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Draft Research Plan

Folic Acid Supplementation for the Prevention of Neural Tube Defects


Note: This is a draft Research Plan. This draft is distributed solely for the purpose of receiving public input. It has not been disseminated otherwise by the USPSTF.

The final Research Plan will be used to guide a systematic review of the evidence by researchers at an Evidence-based Practice Center. The resulting Evidence Report will form the basis of the USPSTF Recommendation Statement on this topic.

This draft Research Plan is available for comment from July 10 until August 6, 2014 at 5:00 p.m., ET. You may wish to read the entire Research Plan before you comment.


I. Proposed Analytic Framework

Select Text Description below for details.

 Abbreviations: KQ = key question; NTD = neural tube defect.

[D] Select for Text Description.

II. Proposed Key Questions to Be Systematically Reviewed

1a. To what extent does folic acid supplementation reduce the risk for neural tube defects in women of childbearing age?
1b. Does the effect of folic acid supplementation on neural tube defects vary by demographics (race or ethnicity)?
1c. Do benefits of folic acid supplementation vary by dose, timing, and duration of therapy?
2a. What are the harms associated with folic acid supplementation to the mother, fetus, neonate, or child?
2b. Do the harms of folic acid supplementation vary by dose, timing, and duration of therapy?

III. Proposed Contextual Questions

Contextual questions will not be systematically reviewed and are not shown in the Analytic Framework.

  1. What is the current intake of folic acid from diet and other sources in women of childbearing age?
  2. How does intake of folic acid from diet and other sources vary by pregnancy intention, age, race, ethnicity, and access to foods?
  3. Does folic acid supplementation outside of the periconceptional period reduce neural tube defects?
  4. Does the effect of folic acid supplementation in the periconceptional period on neural tube defects vary by medical risk factors (obesity, poorly controlled diabetes, seizure medications, methotrexate or other folate antagonist therapies, and previous pregnancies with neural tube defects)?
  5. Are there other potential fetal, neonatal, or maternal benefits from folic acid supplementation in the periconceptional period to prevent neural tube defects?

IV. Proposed Research Approach

The Proposed Research Approach identifies the study characteristics and criteria that the Evidence-based Practice Center will use to search for publications and to determine whether identified studies should be included or excluded from the Evidence Report. Criteria are overarching as well specific to each of the key questions.

  Include Exclude
Populations KQs 1a, 1b, 1c: Women of childbearing age (postmenarchal and premenopausal; women with the potential for or planning childbearing)

KQs 2a, 2b: Women of childbearing age (postmenarchal and premenopausal; women with the potential for or planning childbearing); fetus, neonate, or child from index pregnancy; all populations exposed to long-term folic acid supplementation (men, postmenopausal women)

KQs 1a, 1b, 1c: Prepubertal girls; men; women without the potential for childbearing (e.g., postmenopausal, genetic uterine or ovarian abnormalities); no exclusions for harms
Interventions Folic acid supplementation with or without food fortification or naturally occurring folate for neural tube defects and other birth defects

Supplementation with micronutrients (e.g., multivitamin, iron) in combination with folic acid for neural tube defects only

  • Food fortification only
  • Naturally occurring folate only
  • Counseling to improve dietary supplementation
  • Supplementation with micronutrients (e.g., multivitamin, iron) in combination with folic acid for birth defects only
Comparisons KQs 1a, 1b, 2a: Placebo or no treatment; dietary supplementation only; supplementation with prenatal vitamins without folic acid; iron supplements without folic acid

Additional comparator for KQs 1b, 1c, 2b: Lower or higher dose of folic acid supplementation

KQs 1a, 1b, 2a: Lower or higher dose of folic acid supplementation; folic acid vs. other active comparators

KQs 1c, 2b: Folic acid vs. other active comparators

Outcomes Neonatal outcomes: Neural tube defects

Harms from treatment:

  • Twinning
  • Colorectal cancer or other reported cancers
  • Masking of vitamin B12 deficiency
  • Vitamin B6 deficiency
  • Other reported neonatal, fetal, or maternal harms
Outcomes not specified in inclusion criteria
Timing Supplementation initiated before index pregnancy or in the first trimester Supplementation initiated after the first trimester of pregnancy
Settings Developed countries categorized as “Very High” by the Human Development Index (as defined by the United Nations Development Program) Countries not categorized as “Very High”
Study designs Efficacy (KQ 1): RCTs, CCTs, cohort, or case-control studies

Harms (KQ 2): RCTs, CCTs, or observational studies (case series, cohort, registry data)

Commentaries, editorials, case reports
Sample size More than 50 50 or less
Quality Good and fair quality Poor quality
Language English Non-English studies

Abbreviations: CCT = controlled clinical trial; KQ = key question; RCT = randomized, controlled trial.

AHRQ Publication No. 14-05214-EF-1
Current as of July 2014


Internet Citation:

U.S. Preventive Services Task Force. Folic Acid Supplementation for the Prevention of Neural Tube Defects: Draft Research Plan. AHRQ Publication No. 14-05214-EF-1. http://www.uspreventiveservicestaskforce.org/draftresplan2.htm



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