[Influence of hemoglobin level during early gestation on the development of cognition of pre-school children].

Objective: The purpose of this study was to evaluate the effect of hemoglobin (Hb) level during early gestation on the cognitive development of children at 4 - 6 years of age.

Methods: A total number of 3609 children were randomly selected from all the live birth infants whose mothers participated in a community intervention trial during 1993 - 1996 in 13 counties or cities in Jiangsu and Zhejiang provinces. Hb concentration during early gestation was measured at first prenatal examination and intelligence quotients (IQ), including full-scale, verbal and performance were assessed using Chinese-Wechsler Intelligence Scale for Children in 2000 - 2001 when these children had a mean age of 68 months.

Results: Compared with children whose mothers were non-anemic during early gestation, children whose mothers were anemic had a 0.6 point higher mean verbal scale IQ, a 0.9 point higher mean performance IQ and a 0.8 point higher mean full-scale IQ. These differences were not statistically significant when children's gender, age at intelligence test, region, parity and mother's IQ, education level and occupation were adjusted for. When mother-child pairs were divided into 5 sub-groups of every 20 percentiles according to Hb concentration during early gestation, verbal IQ scores of the lowest (Hb < 103 g/L), the moderate (110 g/L ≤ Hb < 116 g/L) and the highest Hb concentration group (Hb ≥ 124 g/L) were 91.6 ± 18.9, 92.8 ± 18.2 and 90.3 ± 18.6, respectively. The performance IQ scores were 104.7 ± 15.2, 104.5 ± 14.3 and 103.5 ± 15.1, and full-scale IQ scores were 97.8 ± 17.3, 98.4 ± 16.3 and 96.4 ± 17.4, respectively. After controlling for confounding factors, children whose mothers had highest Hb concentration were 54% (OR = 1.54, 95%CI: 1.13 - 2.11) more likely to have poor verbal scores and 53% (OR = 1.53, 95%CI: 1.10 - 2.12) more likely to have poor full-scale scores than children whose mothers had moderate Hb concentration. No statistical associations were noticed between high Hb concentration and performance scores, or between low Hb concentration during early gestation and verbal, performance as well as full-scale score of pre-school children.

Conclusion: High maternal Hb concentration during early gestation might adversely affect children's cognitive development.