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The impacts of climate change hit Canada hard in recent years, from the deadly heat dome of 2021 to the country’s worst-ever wildfire season last summer. And those devastating environmental disasters provoked a lot of anxiety among pregnant individuals.
“Pregnancy, even without heat and smoke, is a time when symptoms of breathlessness are quite common and considered normal,” said midwife Zoë Hodgson, the clinical director at the Midwives Association of British Columbia. “But put the smoke and heat on top of that and people start to feel uneasy.”
Those concerns are rooted in some grim realities.
Pregnant individuals and children face “extreme health risks from climate catastrophes,” according to a report released this week by the World Health Organization (WHO) and other United Nations agencies.
The warning carries particular urgency as the globe continues to experience record-breaking temperatures, and scientists expect more climate-related disasters in the decades ahead.
“Climate change poses an existential threat to all of us,” said Dr. Bruce Aylward, a Canadian physician and epidemiologist and an assistant director general of the WHO, in a statement.
“But pregnant women, babies and children face some of the gravest consequences of all.”
Research links health with heat, air pollution
A growing body of research backs up those concerns.
Pregnant people exposed to extreme heat are at increased risk of developing life-threatening complications during labour and delivery, suggests a retrospective study published in the Journal of the American Medical Association in September. Researchers looked at more than 400,000 pregnancies over a decade in Southern California, and found that being exposed to extreme heat — days where the temperature was 35 degrees or higher — was associated with severe health issues.
Another research review, published in May in the Journal of Midwifery & Women’s Health, noted some of the mechanisms at play.
There are normal physiologic changes that occur during pregnancy, such as increased hormonal sensitivity and changes in circulation and blood volume.
These can reduce a pregnant individual’s ability to regulate their body temperature. Researchers said this also increases their susceptibility to adverse heat-related health effects.
For example, heat exposure can elevate a pregnant person’s core body temperature, speeding up the fetus’ heart rate or triggering early uterine contractions. Pregnancy also increases hydration needs, which hikes the risk of dehydration.
A Canadian analysis cited in the review also found a higher risk of placental abruption — a medical emergency that can kill both the pregnant person and fetus — among people exposed to maximum weekly temperatures of 30 C compared to maximum weekly temperatures of 15 C.
With the impacts of air pollution, a study published in BMC Public Health in January analyzed five years of birth cohort data from South Africa. It found striking ties between prenatal exposure to particulate matter and adverse birth outcomes, like low birth weight or preterm birth.
The bodies of pregnant women are simply more vulnerable, meaning international efforts to tackle climate change should factor in their specific needs, said Unity Health Toronto family physician Dr. Samantha Green, from Canadian Association of Physicians for the Environment (CAPE).
“The climate crisis is the biggest health threat we face,” she added, “and it tends to affect people who are already more vulnerable and marginalized the most.”
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Call to action before climate talks
The new paper from the WHO and other United Nations organizations is meant to be a call to action before upcoming international climate talks. The annual Conference of the Parties (COP28) negotiations on climate change is set to start on Nov. 30 in Dubai, and includes the event’s first-ever Day of Health.
The authors wrote that climate change represents a “growing threat to maternal, newborn and child health that can no longer be ignored.” It called for women, children and newborns to be considered priorities in the global climate response, accelerated research, and actions to reduce carbon emissions.
An “over-heating world” is fuelling the spread of deadly diseases like cholera, along with insect-transmitted infections such as malaria and dengue. These infections can have “dire consequences for pregnant women and children,” the WHO noted in a statement.
One modelling study published in the journal Global Change Biology, for instance, projected that more than a billion additional people could live in areas with suitable transmission temperatures for Zika virus by 2050.
That mosquito-spread pathogen led to an outbreak in Brazil in 2015, which spread from pregnant women to their fetuses, leading some children to develop devastating birth defects, including severely underdeveloped brains.
The WHO report also stressed that the impact of climate hazards “may include multiple causes of maternal and neonatal morbidity and mortality such as gestational diabetes, hypertensive disorders of pregnancy, preterm birth, low birth weight and stillbirth.”
Children are also disproportionately impacted, it continued.
Extreme weather can lead to increased rates of depression and stress, mental health issues that could last into adulthood.
Extremely hot or cold temperatures, as well as poor quality air, can damage a child’s respiratory health, boosting risks of impaired lung function, asthma and respiratory infections, the report continued.
“Combined with food insecurity, children are at greater risk of malnutrition as well as increased mortality,” it said.
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Family planning also a solution
Green is glad for the spotlight on specific risks to pregnant women and children but she would have liked the report to touch on another solution to the climate crisis: adequate access to family planning.
“[With] access to family planning and high-quality education for women, we know that we’ll see slower population growth, and that will lead to reduced greenhouse gas emissions,” she said.
Another less-discussed impact of climate on pregnancy, also not discussed in the report, is the health risks associated with evacuations during environmental disasters, Green said.
She cited this summer’s wildfires in the Northwest Territories, which forced the entire city of Yellowknife to evacuate, disrupting the access of pregnant people to essential health services.
In addition to interrupted crucial care, evacuations cause stress for pregnant individuals, said Hodgson, the midwife from B.C. High levels of anxiety while pregnant are also linked to poorer outcomes, including lower birth weights and a higher risk of preeclampsia, a serious high blood pressure disorder that can develop during pregnancy.
“Women’s health, in general, doesn’t get the attention it deserves,” Hodgson said.
“Climate change is a huge issue that absolutely needs to be dealt with, and not just for the health and well-being of the pregnant person and the fetus, but for those babies when they become grown-ups.
“We want them to have a healthy world in which to live.”