To advance and promote the discipline and professional practice of epidemiology in Ontario public health units
Please click here to visit our new website




6B Age of Parent at Infant’s Birth

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

  • Age of parent as of the date of birth of their infant
Specific Indicators
  • Average age of mother
  • Average age of mother at birth of first infant 
  • Average age of father
  • Median age of mother
  • Median age of mother at birth of first infant
  • Median age of father
  • Proportion of births by age of mother
  • Proportion of births of first infant by age of mother
  • Proportion of births by age of father
Ontario Public Health Standards(s) 
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 
  • 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/or Surveillance Requirements Related to this Indicator  
  • The board of health shall conduct epidemiological analysis of surveillance data... in the area of reproductive health outcomes. 

Corresponding Health Indicator(s) from Statistics Canada and CIHI
  • Proportion of live births by age of mother in a calendar year (CANSIM Table 102-4503)
  • Mean age of mother at live birth in a calendar year (CANSIM Table 102-4504)

Statistics Canada CANSIM. Available from:
Indicators of Well-being in Canada: Family Life - Age of mother at childbirth. Available from:


Corresponding Indicator(s) from other Sources 
  • None
Data Sources (see Resources: Data Sources) 
Note that 3 data sources are listed for use: 1) Vital statistics 2) Hospitalization and 3) BORN. The choice of data source will depend upon data quality within a health unit as well as data access and the specific analysis questions. For information related to the data sources, refer to the Data Source resources and the Reproductive Health Core Indicators Documentation Report.

Alternative 1
Numerator and Denominator: Vital Statistics Live Birth Data - Live Births
Original source: Vital Statistics, Office of the Registrar General (ORG)
Distributed by: Ontario Ministry of Health and Long-Term Care (MOHLTC): IntelliHEALTH ONTARIO (IntelliHEALTH)
Suggested citation (see Data Citation Notes): Ontario Vital Statistics Live Birth Data [years],  Ontario Ministry of Health and Long-Term Care, IntelliHEALTH ONTARIO, Date Extracted: [date].

Alternative 2
Numerator and Denominator:
Hospitalization Data
Original source:
Discharge Abstract Database (DAD), Canadian Institute for Health Information (CIHI)
Distributed by: Ontario Ministry of Health and Long-Term Care (MOHLTC): IntelliHEALTH ONTARIO (IntelliHEALTH)
Suggested citation (see Data Citation Notes): Inpatient Discharges [years], Ontario Ministry of Health and Long-Term Care, IntelliHEALTH ONTARIO, Date Extracted: [date]. 

Alternative 3
Numerator and Denominator: BORN Information System Live Births
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].

Alternative 4*
Vital Statistics Stillbirth Data
Original source:
Vital Statistics, Office of the Registrar General (ORG)
Distributed by: Ontario Ministry of Health and Long-Term Care (MOHLTC): IntelliHEALTH ONTARIO (IntelliHEALTH)
Suggested citation (see Data Citation Notes): Ontario Stillbirth Data [years], Ontario Ministry of Health and Long-Term Care, IntelliHEALTH ONTARIO, Date Extracted: [date].

*It may be informative to examine stillbirths by maternal age. Due to data quality issues, it is recommended that stillbirths not be examined by paternal age. Please refer to indicator comments below.


Alternative Data Sources(s) 
  • None
Analysis Check List  
  • The IntelliHEALTH licensing agreement does not require suppression of small cells, but caution should be used when reporting at a level that could identify individuals, (e.g. reporting at the postal code level by age and sex). Please note that privacy policies may vary by organization. Prior to releasing data, ensure adherence to the privacy policy of your organization.
  • Aggregation (e.g. combining years, age groups, categories) should also be considered when small numbers result in unstable rates.
  • Analyze by mother's residence, not place of birth. Note that no variable exists for father's residence, therefore indicators of father's age at infant's birth should also be analyzed by mother's residence.
  • HELPS Data: Historically, PHUs obtained data for live births, stillbirths, therapeutic abortions, congenital anomalies, and deaths from the Ministry of Health through HELPS (the HEalthPlanning System). Although these data are no longer commonly used, some PHUs may still be accessing these data files. Information about the data can be found in the HELPS Data Source resource.
Vital Statistics Live Births 
  • Use Live Birth data source under Vital Statistics information map.
  • Select a measure under Measures data item. "#LB" gives the number of births (live births) to Ontario mothers who gave birth in ON excluding ON mothers who gave birth outside ON.
  • When selecting Maternal PHU, exclude births to "out-of-province" mothers.
  • "Birth Type" under Birth Information may be used to select whether the birth is singleton, twin, or other.
  • Under Mother's Information, select "Mother's Age (yrs)". If calculating an indicator of age at "first birth" also select "Live Births to Mother" and "Stillbirths to Mother".
  • If calculating an indicator of paternal age, under Other Parental Information, select "Father's Age".
To derive "first birth" status, include the following scenarios as "first births" and exclude all others from calculation of the indicator: 
Birth Type

Number of Live Births to Mother
(includes current birth)

Number of Stillbirths to Mother
(includes stillbirth)

Singleton (live birth)



Twins, all live birth



Twins, 1 live birth, 1 stillbirth



Triplets, all live birth



Triplets, 1 live birth, 2 stillbirths



Triplets, 2 live births, 1 stillbirth



Quadruplets, all live birth



  • A predefined report has been created under the Standard Reports folder, ‘05 Inpatient Discharges', 'Hospital Births - OBS deliveries - maternal age'. This report can be modified, renamed and saved under your own folder.
  • The report provides maternal age and the number of previous live births. Since mean and median age cannot be calculated in Intelliheath, the data and instructions for exporting to Excel are provided in this report as part of the third tab. 
  • Unlike Vital Statistics, the current birth is not included in the Previous Live Births field. To identify first births, Previous Live Births = 0.
  • The Previous Live Births field became available in intelliHEALTH data in 2006; however, there are a high number of unknowns in 2006. Begin analysis for calendar year 2007+.
  • Paternal age is not available in hospitalization data.
  • 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.
Method of Calculation

Mean Age of Mother (or Father) at Birth

sum [number of live births  at each age * age of mother (or father)]


total number of live births

Mean age = (100*14 + 115*15 + 280*16 + 700*17 + 1200*18 + 2000*19 .....98*44)¸ 10,179

Median Age of Mother (or Father) at Birth

The middle age observed for the period under study (½ of observations are higher and ½ are lower when rank ordered) 

total number of live births for mother's (or father's) age group

x 100

total number of live births


Proportion of Births by Age of Mother (or Father)

total number of live births for mother's (or father's) age group

x 100

total number of live births

Basic Categories
  • Geographic areas of patient residence:
    • Vital Statistics data: Ontario, public health unit, municipality, and smaller areas of geography based on aggregated postal code.
    • BORN data: Ontario, public health unit
  • Maternal age groups: <20; 20 - 24; 25 - 29; 30 - 34; 35 - 39; 40 - 44; >=45
  • Paternal age groups:<20; 20 - 24; 25 - 29; 30 - 34; 35 - 39; 40 - 44; 45 - 49; >=50
  • Gestational age
  • Parity (derived from birth type, number of live births and number of stillbirths)
Indicator Comments
  • Average age of mothers giving birth to their first child is increasing in Ontario (1).
  • Increasing age of mother at first birth affects the total fertility rate.
  • Advanced maternal age is associated with is associated with increased risk of labour complications (2), pregnancy intervention such as caesarean delivery (2 - 4), and adverse birth outcomes such as stillbirth, preterm birth and small for gestational age (5).
  • Risk of schizophrenia increases with advanced paternal age (6, 7).  
  • Advanced maternal and paternal age are both associated with risk of autism spectrum disorder (8, 9), bipolar affective disorder (10), pre-eclampsia/pregnancy induced hypertension (11, 12), some congenital anomalies (13, 14), early and late fetal death (15-17), and stillbirth (18, 19).
  • Paternal age is missing for up to 4% of live births and up to 96% of stillbirths in the Vital Statistics data sources. It may be informative to examine stillbirths by age of mother but it is recommended that stillbirths not be examined by age of father.
  • No parity variable exists in the Vital Statistics Live Birth database. Therefore a measure of "first birth" must be derived as described in the table above. First birth indicators cannot be calculated for fathers, as variables for number of live births and number of stillbirths only exist for the mother; no measure of past number of live or stillbirths for fathers is available. 
  • No variable exists in the Live Births or Stillbirths datasets for father's residence, therefore indicators of father's age at infant's birth must be analysed by mother's residence. This method of analysis assumes that fathers reside in the same geographic area as the mother, which may not always be the case.
  • Median age is less sensitive to extreme values than is mean age and may be more stable for geographic areas with a small number of observations.
  • Registration fees initiated in some Census Subdivisions (CSDs) in 1996 may have reduced the number of infants registered, especially for low income and/or adolescent parents (20); however it is worth noting that registration fees have since been discontinued in Ontario. Please refer to the Timelines of Changes in Live Birth Registration in Ontario document for a description of changes in live birth registration in Ontario, including temporal changes in municipal fees.
  • The number of births registered in some CSDs changed dramatically starting in 1991 when the Office of the Registrar General moved from Toronto to Thunder Bay (21). Aggregation may be necessary for reliability.
  • Maternal age categories are available through BORN. Therefore, mean and median age of mother at infant's birth cannot be determined using BORN data. 
  • BORN does not routinely collect paternal age at infant's birth. Paternal age for live born or stillborn infants that had abnormal prenatal screening is included in BORN.
  • Maternal age at first live birth is available through BORN.
  • Congenital anomaly - a condition that results from an abnormality of structure, function or metabolism in one or more parts of the body, with potential to adversely affect health, development or function. Anomalies are present at birth and may be inherited genetically, acquired during gestation, or inflicted during birth. Also called a birth defect.
  • Live birth - the complete expulsion or extraction from its mother of a product of conception, irrespective of the duration of the pregnancy, which, after such separation, breathes or shows any other evidence of life such as heartbeat, umbilical cord pulsation, or definite movement of voluntary muscles, whether the umbilical cord has been cut or the placenta is attached. A live birth is not necessarily a viable birth.
  • Stillbirth - death prior to the complete expulsion or extraction from its mother of a product of conception, irrespective of the duration of pregnancy; the death is indicated by the fact that after such separation the fetus does not breathe or show any other evidence of life, such as beating of the heart, pulsation of the umbilical cord, or definite movement of voluntary muscles. Only fetal deaths where the product of conception has a birth weight of 500 grams or more or the duration of pregnancy is 20 weeks or longer are registered in Canada.
  • Parity - the number of total births (live births and stillbirths) a woman has experienced (22).
Cross-References to Other Indicators
  • None
Cited References  
  1. Statistics Canada. Mean age of mothers (live births), Ontario. CANSIM Table 102-4504. Available from:
  2. Luke B, Brown MB. Elevated risks of pregnancy complications and adverse outcomes with increasing maternal age. Hum Reprod. 2007;22(5):1264-72.
  3. Bayrampour H, Heaman M. Advanced maternal age and the risk of cesarean birth: a systematic review. Birth. 2010;37(3):219 - 25.
  4. Carolan M, Davey MA, Biro MA, Kealy M. Older maternal age and intervention in labor: a population-based study comparing older and younger first-time mothers in Victoria, Australia. Birth. 2011; 28(1)24- 29.
  5. Lisonkova S, Jansesen PA, Sheps SB, Lee SK, Dahlgren L. The effect of maternal age on adverse birth outcomes: does parity matter? J Obstet Gynaecol Can. 2010; 32(6):541 - 548.
  6. Miller B, Messias E, Miettunen J, Alaraisanen A, Jarvelin MR, Koponen H, et al. Meta-analysis of paternal age and schizophrenia risk in male versus female offspring. Schizophr Bull. 2011; 27(5):1039-47.
  7. Torrey EF, Buka S, Cannon TD, Goldstein JM, Seidman LJ, Liu T, Hadley T, et al. Paternal age as a risk factor for schizophrenia: How important is it? Schizophra Res. 2009; 115:1 - 5.
  8. Croen LA, Najjar DV, Fireman B, Grether JK. Maternal and paternal age and risk of autism spectrum disorders. Arch Pediatr Adolesc Med. 2007;161: 334 - 340.
  9. Durkin MS, Maenner MJ, Newschaffer CJ, Lee LC, Cunniff CM Daniels JL, et al. Advanced paternal age and risk of autism spectrum disorder. Am J of Epidem. 2008; 168(11):1268 - 76.
  10. Menezes PR, Lewis G, Ramussen F, Zammit S, Sipos A, Harrison GL, et al. Paternal and maternal ages at conception and risk of bipolar affective disorder in their offspring. Psychological Medicine. 2010; 40 (3): 477-85.
  11. Chen XK, Wen WS, Smith G, Leader A, Sutandar M, Yang Q, et al. Maternal age, paternal age and new-onset hypertension in late pregnancy. Hypertension in Pregnancy. 2006; 25: 217-27.
  12. Harlap S, Paltiel O, Deutsch L, Knaanie A, Masalha S, Tiram E, et al. Paternal age and preeclampsia. Epidemiology. 2002; 13(6): 660-7.
  13. Bille C, Skytthe A, Vach W, Knudsen LB, Nybo-Anderson AM, Murray JC, et al. Parent's age and the risk of oral clefts. Epidemiology. 2005; 16(3):311-16.
  14. Green, RF, Devine O, Crider KS, Olney RS, Archer N, Olshan AF, et al. Association of paternal age and risk for major congenital anomalies from the National Birth Defects Prevention Study, 1997 to 2004. Ann Epidemiol. 2010;20:241-49.
  15. Andersen AMN, Hansen KD, Andersen PK, Smith GD. Advanced paternal age and risk of fetal death: A cohort study. Am J Epidemiol, 2004; 160 (1): 1214-22.
  16. Maconochie N, Doyle P, Prior S, Simmons R. Risk factors for first trimester miscarriage - results from a UK-population-based case-control study. BJOG, 2007; 114:170-186.
  17. Kleinhaus K, Perrin M, Friedlander, Y, Paltiel O, Malaspina D, Harlap S. Paternal age and spontaneous abortion. Obstetrics & Gynecology, 2006; 108(2): 369-377.
  18. O'Leary CM, Bower C, Knuiman M, Stanley FJ. Changing risks of stillbirth and neonatal mortality associated with maternal age in Western Australia: 1984-2003. Paediatric and Perinatal Epidemiology, 2007. 21, 541-549.
  19. Huang L, Sauve R, Birkett N, Fergusson D, van Walraven C. Maternal age and risk of stillbirth: a systematic review. CMAJ, 2008; 178(2): 165-172.
  20. Bienefeld M, Woodward GL, Ardal S. Underreporting of live births in Ontario: 1991-1997. Central East Health Information Partnership, February 2001.
  21. Woodward GL, Ardal S. Data Quality Report: Effect of Residence Code Errors on Fertility Rates. Central East Health Information Partnership, July 2000.
  22. Last JM. A Dictionary of Epidemiology. 4th ed. New York: Oxford University Press; 2001.
Changes Made 


Type of Review-Formal Review or Ad Hoc?

Changes made by


Dec. 2, 2008



  • Changed recommended method of selecting deliveries from PHPDB from CMG codes to Patient Service Code.

March 29, 2012 - January 16, 2013


Reproductive Health Work Group

  • Added paternal age specific indicators.
  • Added corresponding indicators from Statistics Canada.
  • Added BORN data source
  • Major changes to analysis checklist, method of calculation, indicator comments and cited 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


  • Virginia McFarland, Grey Burce Health Unit
Treasurer/Secretary | Admin | Members Login