Table 6 Summary of the studies examining associations of maternal iron status with offspring cognitive function
Author, Year, Sample size, Age, Country, Study design | Nutrient | Cognitive function | Results after adjustment for confounders | QS and RB |
|---|---|---|---|---|
31Wehby GL; 2008  N = 6774  Age 3 years  USA  Population based longitudinal | Prenatal iron supplements (3 months prior to pregnancy and/or during the following 3 months) 36.2 % used supplement | Denver developmental screening-language, personal-social, gross motor and fine motor | Iron use was associated with improved performance in personal-social development (OR = 0.5) but not with language and motor domains Confounders adjusted for: The child’s sex, age, ethnicity, MA, ME, MS, alcohol, drug abuse, income, maternal health status | 11 High |
38Rioux FM; 2011  N = 63  Age 6 Months  Canada  Observational | Hb, serum ferritin at 28-32 weeks gestation 90 % mothers took iron supplements (27 mg of iron) | Brunet-Lezine Scale of Psychomotor Development of Early Childhood. Bayley Scales of Infant Development | No association between maternal gestational Iron status with mental and psychomotor development. Confounders adjusted for: ME, PE, MIQ, income, BF, GA, BWT, birth head circumference, infants’ current weight and Hb | 16 Medium |
39Ferarouei. M; 2010  N = 9983 14 years  N = 10474 16 years  Finland  Prospective Birth cohort study | Hb concentrations at 3rd 7th and 9th gestational months Anaemia | School performance 14 years- Self report 16 years- School report | ↑maternal HB at 9 months-↑ total school performance score (β = 0.03) and theory score at 14 years and total score at 16 years Offspring of mothers with anaemia –low school scores (OR = -0.05 at 14 years and (OR = -0.06) at 16 years Confounders adjusted for: The child’s sex, BWT, pregnancy wanted or not, ME, social class, parity, marital status, MS, maternal mental health status | 18 Low |
40Davidson PW; 2008  N = 229  Age 5, 9, 25and 30 months  Republic of Seychelles  Longitudinal cohort study | Iron- total body stores at 14-24 weeks of gestation assessed before the start of iron supplementation | Bayley Scales of Infant Development: Mental Development Index (MDI) and Psychomotor Development Index (PDI) (9 and 30 months) Infant cognition (Fagan Infantest-novelty preference) and Visual Expectation Paradigm –visual recognition memory (9 and 25 months) A-not-B and Delayed Spatial Alternation: inhibition, working memory, planning and attention (25 months) | No association between maternal iron stores and cognitive function at any age. Confounders adjusted for: The child’s sex, BWT, MA, SES, HE, MIQ and both parents living with the child (yes/no) | 19 Low |
41Lewis SJ; 2013  N = ~3,500  Age 8 years  UK  Population based prospective birth cohort | Hb concentrations Before 18 weeks Hb <11.0 g/dl -8 % After 28 weeks Hb <11.0 g/dl -30 % | Wechsler Intelligence Scale for Children-III- Full- scale IQ | No association between maternal Hb and child’s IQ Confounders adjusted for: GA, ME, the child’s genotype, iron supplementation, population stratification | 15 Medium |
42Tran TD; 2013  N = 378  Age 6 months  Vietnam  Population based prospective cohort study | Iron deficiency anaemia (Hb <11.0 g/dl and serum ferritin <15 ng/ml) during 12-28 weeks of gestation-16 % | Bayley Scales of Infant and Toddler Development-III edition-cognitive score | Infants of anaemic mothers scored 11.6 points (0.77SD) lower in BSID cognitive scores compared to infants of non-anaemic mothers. Confounders adjusted for: parity, MA, ME, wealth index, the child’s birth and current weight, family support, BF. | 18 Low |
43Zhou SJ; 2006  N = 302  Age 4 years; Australia  Double blind randomized controlled trial | Iron supplements (20 mg/day) or placebo from 20 weeks gestation until delivery Compliance-86 % | Stanford Binet Intelligence Scale – IQ (verbal reasoning, visual reasoning, quantitative reasoning and short-term memory) | No difference between the children of supplement group and placebo group in the mean score of composite IQ or any subscales IQ or in the proportion of children whose IQ fell 1 or 2 SD below the mean. Confounders adjusted for: sex, birth order, gestational age, MA, ME, PE, HE, BF | 20 Low |
44Li Q; 2009  N = 1305  Age 3, 6 and 12 months  Double blind cluster randomized controlled trial  China | 3 intervention groups (All received folic acid) Folic acid alone 400 μg (n = 471)-control Iron 60 mg + folic acid 400 μg (n = 438) Multiple micronutrients ((b vitamins (1,2,3 6 AND 12), vitamin A, D, C, E and minerals (zinc, iodine, copper, selenium) + Iron 30 mg + 400 μg folic acid)) (n = 396) Daily supplementation from enrolment until delivery; inadequate information about compliance | Bayley Scales of Infant Development :Mental (MD) and Psychomotor development (PD) | No significant difference in infants MD and PD score at 3 and 6 months and PD score at 12 months between supplement groups Mean MD score among children of multiple micronutrient group increased by 1 to 1.22 points compared to children of folic acid alone, or folic acid + iron group at 12 months Confounders adjusted for: Infants age, sex, gestational age, apgar score, BWT, infant health, maternal age and BMI, parental education, occupation, SES, number of tablets consumed | 19 Low |