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Pregnancy and Birth to 24 Months Systematic Review

Pregnancy and Birth to 24 Months Project Nutrition Evidence Systematic Review Methodology


The purpose of the P/B-24 Project, completed in 2018, was to conduct a series of systematic reviews on diet and health for women who are pregnant and for infants and toddlers from birth to 24 months of age. This project was an initiative led jointly by USDA and HHS. A broadly representative group of Federal researchers and program leaders, called a Federal Expert Group (FEG), also provided input throughout the P/B-24 Project. 

USDA’s Nutrition Evidence Systematic Review (NESR) team conducted systematic reviews for the Pregnancy and Birth to 24 Months (P/B-24) Project. To conduct the P/B-24 systematic reviews, NESR’s staff worked with four Technical Expert Collaboratives (TECs), which are groups of 7–8 leading subject matter experts. 

It is important to note that the purpose of P/B-24 Project was to review the evidence on a select number of questions, not to establish or recommendation dietary guidance.

A detailed description of the systematic review methodology used for the P/B-24 Project has been published and is available: 

Obbagy JE, Spahn JM, Wong YP, Psota TL, Spill MK, Dreibelbis C, Güngör D, Nadaud P, Raghavan R, Callahan EH, English LK, Kingshipp BL, LaPergola CC, Shapiro MJ, Stoody EE. Systematic review methodology used in the Pregnancy and Birth to 24 Months Project. Am J Clin Nutr. 2019;109(7):698S–704S. doi: 10.1093/ajcn/nqy226. 

This peer-reviewed publication includes a description of the roles of those involved in conducting the systematic reviews, including NESR analysts, NESR librarians, and TEC members, as well as processes for assessing and managing conflict of interest. The publication provides information about NESR’s processes for developing and prioritizing systematic review questions, searching for and selecting studies, extracting and assessing the risk of bias of data from each included study, synthesizing the evidence, developing a conclusion statement, grading the evidence underlying the conclusion statement, and recommending future research. 

Two of the tools used by NESR in the process of conducting a systematic review are described in the publication, and are available at the links below:

  • Nutrition Evidence Library (NEL) Bias Assessment Tool
  • NESR Grading Rubric

Aspects of the methodology described in the publication was tailored for each of the systematic reviews conducted as part of the P/B-24 Project. Details regarding those tailored methods, including the literature selection criteria (inclusion/ exclusion criteria), literature search strategies, are available in each of the full systematic reviews. 

Each TEC worked independently of one another, and their work concluded with the completion of the systematic reviews and their respective peer-reviewed publications. As noted previously, the purpose of P/B-24 Project was to review the evidence on a select number of questions, not to establish or recommendation dietary guidance. 

The full systematic reviews completed by each TEC can be found here:


Infant milk-feeding practices

Complementary feeding

Flavor exposure and feeding practices