2. Experimental Section
2.1. Eligibility Criteria
2.2. Search Strategy
|Search terms||Keywords searched||BOOLEAN operator|
|Term 1||Pregnant or pregnancy||Pregnan*||AND|
|Term 2||Fish or seafood||Fish|
|Term 3||Neurodevelopment or neurodevelopmental or cognition or cognitive||Neurodevelopment*|
|Reference||Daniels et al., 2004 ||Oken et al., 2005 ||Hibbeln et al., 2007 ||Gale et al., 2008 |
|Type of study||Observational cohort (Avon Longitudinal Study of Parents and Children-ALSPAC)||Prospective cohort|
|Observational cohort (ALSPAC)||Observational cohort|
|NHMRC Level of evidence ||Level III-3||Level III-3||Level III-3||Level III-3|
|Population||Pregnant women living in Bristol & surrounds, United Kingdom (UK).||Pregnant women recruited in Massachusetts, United States of America (USA)||Pregnant women in Bristol & surrounds, UK.||Pregnant women recruited in Southampton, UK.|
|N—sample size||7421 mother-child pairs.||135 mother-child pairs||5449 children assessed.||217 mother-child pairs.|
|Method||Measured fish intake during at 32 weeks gestation by Food Frequency Questionnaire (FFQ) during. Breastfeeding, child fish consumption, maternal dental & lifestyle questionnaires.|
Neurodevelopmental testing of child completed by mother using ALSPAC adaption of the MacArthur Communicative Development Inventory (MCDI) at 15 months and Denver Developmental Screening Test (DDST) at 18 months of age.
|Fish and seafood intake measured via a validated FFQ (calibrated for LCn-3PUFAs in blood) at 28 weeks gestation.|
Infant cognition measured using
Visual Recognition Memory (VRM) paradigm at 6 months of age.
|Seafood consumption assessed at 32 weeks gestation via FFQ.|
Postal questionnaires on diet, education, social, behavioural and developmental outcomes at child age: 6, 18, 30, 42, and 81 months.
Wechsler Intelligence Scale for Children III used to assess Intelligence Quotient (IQ) at 8 years and Strengths and Difficulties Questionnaire (SDQ) conducted. Presented as percentage of children in the lowest quartile for WISC-III and ALSPAC development test subscales or in the suboptimum range of behavioural scores for the SDQ. Tested at 42 months, 7 and 8 years.
|Two FFQs during pregnancy (at 15 weeks and 32 weeks) were used to estimate fish intake in early and late pregnancy.|
Cognitive & behavioural outcomes in offspring at 9 years using the Wechsler Abbreviated Scale of Intelligence. The SDQ was used to measure maladaptive behaviour.
|Intervention/comparator||Fish intake: rarely/never, once a fortnight, 1–3 times per week, 4 or more times per week.|
Assumed each fish serve was 4.5 ounces (~0 g, 64 g, 255 g and 510 g per week).
|Second trimester fish servings: more than 2 weekly fish servings compared to 2 or less.|
Did not convert servings to grams.
|Comparing no seafood intake and 1–340 g per week with more than 340 g per week (3 servings is estimated as 340 g).||Fish servings per week in early and late pregnancy: never, less than 1, 1–2 times, 3 or more times.|
Oily fish servings in both early and late pregnancy: never, less than 1, 1 or more.
Amount not specified in grams
|Outcome||Fish consumption during pregnancy resulted in modest but significant improvement in developmental scores for language & social activity at 15–18 months age.|
Odds ratio (OR) and 95% confidence interval (CI) for high test score for MCDI:
Vocabulary comprehension = 1.5 (1.1–2.0) for one or more serves compared to no serves.
Social activity = 1.6 (1.2–2.2) for 1/fortnight, 1.7 (1.3–2.2) for 1–3/week and 1.8 (1.4–2.4) for 4+ serves/week compared to no serves.
|Non-significant increase in VRM of 2.8 points for each additional weekly fish serving (95% CI = 0.2 to 5.4). When mercury confounder was adjusted for, this association became significant: 4.0 (1.3 to 6.7).|
Mothers consuming greater than 2 fish serves per week had infants with the greatest VRM scores.
|Seafood intake during pregnancy was associated with a significant reduction in percentage of children with suboptimal IQ and behaviour test scores in 9 of 23 outcomes.|
Non-seafood consumers during pregnancy had children who scored lower on tests of verbal IQ at 8 years: OR (CI) for no seafood = 1.48 (1.16–1.90); some seafood 1.09 (0.92–1.20) compared with >340 g per week [overall trend: p = 0.004].
|Oily fish consumption more than once per week versus no oily fish reduced the risk of hyperactivity.|
No association with fish consumption in early pregnancy and full scale IQ, however, total fish intake in late pregnancy of 1 to 2 serves per week was associated with having a child with higher IQ at age 9 years.
Higher intakes (3 or more serves per week) did not show a statistically significant improvement.
Regression coefficients (95% CI) for fish consumption and full scale IQ: less than once per week vs. no fish = 7.76 (0.38 to 15.1), once or twice per week vs. no fish = 6.91 (0.19 to 13.6).
Verbal IQ & fish consumption: Increase of 7.32 (0.26 to 14.4) with fish consumption once or twice per week. 8.07 (0.28 to 15.9) with three or more serves per week.
|Type of study||Prospective population-based cohort||Prospective cohort (Project Viva)||Prospective birth cohort||Birth cohort study|
|NHMRC Level of evidence ||Level III-3||Level III-3||Level III-3||Level III-3|
|Population||Pregnant women recruited throughout Denmark.||Pregnant women recruited in Massachusetts, USA.||Pregnant women living in Menorca, Spain.||Pregnant women recruited in Japan.|
|N—sample size||25,446 mothers-child pairs.||341 mother-child pairs.||392 mother-child pairs||498 mother-infant pairs|
|Method||Validated FFQ conducted at 25 weeks gestation to estimate fish intake.|
Standardised interview with mother used to assess child neurodevelopment at 6 and 18 months. Measured the odds of improved development scores due to fish intake. No individual comparison for each category—pooled estimate only.
|Fish intake during pregnancy estimated via semi-quantitative FFQ.|
Peabody Picture Vocabulary Test (PPVT) and Wide Range Assessment of Visual Motor Abilities (WRAVMA) tested at ~38 months age of child and analysed for association with fish intake.
|FFQ of typical diet during pregnancy completed 3 months after delivery and fish and shellfish/squid intake estimated.|
Neurodevelopment (as well as diet and physical activity) assessed when child was 4 years of age using the McCarthy Scales of Children’s Abilities (MCSA) tests—global cognitive scale & 5 subscales (perceptive-performance, memory, verbal, quantitative and motor).
|Fish intake measured via FFQ 4 days after birth of child. Trained examiners conducted Neurodevelopmental testing of child was completed via a Neonatal Behavioural Assessment 3 days post birth (28 behavioural & 18 reflex items).|
|Comparator and Comparison||Fish intake in quintiles|
Categories: no fish (0 g), 1–2 servings (1–340 g per week), or 3 or more servings per week (over 340 g).
No fish serves, less than or equal to 2 servings per week, greater than 2 servings per week.
|Maternal fish intake of more than 2–3 times per week compared to up to once per week.|
No mention of intake in grams.
|Maternal seafood intake in grams (average intake = 300–360 g per week).|
|Outcome||Highest 3 quintiles of fish intake resulted in improved motor, social/cognitive and total development scores at 18 months:|
OR (95%CI) = 1.28 (1.20, 1.38) for highest versus lowest quintile.
This association was less obvious at 6 months (only the highest quintile showed significant improvement).
|Offspring of women who ate fish more than twice a week scored significantly higher on WRAVMA drawing and total scores compared with no serves.|
OR (95%CI) for WRAVMA drawing = 6.0 (1.8, 10.2) for more than two serves per week compared with no serves.
WRAVMA total score = 5.3 (0.9, 9.6) for more than two serves per week compared to no serves.
|Pregnant women fish consumption greater than 2–3 times per week had children with significantly higher cognition and motor development scores compared to women consuming fish less than once a week. This association was only significant in children breastfed for up to 6 months.|
Greater than 3 serves per week was not associated with improved outcomes.
|Seafood intake weakly (p = 0.1) correlated with motor development. Other measures of neurodevelopment not significant in either direction.|
|Evidence Base||Satisfactory||NHMRC Level III (cohort studies) with moderate risk of bias .|
|Consistency||Good||Seven out of eight studies demonstrated a positive association between fish intake and foetal neurodevelopment.|
|Clinical impact||Satisfactory||Trend towards improved neurodevelopment with significant results in several domains.|
|Generalisability||Good||All studies in pregnant women.|
|Applicability||Poor||A variety of populations studied from different countries where type of fish and the level of contaminants would likely vary.|
Conflicts of Interest
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