about live birth data

A Live Birth is defined as 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.

DATA SOURCE

Original source:Vital Statistics, Ontario Office of the Registrar General (ORG).
Cite as: Ontario Live Birth Database, 1986-2015, Office of the Registrar General. IntelliHEALTH Ontario, Ministry of Health and Long-Term Care.

METHODS

Data Collection Methods

• Information on live births is collected by the Office of the Registrar General (ORG), using the parent birth registration form and the Physician Notice of Birth or Stillbirth form (PNOB).
• Live birth registration is required by law and can now be done on-line through ServiceOntario if certain conditions are met.

Data Analysis Methods

• Data are based on geographic place of residence of the infant and not location of the live birth.
• Rates and proportions based on counts less than five (5) are suppressed.
• Births to out-of-province mothers have been excluded from analyses and may affect areas bordering Quebec and Manitoba.
• Rates are calculated based on the current Association of Public Health Epidemiologists in Ontario (APHEO) core indicator recommendations:
  • The denominator for rates may be: all live births, all live births among a specific age group, all births (including live births and stillbirths) or all pregnancies (including live births, stillbirths and therapeutic abortions). The denominator will depend on the indicator being examined.
  • Due to changes in registration practices of births at the borderline of viability, both crude rates and birth weight-specific rates should be considered.
• Includes live births with birth weight less than 500 grams. There has been an observed increase in the number of registered live births with a birth weight of less than 500 grams across Canada. For several years, these were not included in the count of live births; however, these very low birth weight births were once again included in the data.
• Region of birth of mother is defined based on the mother’s country of birth. Countries included in each of the categories are as follows:

LIMITATIONS

• The information within the Vital Statistics dataset is provided by both the parents (birth registration form) and the Physician Notice of Live Birth or Stillbirth form (PNOB). Both forms must be received by the Office of the Registrar General for the birth to be registered.
• Although live birth registration is required by law, changes in registration practices and the institution of registration fees decreased the proportion of births which were registered in the period between 1991 and 1997, when approximately 1% of live births were unregistered. Unregistered births were more likely within urban populations and among younger mothers and lower birth weight births. Municipal fees have been eliminated so that this is no longer an issue.
• The number of births registered in some areas changed dramatically starting in 1991 when the Office of the Registrar General moved from Toronto to Thunder Bay.
• Data using the parent registration form may be subject to recall bias.
• There are possible errors in the birth data file related to assignment of municipality of residence/census subdivision of the mother.
• The duration of pregnancy field has been noted to have some problems. Up until 1990 the Office of the Registrar General used the PNOB form as a gold standard for entering gestation age when the two forms disagreed. However, in 1990 the Office of the Registrar General stopped using the PNOB as the gold standard and switched to using the parent's form. As of June 1998, the Office of the Registrar General has switched back to using the PNOB as the gold standard. For the data from 1990 to 1998, the Office of the Registrar General undertook a project to review gestation age and update discrepancies using the PNOB. Unfortunately, currently accessible data do not contain this ‘corrected’ variable and therefore calculation of pre-term births will likely result in overestimates.
• Several data quality concerns have been identified with the Ontario live birth file:
  • underreporting of live births when linked to infant death records;
  • underreporting of stillbirths in 1990;
  • fluctuations in proportions of infants with birth weight < 500 grams suggests underreporting or misclassification of borderline viable infants;
  • in multiple births, not all infants are always accounted for;
  • duplicate and late registrations of births;
  • missing analytical variables; and
  • no copy of the original information to verify and/or correct these errors.

REFERENCES AND RESOURCES

1. Association of Public Health Epidemiologists in Ontario (APHEO). Vital Statistics Live Birth Data. 2013.
2. Woodward GL, Bienefeld MK, Ardal S. Under-reporting of Live Births in Ontario: 1991-1997. Central East Health Information Partnership. Can J Pub Hlth 2003; 94(6) Nov-Dec:463-467.
3. Ennis SL, Woodward GL, Ardal S. Low Birth Weight: Troubling Trend or Misguided Measure (Extended Mix): A CEHIP Discussion Paper. Central East Health Information Partnership, May 2000.
4. Woodward GL, Ardal S. Data Quality Report: Effect of Residence Code Errors on Fertility Rates. Central East Health Information Partnership, July 2000.
5. Health Canada. Perinatal Health Indicators for Canada: A Resource Manual. Ottawa: Minister of Public Works and Government Services Canada, 2000.
6. Joseph KS, Kramer MS. Recent trends in Canadian infant mortality rates: the effect of changes in registration of live newborns weighing less than 500g. Can Med Assoc J 1996; 155:1047-52.

Last updated: July 10, 2019

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