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6B Folic Acid Supplementation

Description | Specific Indicators | Ontario Public Health Standards | Corresponding Indicator(s) from Statistics Canada and CIHI | Corresponding Indicators from Other Sources | Data Sources |  Survey Questions | Alternative Data Sources | Analysis Check List | Method of Calculation |  Basic Categories | Indicator Comments | Definitions | Cross-References to Other Indicators | Cited References | Other References  | Changes Made | Acknowledgements


  • The proportion of women taking a folic acid supplement prior to or during pregnancy

Specific Indicators

  • Proportion of women taking folic acid supplementation prior to pregnancy
  • Proportion of women taking folic acid supplementation prior to and during pregnancy
Ontario Public Health Standards (OPHS)
The Ontario Public Health Standards (OPHS) establish requirements for the fundamental public health programs and services carried out by boards of health, which include assessment and surveillance, health promotion and policy development, disease and injury prevention, and health protection. The OPHS consist of one Foundational Standard and 13 Program Standards that articulate broad societal goals that result from the activities undertaken by boards of health and many others, including community partners, non-governmental organizations, and governmental bodies. These results have been expressed in terms of two levels of outcomes: societal outcomes and board of health outcomes. Societal outcomes entail changes in health status, organizations, systems, norms, policies, environments, and practices and result from the work of many sectors of society, including boards of health, for the improvement of the overall health of the population. Board of health outcomes are the results of endeavours by boards of health and often focus on changes in awareness, knowledge, attitudes, skills, practices, environments, and policies. Boards of health are accountable for these outcomes. The standards also outline the requirements that boards of health must implement to achieve the stated results.

Outcomes Related to this Indicator

  • Societal Outcomes (Reproductive Health): An increased proportion of individuals in their reproductive years are physically, emotionally, and socially prepared for conception.
  • Board of Health Outcome (Reproductive Health): The board of health is aware of and uses epidemiology to influence the development of healthy public policy and its programs and services for the promotion of reproductive health.
  • Board of Health Outcome (Foundational Standard): The public, community partners, and health care providers are aware of relevant and current population health information.

Assessment and Surveillance Requirements Related to this Indicator

  • Reproductive Health (Requirement #1): The board of health shall conduct epidemiological analysis of surveillance data... in the area of preconception health.

Corresponding Health Indicator(s) from Statistics Canada and Canadian Institute for Health Information (CIHI)
  • None 

Corresponding Health Indicator(s) from Other Sources

  • None
Data Sources (see Resources: Data Sources)

Numerator & Denominator: BORN Information System
Original source: Better Outcomes Registry Network (BORN) Ontario
Distributed by: Better Outcomes Registry Network (BORN) Ontario
Suggested citation (see Data Citation Notes): BORN Information System [years], Date Extracted: [date].

Survey Question(s)  

Data Source

BORN Encounter(s)

Data Element

Response Categories



Antenatal General

Antenatal Specialty

Maternal use of folic acid prior to and during pregnancy


Preconception only

During pregnancy only

Preconception and during pregnancy




Alternative Data Source(s) (see Resources: Data Sources)

Numerator & Denominator: Canadian Community Health Survey (CCHS)
Original source: Statistics Canada
Distributed by: Ontario Ministry of Health and Long Term Care (MOHLTC)
Suggested citation (see Data Citation Notes): Canadian Community Health Survey [years], Statistics Canada, Share File, Ontario Ministry of Health and Long Term Care

Survey Question(s)

The CCHS Maternal Experiences module is only asked of females aged 15 to 55, excluding proxy interviews. Women must have responded "yes" to the question "Have you given birth in the past 5 years?" (stillbirths excluded) to be asked the question on folic acid.

Data Source



Response Categories




Maternal Experiences (MEX)

Did you take a vitamin supplement containing folic acid before your (last) pregnancy, that is, before you found out that you were pregnant?

1 Yes

2 No










Numerator & Denominator: Rapid Risk Factor Surveillance System (RRFSS)
Original source: Public Health Unit
Distributed by: Public Health Unit
Suggested citation (see Data Citation Notes): RRFSS [month, year - month, year], Date Extracted: [month, year]

Survey Question(s)

The RRFSS Reproductive Health I and II Modules are only asked of females aged 18-49 who are currently pregnant (rh1=1) OR have had a baby in the past 5 years (rh2=1). 

Data Source



Response Categories



Reproductive Health I & II (optional from 2003-2011)

Did you take a vitamin supplement containing folic acid BEFORE you became pregnant this most recent time?

1 yes

5 no (includes "I started as soon as I became pregnant")

8 don' t know

9 refused


Analysis Check List

  • Public Health Units access BORN data through public health reports and data cubes.
  • Please refer to the BORN Information System resource for more information about the data.
  • It is recommended that public health units use the Share File provided by the Ministry of Health and Long-Term Care rather than public use file (PUMF) provided by Statistics Canada. The Share File has a slightly smaller sample size because respondents must agree to share their information with the province to be included; however, the share file has more variables and fewer grouped categories within variables. The Share File is a cleaner dataset for Ontario analysis because all variables that were not common content, theme content or optional content for Ontario have been removed. There may be slight differences between results from the share file and data published on the Statistics Canada website for the Health Indicators because rates calculated for Health Indicators use the master CCHS data file.
  • Not applicable respondents should be excluded; however, it is important to understand who these respondents are from the questionnaire skip patterns to be able to describe the relevant population.
  • Users need to consider whether or not to exclude the ‘Refusal, 'Don't Know' and ‘Not Stated' response categories in the denominator. Rates published in most reports, including Statistics Canada's publication Health Reports generally exclude these response categories. In removing not stated responses from the denominator, the assumption is that the missing values are random, and this is not always the case.This is particularly important when the proportion in these response categories is high.
  • Estimates must be appropriately weighted (generally the share weight for the CCHS) and rounded.
  • Users of the CCHS Ontario Share File must adhere to Statistics Canada's release guidelines for the CCHS data when publishing or releasing data derived from the file in any form. Refer to the appropriate user guide for guidelines for tabulation, analysis and release of data from the CCHS. In general, when calculating the CV from the share file using the bootstrap weights, users should not use or release weighted estimates when the unweighted cell count is below 10. For ratios or proportions, this rule should be applied to the numerator of the ratio.  Statistics Canada uses this approach for the tabular data on their website. When using only the Approximate Sampling Variability (CV) lookup tables for the share file, data may not be released when the unweighted cell count is below 30. This rule should be applied to the numerator for ratios or proportions.  This provides a margin of safety in terms of data quality, given the CV being utilized is only approximate.
  • Before releasing and/or publishing data, users should determine the CV of the rounded weighted estimate and follow the guidelines below:
    • Acceptable (CV of 0.0 - 16.5%) Estimates can be considered for general unrestricted release. Requires no special notation.
    • Marginal (CV of 16.6 - 33.3%) Estimates can be considered for general unrestricted release but should be accompanied by a warning cautioning subsequent users of the high sampling variability associated with the estimates. Such estimates should be identified by the letter E (or in some other similar fashion).
    • Unacceptable (CV greater than 33.3%) Statistics Canada recommends not to release estimates of unacceptable quality. However, if the user chooses to do so then estimates should be flagged with the letter F (or in some other fashion) and the following warning should accompany the estimates: "The user is advised that...(specify the data) not meet Statistics Canada's quality standards for this statistical program. Conclusions based on these data will be unreliable and most likely invalid". These data and any consequent findings should not be published. If the user chooses to publish these data or findings, then this disclaimer must be published with the data.
  • Caution should be taken when comparing the results from Cycle 1.1 (2000/01) to subsequent years of the survey, due to a change in the mode of data collection.  The sample in Cycle 1.1 had a higher proportion of respondents interviewed in person, which affected the comparability of some key health indicators.  Please refer to for a full text copy of the Statistics Canada article entitled "Mode effects in the Canadian Community Health Survey: a Comparison of CAPI and CATI".
  • Users should refer to the most recent RRFSS Manual of Operations for a complete list of RRFSS analysis guidelines.
  • Denominator Data - cell size less than 30 not to be released (based on unweighted data).
  • Numerator Data - cell size less than 5 not to be released (based on unweighted data).
  • Coefficients of variation (CV) should be calculated for every estimate. The following categories determine the release of the data:
    • CV between 0 and 16.5:  estimate can be released without qualification.
    • CV between 16.6 and 33.3:  estimate can be released with qualification:  interpret with caution.  High variability.
    • CV greater than 33.3:  estimate should not be released, regardless of the cell size.
  •  95% confidence intervals (C.I.) should accompany all released estimates.  In general the simple computation of the C.I. for a proportion assuming SEp = sqrt(pq/n) and CI95% = p +/- 1.96*SEp is sufficient. However, if estimates are close to 0 or 100% and the simple computation confidence intervals include values less than zero or greater than 100 then the Fleiss 2nd edition computation for skewed estimates should be employed.
  • Weighting:
    • General household weight will be applied for questions related to the individual.
    • Household weight is to be applied for questions about households when we wish to determine the population/number of people affected.
    • Household weight is not to be applied for child proxy questions (bicycle helmet use, car seat safety), dog and cat immunization modules, or other questions that relate to the household rather than the respondent.
    • Household weights are not required to be recalculated for sub-population based questions; for example mammography in women ages 35+ years and 50-74 years.
    • If the weights supplied with the data set (health unit wave specific, health unit cumulative total, all health units combined wave specific, all health units combined cumulative total) are not appropriate for the required analysis, then a time-specific weight must be calculated.  For example, a new weight is required for all seasonal modules.
  • If the cell size of ‘Don't Know' responses is 5% or greater, ‘Don't Know' responses should be included in the denominator of the analyses and reported separately.
  • If the cell size of ‘Refusal' responses is 5% or greater, ‘Refusal' responses should be included in the denominator of the analyses and reported separately.
  • When an indicator is being compared between groups (e.g. health units, time periods, gender), if any one group has ‘Don't Know' and/or ‘Refusal' responses that are 5% or greater, ‘Don't Know' and/or ‘Refusal' responses should be included in the denominator of the analyses and reported separately for all groups.
  • A provincial sample is not available with the RRFSS.
  • Refer to the RRFSS Data Dictionaries at for more information about module questions and indicators.
Method of Calculation

Proportion of women taking a folic acid supplement prior to pregnancy

total* number of women who took a folic acid supplement before pregnancy

x 100

total number of women who had given birth

*BORN data: Include women who reported "preconception only" OR "preconception and during pregnancy" use of folic acid supplements.

Proportion of women taking a folic acid supplement prior to and during pregnancy 

number of women who took a folic acid supplement prior to and during pregnancy

x 100

total number of women who had given birth


Basic Categories
  • Age groups for age-specific rates: 15-24, 25-34, 35-49
  • Geographic areas of residence:
    • BORN, CCHS data: Ontario, public health unit
    • RRFSS data: RRFSS - participating health units that chose the Reproductive Health I & II Module (varies by wave, check documentation).
Indicator Comments
  • The Society of Obstetricians and Gynecologists of Canada (SOGC) recommends folic acid supplementation for women planning a pregnancy, and throughout pregnancy, with higher doses recommended for at risk women during the first trimester (1). CCHS and RRFSS ask about folic acid supplementation prior pregnancy but do not capture folic acid supplementation during pregnancy. BORN captures use of folic acid during preconception only, during pregnancy only, and during both preconception and pregnancy.  
  • Considering that the level of intake of folic acid from fortified foods is estimated to be no more than 100 to 200 µg per day, and recognizing that many pregnancies are unplanned, all women who could become pregnant should take a multivitamin containing 400 µg (0.4 mg) of folic acid daily (2).
  • In November 1998, the Canadian government mandated the fortification of white flour and pasta products labelled "enriched" with folic acid. This was expected to add about 0.1 mg (100 µg) of folic acid daily to the average diet (3).
  • The overall prevalence of neural-tube defects at birth in seven Canadian provinces (Ontario excluded) decreased from 1.58 per 1000 births before the fortification mandate, to 0.86 per 1000 births during the full-fortification period, a 46% reduction (4).
  • Although folic acid supplementation has been shown to reduce the rate of neural tube defects, it does not eliminate them altogether (5).
  • The launch of the BORN Information System in early 2012 created the capability to collect folic acid supplementation data from the Antenatal General, Antenatal Specialty, Labour and Birth Mother encounters, thus providing more complete coverage of folic acid supplementation in pregnant women than surveys of the general population. Information about the completeness and quality of the BORN data will become available after a suitable period of data collection has occurred.
  • Since RRFSS and CCHS data are self-reported retrospectively, folic acid supplementation rates are subject to recall bias.
  • Note that assessment of folic acid supplementation may not be an accurate measure of adequate intake. It is not known whether supplementation was at the recommended level; as well, those reporting no supplementation may have had adequate folate intake through a healthful diet.
  • Since CCHS collects information on women aged 15 to 55 who have given birth in the past 5 years, women theoretically may have been as young as 10 years or as old as 55 years of age at time of infant's birth.
  • RRFSS collects information on women aged 18 to 49 who have given birth in the past 5 years, therefore women theoretically may have been as young as 13 years or as old as 49 years of age at the time of infant's birth.
  • RRFSS data for this indicator for waves 1 to 5 (data from 2001) excluded females who were currently pregnant and did not have a baby in the past 5 years (rh2=5) and, as such, should not be used due to the lack of consistency with future years that included pregnant females at the time of the survey.
  • Folic acid – a naturally occurring B vitamin (B9). It is necessary for the breakdown and use of protein, and the formation of nucleic acids and heme. Need for folic acid is increased during pregnancy, in infancy, and by stress. Low intake of folic acid (folate) in pregnant women is associated with neural tube defects. Health Canada recommends that all women of childbearing age increase their daily intake from the 0.2 mg recommended daily intake for adults to 400 µg (0.4 mg) daily. Supplementation of a woman’s diet with folic acid should occur from at least three months before conception and continue throughout the pregnancy (2). 
  • Neural tube defect – a genetic malformation involving the skull and spinal cord. Neural tube defects are primarily caused by a failure of the neural tube to close during development of the embryo. Diagnostic tests (maternal serum screening, amniocentesis, and ultrasound) are available but not 100% sensitive or specific. Neural tube defects include: anencephalus, spina bifida, encephalocele, hydrocephalus, and other anomalies of the nervous system. Spina bifida occulta is not included in this category of anomalies.
  • Planned pregnancy – one that is intended. Optimally, a planned pregnancy is one in which the prospective parents anticipate conception and prepare for it for at least three months by removing potential risk factors from their lives, e.g., eliminating alcohol, tobacco, and other over-the-counter and illegal drugs, and hormone-based contraceptives; educating themselves about pregnancy and parenthood; being tested and treated for communicable diseases, etc.
Cross-References to Other Indicators
Cited References
  1. Society of Obstetricians and Gynecologists of Canada and Motherisk. Pre-conceptional vitamin/folic acid supplementation 2007: The use of folic acid in combination with a multivitamin supplement for the prevention of neural tube defects and other congenital anomalies. Joint SOGC-Motherisk Clinical Practice Guideline. No. 201, December 2007.  Available from:
  2. Public Health Agency of Canada. Prenatal Nutrition Guidelines for Health Professionals - Folate Contributes to a Healthy Pregnancy, 2010. Available from: Accessed: April 17, 2011.
  3. Government of Canada. Regulatory Impact Analysis Statement SOR/98-550, 2003. Canada Gazette;132,3029-3033.
  4. De Wals P et al. Reduction in Neural-Tube Defects after Folic Acid Fortification in Canada. N Engl J Med. 2007;357:135-42.
  5. Heseker HB, Mason JB, Selhub J, Rosenberg IH, and Jacques PF. Not all cases of neural-tube defect can be prevented by increasing the intake of folic acid. Br J Nutr. 2009; 102;173-180.

Other References

  1. Health Canada. Perinatal Health Indicators for Canada: A Resource Manual. Ottawa: Minister of Public Works and Government Services Canada, 2000. Available from: Accessed: September 14, 2012.
  2. Ray JG, Vermeulen MJ, Boss SC, Cole DEC. Declining Rate of Folate Insufficiency among Adults following Increased Folic Acid Food Fortification in Canada. Can J Public Health. 2002;93(4):249-253.
  3. Reisch HS, Flynn MAT. Folic Acid and the Prevention of Neural Tube Defects (NTDs): Challenges and Recommendation for Public Health. Can J Public Health. 2002;93(4):254-258.
  4. Morin P, De Wals P, St-Cyr-Tribble D, Niyonsenga T, Payette H. Pregnancy Planning: A Determinant of Folic Acid Supplements Use for the Primary Prevention of Neural Tube Defects. Can J Public Health. 2002;93(4):259-263.
Changes Made


Type of Review (Formal or Ad hoc)

Changes made by


April 27, 2004



  • Indicator completed on the website.

March 23, 2012


Reproductive Health Sub-group

  • Added BORN as a "Data Source" and made CCHS, RRFSS  "Alternate Data Sources".
  • Added specific indicators that reflect information available in BORN.
  • Updated method of calculation to reflect the specific indicators.
  • Updated "Indicator Comments" and references.



Lead Author(s)

  • Jessica Deming, Region of Waterloo Public Health
  • Sandy Dupuis, Niagara Region Public Health
  • Natalie Greenidge, Public Health Ontario

Contributing Author(s)

  • Reproductive Health Work Group


  • Sarah Collier, Toronto Public Health
  • JoAnne Fernandes, Peel Public Health
  • Caitlin Johnson, York Region Community and Health Services
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