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Table 6 Summary of the studies examining associations of maternal iron status with offspring cognitive function

From: Association between maternal nutritional status in pregnancy and offspring cognitive function during childhood and adolescence; a systematic review

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
  1. QS quality score, RB risk of bias, Hb haemoglobin, GA gestational age, MA maternal age, BWT birthweight, SES socio-economic status, ME maternal education, PE paternal education, MIQ maternal intelligence, HE home environment, MS maternal smoking, BF breast-feeding, BMI body mass index
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