Low birth weight

What is it?

Low birth weight (LBW) is defined as a birth weight of less than 2,500 grams (5.5 pounds), regardless of gestational age. LBW rate refers to the number of babies born LBW , expressed as a percentage of all live births.

Why is it important?

Low Birth Weight has both short- and long-term consequences on health. These include higher risk of childhood illness, delays in motor development, and chronic diseases in adulthood such as diabetes and respiratory disease. A low birth weight may be the result of premature birth or restricted growth in-utero. Risk factors for LBW include maternal ages under 20 or over 35, smoking or illicit drug use during pregnancy, low socioeconomic status and multiple births (e.g. twins, triplets).

What does it mean?

In Toronto, 7.8% of all live births were LBW in 2016. Figure 1 shows that the LBW rate varies across Ontario and that the LBW rate in Toronto was higher than the rest of Ontario in 2016. Figure 2 shows that the LBW rate was significantly higher in the three lower income quintiles, as compared to the highest income quintile. This mean that babies born in low income areas are more likely to have a LBW. Figure 3 shows the LBW rate, for 2015 and 2016 combined, by Toronto neighbourhood. The rate ranged from 2.9% to 12.1% across the city. Neighbourhoods with higher LBW rates were clustered in the northwest and central east areas of the city. For some neighbourhoods, data is unavailable numbers were too small to release. Figure 4 shows that the LBW rate has remained relatively stable over time.

Figure 3: Low birth weight rate by neighbourhood, Toronto, 2015 and 2016 combined