Association of periconceptional folic acid supplementation with the intelligence quotient of offspring at 6-year-old and modification effects of nuts consumption during pregnancy and breastfeeding: a birth cohort study in Shanghai

Abstract

ObjectiveTo evaluate long-term impact of periconceptional folic acid supplementation on the intelligence quotient (IQ) of offspring, as well as potential modification effects of nuts consumption during pregnancy and breastfeeding duration on the association of maternal folic acid supplementation with offspring′s IQ.MethodsThe information on maternal folic acid supplementation and frequency of nuts consumption was collected through a structured questionnaire interview conducted at 12 – 16 gestational weeks among pregnant women being enrolled in the Shanghai-Minhang Birth Cohort Study (S-MBCS) during April – December, 2012. Information on duration of exclusive breastfeeding of the mothers was collected during postnatal follow-up visits. The mothers′ children were followed up and the children′s intellectual development at the age of 6 years was evaluated with Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV)-simplified Chinese Version at follow-ups by well-trained interviewers. Eventually, 530 mother-child pairs with complete information were included in this study. Multiple linear regression model was used to analyze the correlation between periconceptional folic acid supplementation and the children′s IQ at age of 6 years and to explore potential modification effects of frequency of maternal nuts consumption during pregnancy or duration of exclusive breastfeeding on the correlation. ResultsMultiple analysis showed that the children with maternal folic acid supplements regularly during periconceptional period had better IQ performance, with significantly increased scores of perceptual reasoning index (PRI) of 4.57 (95% confidence interval [95%CI]: 0.13 – 9.02) compared to the children without the maternal supplementation; such effect of maternal folic acid supplementation beginning before the pregnancy was similar to that of supplementation beginning after the pregnancy, with the increased PRI scores of 4.41 (95%CI : – 0.25 – 9.07) and 4.71 (95%CI: 0.11 – 9.31), respectively. In addition, the effect of maternal folic acid supplementation on the children′s PRI was stronger when combined by maternal nuts consumption of ≤ 2 days/week during pregnancy (increased PRI = 5.80, 95%CI: 0.52 – 11.08) or by exclusive breastfeeding of their children less than 6 months (increased PRI = 6.36, 95%CI: 0.89 – 11.83). ConclusionMaternal periconceptional folic acid supplementation is associated with the improvement of offspring’s PRI at 6 years, indicating a protective effect of the supplementation on long-term intelligence development of the children. The beneficial effect was more profound when the supplementation being combined by nuts consumption two days/ per week and less during pregnancy or by exclusive breastfeeding of their children less than 6 months.

Keywords

• folic acid
• periconception
• intelligence quotient of offspring
• modification effect
• cohort study