Canadian Environmental Health Atlas

Understanding Our Environment is Key to Promoting Health and Preventing Disease

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The Impact of Toxins on Preterm Birth

The Impact of Toxins on Preterm Birth



Babies who are born preterm – which is 3 or more weeks before their due date - are more likely to die in the first year of life or develop heart disease, diabetes or have trouble learning.

Every year about 15 million babies are born too soon. In some countries, fewer than 10% of babies are born preterm; in others, 10% to 15%, and still others, as many as 18% are born too soon. We can see that kind of variation within countries too.  Because PTB occurs less frequently in many places, it gives us hope that we can prevent it.

Preterm birth, which is a key barometer for the health of a population, can be due to infection, poor nutrition, or having twins or triplets, but these only account for about one-third of babies born preterm.

Environmental toxins can also tip the scales and increase the number of children born too soon. Lets look at how toxins can alter the typical distribution of pre-term births.

In England, women who had higher levels of lead in their blood were two-times more likely to give birth too soon. Reducing exposure to toxins, like tobacco smoke, can substantially reduce PTB. In Scotland, preterm births declined by 15% in women who didn’t smoke after smoking was banned in public places. This is staggering; it shows that reducing low-level exposures to an environmental toxin can result in a big reduction in PTB.

Other ubiquitous toxins, including air pollution and contaminants in our food, like PFCs, are risk factors for preterm birth. Because these toxins are insidious or invisible, they are easily dismissed or ignored, but they can have grave effects on pregnancy and a child’s development.

While a single toxin may shorten pregnancy by only 3 to 7 days, the cumulative impact of exposure to many toxins can be substantial. Many women are unknowingly exposed to SHS, lead and PFCs as well as other toxins linked with PTB. In the United States, which has the most extensive biomonitoring program in the world, 17% of pregnant women are simultaneously exposed to high levels of 3 or more of these toxins.

If many, or even most preterm births are due to the cumulative impact of many subtle risk factors - each of which may reduce the duration of pregnancy by 3 to 7 days - then we can prevent many babies from being born too soon.

Little things add up. Little things matter. 


1. Eat fresh or frozen foods. Choose organic, if possible.
2. Avoid packaged foods and steer clear of heavily processed foods.
3. If you are pregnant, or planning to become pregnant, eat fish with low levels of mercury.
4. Don’t use pesticides in and around your home.
5 Check your home for lead hazards, especially if it was built before 1960.
6. Frequent cleaning of floors and surfaces may help reduce exposure to lead, flame retardants and other toxins in house dust.
7. The key to reducing our exposure to toxic chemicals is to require that chemicals be tested for toxicity before they are put on the market.
8. Advocate for policies to prevent exposures to toxic chemicals. Support efforts to ban pesticide use and smoking in your community.