MHLU - Health Status Resource

Birth Outcomes

Birth Outcomes

Key Findings: 

    Multiple Births

  • The rate of multiple births has increased steadily from 2003 to 2009 in Ontario. The rates for Middlesex-London appear for the most part to follow the trend for Ontario and the Peer Group. Fluctuations seen with the Middlesex-London rates are expected based on the relatively smaller numbers of multiple births (Fig. 9.13).
  • Low Birth Weight

  • The low birth weight rate in Middlesex-London was 6.1% in 2009. The rates over time are similar to that of Ontario and the Peer Group and appear to increase slightly over this time period (Fig. 9.14).
  • SGA

  • From 2003 to 2006, the percent of small-for-gestational age (SGA) babies in Middlesex-London was somewhat lower than those in Ontario and similar to the Peer Group.  In 2007, however, the rate in Middlesex-London rose to 8.6% almost reaching the Ontario rate of 8.8% (Fig. 9.15). 
  • The SGA rate was highest for those babies whose mothers were youngest ie. ages 15 to 19 at 10.4% in Middlesex-London. Rates declined to 6.7% at ages 30 to 34 and then rose to 9.0% at ages 40 to 44 (Fig. 9.16). 
  • In Middlesex-London, SGA rates were lower than those for Ontario for maternal age groups up until about age 35 after which rates were more similar to Ontario. SGA rates across age groups were similar to those for the Peer Group (Fig. 9.16).
  • LGA

  • LGA rates declined slightly from 2003 to 2007 in Middlesex-London, Ontario and the Peer Group (Fig. 9.17).
  • In Middlesex-London, LGA rates were higher than those in Ontario and generally lower than those in the Peer Group. Most of the differences, however, were not statistically significant (Fig. 9.17).
  • LGA rates were lowest for teen moms and increased steadily to ages 40 to 44. In Middlesex-London, a 35 to 39 year-old mom was 1.8 times more likely than a 15-19 year-old mom to have a LGA baby (Fig. 9.18).
  • Middlesex-London LGA rates for maternal age groups were similar to those of Ontario and the Peer Group in the youngest age groups, especially ages 15 to 19. With older age groups, Middlesex-London rates rose beyond those of Ontario but not quite as high as for the Peer Group (Fig. 9.18).
  • Preterm Births

  • Preterm birth rates in Middlesex-London were similar to Ontario and the Peer Group for the most part at 8.2% of live births in 2009 (Fig. 9.19).
  • In general, preterm birth rates have been relatively stable from 2006 to 2009 (Fig. 9.19). Although Middlesex-London’s rates appear to have decreased over this time period, the decline is not statistically significant (Fig. 9.19).
  • Preterm birth rates for singleton babies were highest for mothers ages 40 and older and those ages 15 to 19 to a lesser extent. Mothers ages 30 to 34 had the lowest rates (Fig. 9.20). 
  • SGA, LGA and Preterm Births

  • For the maternal age group 20 to 24, rates of SGA and LGA of singleton babies are equally prevalent and somewhat higher than preterm birth; the younger maternal age group (15-19), however, shows a somewhat higher rate of SGA than LGA and preterm birth (Fig. 9.21).
  • Teen mothers (ages 15 to 19) of singleton babies experience the highest SGA rate and lowest LGA rate of all maternal age groups. Preterm birth rates for teen moms are the second highest of all age groups (Fig. 9.21).
  • Maternal ages older than 20 to 24 show more prevalent and increasing rates of LGA in singletons as SGA rates decline until ages 30 to 34 where they begin to rise again thereafter (Fig. 9.21).
  • Singleton babies of mothers ages 35 to 39 are twice as likely to be large-for-gestational age than small-for-gestational age (Fig. 9.21).
Interpretive Notes

Rates of low birthweight, preterm birth, also known as prematurity, small-for-gestational age (SGA), also referred to as growth restriction, and large-for-gestational age (LGA) are birth outcomes associated with health problems and mortality in childhood and sometimes beyond. Most birth outcomes were analyzed using singletons only since multiple births are associated with very high rates of the former three birth outcomes and have been increasing over time. 

How this Indicator was Calculated: 
Ontario Public Health Standard: 

Population Health Assessment and Surveillance Protocol - Section 1

Jargon Explained

Low birth weight rate

Number of live births weighing less than 2500 grams (5 lbs, 8 oz) at birth per 100 live births.

Small-for-gestational age (SGA) rate

Number of singleton live births with a birth weight less than the 10th percentile of birth weights of the same sex and same gestational age in weeks, expressed as a percentage of live singleton births with gestational ages from 22 to 43 weeks.

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Large-for-gestational age (LGA)

Singleton live births with a birth weight more than the 90th percentile of birth weights of the same sex and the same gestational, expressed as a percentage of live singleton births with gestational ages from 22 to 43 weeks. 

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Preterm Birth Rate

Number of live births delivered before 37 completed weeks of gestation per 100 live births.