Background

• This important public health question was identified by the U.S. Departments of Agriculture (USDA) and Health and Human Services (HHS) to be examined by the 2020 Dietary Guidelines Advisory Committee.
• The 2020 Dietary Guidelines Advisory Committee, Dietary Fats and Seafood Subcommittee conducted a systematic review to answer this question with support from the Nutrition Evidence Systematic Review (NESR) team.
• The goal of this systematic review was to examine the following question: What is the relationship between seafood consumption during pregnancy and lactation and neurocognitive development in the child?

Conclusion statements and grades:

Seafood intake during pregnancy

Developmental domains:

• Moderate evidence indicates that seafood intake during pregnancy is associated favorably with measures of cognitive development in young children. (Grade: Moderate)
• Limited evidence suggests that seafood intake during pregnancy may be associated favorably with measures of language and communication development in the child. (Grade: Limited)
• Insufficient evidence is available to determine the relationship between seafood intake during pregnancy and movement and physical development in the child. (Grade: Grade not assignable)
• Insufficient evidence is available to determine the relationship between seafood intake during pregnancy and social-emotional and behavioral development in the child. (Grade: Grade not assignable)

Attention deficit disorder or attention-deficit/hyperactivity disorder-like traits or behaviors:

• Insufficient evidence is available to determine the relationship between seafood consumption during pregnancy and attention deficit disorder or attention-deficit/hyperactivity disorder-like traits or behaviors in the child. (Grade: Grade not assignable)

Attention deficit disorder or attention-deficit/hyperactivity disorder diagnosis:

• No evidence is available to determine the relationship between seafood consumption during pregnancy and diagnosis of attention deficit disorder or attention-deficit/hyperactivity disorder in the child. (Grade: Grade not assignable)

Autism spectrum disorder:

• Insufficient evidence is available to determine the relationship between seafood consumption during pregnancy and autism spectrum disorder-like traits or behaviors or autism spectrum disorder diagnosis in the child. (Grade: Grade not assignable)

Academic performance:

• No evidence is available to determine the relationship between seafood intake during pregnancy and academic performance in the child. (Grade: Grade not assignable)

Anxiety:

• No evidence is available to determine the relationship between seafood intake during pregnancy and anxiety in the child. (Grade: Grade not assignable)

Depression:

• No evidence is available to determine the relationship between seafood intake during pregnancy and depression in the child. (Grade: Grade not assignable)

Seafood intake during lactation

• No evidence is available to determine the relationship between maternal seafood intake during lactation and neurocognitive development in the child. (Grade: Grade not assignable)

Methods

• A literature search was conducted using 4 databases (PubMed, Cochrane, Embase and CINAHL) to identify articles that evaluated the intervention or exposure of seafood consumption during pregnancy and lactation and the outcomes of neurocognitive development. A manual search was conducted to identify articles that may not have been included in the electronic databases searched. Articles were screened by two NESR analysts independently for inclusion based on pre-determined criteria.
• Data extraction and risk of bias assessment were conducted for each included study, and both were checked for accuracy. The Committee qualitatively synthesized the body of evidence to inform development of conclusion statements, and graded the strength of evidence using pre-established criteria for risk of bias, consistency, directness, precision, and generalizability.

Summary of the evidence:

Seafood intake during pregnancy

• This review included 26 articles from 18 prospective cohort studies (PCSs) published between January 2000 and October 2019.
• The 2020 Dietary Guidelines Advisory Committee used the following seafood definition: marine animals that live in the sea and in freshwater lakes and rivers. Seafood includes fish (e.g., salmon, tuna, trout, and tilapia) and shellfish (e.g., shrimp, crab, and oysters).
• Developmental domains:

  • Evidence from 21 articles from 15 PCSs indicated predominantly beneficial associations between seafood intake during pregnancy and measures of cognitive development, including milestone achievement and intelligence, particularly in young children.
  • Evidence from 15 articles from 12 PCSs suggested beneficial associations between seafood intake during pregnancy and measures of language and communication development. However, results were less consistent than for cognitive development. Furthermore, 8 articles assessed measures of verbal intelligence or verbal intelligence quotient (IQ), which may be less specific assessments of language and communication development.
  • Few detrimental associations between seafood intake during pregnancy and measures of child cognitive or language development were found.
  • Heterogeneity in exposure and assessment methods, and ages of children at follow-up, made it difficult to determine a relationship between seafood intake during pregnancy and movement and physical development or social-emotional and behavioral development.
• Four articles, from 3 PCSs, found inconsistent results when examining the relationship between seafood intake during pregnancy and attention deficit disorder (ADD)-like or attention-deficit/hyperactivity disorder (ADHD)-like traits or behaviors in the child, with studies reporting either null or protective associations.
• Three PCSs assessed autism spectrum disorder (ASD)-like traits or behaviors or ASD diagnosis but heterogeneity in outcome assessment methods and child age across the 3 PCSs made it difficult to determine a relationship between seafood intake during pregnancy and ASD-like traits or behaviors or ASD diagnosis.
• No studies that met inclusion criteria assessed the relationship between seafood intake during pregnancy and academic performance, anxiety or depression in the child.
• Thirteen articles accounted for maternal mercury exposure and most found that controlling for mercury exposure strengthened or had little impact on the association between seafood intake during pregnancy and developmental outcomes.
• There were limitations in the evidence:

  • Heterogeneity in seafood intake categories used to compare seafood intake levels across studies made it difficult to assess precision and compare magnitude of associations.
  • Key confounders were not consistently accounted for and there was heterogeneity in exposures, outcomes, and child age.

Seafood intake during lactation

• No studies that met inclusion criteria assessed the relationship between maternal seafood intake during lactation and neurocognitive development in the child.