medical status using 4 computer-assisted telephone interviews conducted at gestational weeks 12 and 30 and postpartum months 6 and 18. Additionally, a food frequency questionnaire (FFQ) containing 360 items was mailed to each participant at 25 weeks gestational age (GA) to assess maternal dietary intake during the previous month. Parents were sent a follow-up questionnaire about their child’s health and development when the child was 7 years old. In total, the study analyzed the data of 918 mothers with singleton pregnancies from the Danish National Birth Cohort (DNBC) who intended to carry their pregnancies to term and had a permanent address in Denmark. The participants were documented as having GDM during the interviews at 30 week GA or at 6 months postpartum, and any woman having prepregnancy diabetes or recurrent GDM was excluded from the study.
The primary outcome measures of this study were each child’s birth weight and length. Parents were responsible for recording their child’s measurements at 5 and 12 months of age and reporting them during the 18-month postpartum interview. Each child’s weight and height were also recorded on the 7-year follow-up questionnaire. Children were classified as overweight or obese based on age- and sex-specific World Health Organization cut-offs (i.e. ≥ 85 percentile for children aged <5y and ≥ 2 SD for children >5y).For the purpose of this study, refined grains included food such as white bread, bread rolls, rice, pasta, crisp bread, crackers, and cookies. Whole grains were defined as food that included rye bread, rye flour, whole-wheat bread, whole-wheat flour, barley grouts, wheat kernels, wheat bran, and brown rice.
The results showed that of the women included in the study, the average intake of refined grains during pregnancy was 86.2 +/- 49.4 g/d. They also showed that higher intake of refined grain was associated with higher intake of red meat, and was more likely to result in preterm deliveries. Of particular interest, the study demonstrated that maternal intake of refined grain during pregnancy had a positive association with a higher rate of offspring being overweight or obese at age 7.Children born to women with the highest intakes (i.e. ≥4.3 servings/day) were 1.8x more likely to be overweight or obese than children born to women with the lowest intakes (i.e. <1.8 servings/day), and the association was more evident in children who were breastfed for <6 months. The researchers also found that substituting a single serving of refined grains with a serving of whole grains each day was associated with a 10% reduction in offspring being overweight or obese by age 7.
The researchers noted several limitations to this study. Childhood weight and height at age 7, prepregnancy weight and height, and maternal dietary intakes were self-reported, which may have presented inevitable measurement errors. In the case of maternal dietary intakes, which relied on the FFQ, Zhu and colleagues suggested the possibility that participants would have experienced inaccuracies in their recollections of what they ate, a systematic error known as recall bias. This study did not include data on maternal diet in the third trimester after the GDM diagnosis, and the loss to follow-up of study participants may have impacted the results by potentially introducing a selection bias.
In conclusion, it is important for readers to be aware that having a diet that is low in refined grains and high in whole grains is effective in normalizing blood glucose levels, especially in women with GDM. Knowing that a diet rich in refined grain can lead to childhood obesity can help to encourage women to make healthier choices during their pregnancies, especially if they are in high-risk populations such as GDM.
Zhu, Yeyi et al. “Maternal Dietary Intakes Of Refined Grains During Pregnancy And Growth Through The First 7 Y Of Life Among Children Born To Women With Gestational Diabetes”. The American Journal Of Clinical Nutrition, 2017, p. ajcn136291. American Society For Nutrition, doi:10.3945/ajcn.116.136291.
Written By: Kimberly Spencer B.Sc. (Hons)