Understanding how heat waves can affect pregnant women: ‘Climate change is only increasing their vulnerability’

Across the world, many countries — some of them for the first time — are experiencing extreme temperatures, drought, famines, and increased precipitation, owing to climate change. In fact, according to The Lancet, “climate change is the biggest threat to global public health in the 21st century” with its July 2021 report noting that more than five million people died on average each year worldwide because of extreme temperatures in a span of two decades (2000-2019). From an increase in death and illness due to severe weather to worsening air quality, changing patterns of infection, and disruption to food supplies, the “health effects of climate change are far-reaching”, it noted. Furthermore, this year, the month of February was the hottest so far in India since 1901, according to the Indian Meteorological Department.

As such, while it has been proven that extreme climatic conditions can be detrimental to health, how do these — especially heatwaves — impact pregnant women in developing countries like India?

“Most women do a lot of physical labour until almost the last few days of pregnancy. Climate change is only increasing their vulnerability to spontaneous abortions, premature labour and low birth weight, leading to increased neonatal morbidity and mortality,” said Dr Namita Kapoor Sahgal, senior consultant, obstetrics and gynaecology, Manipal Hospital, Varthur, Bangalore.

She added that extreme temperatures and precipitation expose expecting mothers to dehydration, and vector-borne diseases like malaria and dengue which are endemic in India, “with diarrhoea leading to dehydration, exhaustion, fetal malnutrition, and worm infestation, which may further lead to anaemia”. She further cited a 2021 review published in the Journal of Global Health Science, which found that climate change is likely to increase the incidence of vector-borne diseases such as Zika virus, dengue fever, and malaria, and said that these “can be particularly harmful to pregnant women and fetuses.”

According to a 2018 study from National Center for Biotechnology Information, India has the highest burden of climate-sensitive diseases in the world, with maternal and child health being one of the most affected.

“Some studies have also found that for every 1°C increase in temperature, the risk of gestational diabetes increases by approximately six per cent,” said Dr Radha Rao, senior consultant obstetrician and gynaecologist, Apollo Cradle and Children’s Hospital, Jayanagar, Bangalore. Noting that pregnant women are already at a slightly higher risk of “overheating due to hormonal changes that affect their body’s ability to regulate temperature,” Dr Rao told indianexpress.com that “when the mother’s body temperature rises above 102.2°F (39°C), it can increase the risk of neural tube defects, preterm labour, and miscarriage.”

Dr Sahgal listed a few commonly seen issues due to heatwaves

Lowered amniotic fluid: Dehydration can lead to lowered amniotic fluid, in which the baby floats. Amniotic fluid is the protective cushion that helps the fetus against physical impact and also temperature changes. It also gives freedom of movement to the baby to help it grow and develop properly.

Urinary tract infections: Dehydration can also lead to urinary concentration causing such infections frequently.

Fatigue: Severe dehydration due to high-temperature exposure can lead to low blood pressure leading to fatigue and at times, fainting and dizziness.

Preterm labour: High temperatures can lead to the release of anti-diuretic hormones and oxytocin to help retain water. Released oxytocin can trigger premature contractions leading to preterm labour.

Reduced fetal growth: High temperatures reduces the blood flow to the uterus and hence to the foetus. This leads to reduced oxygenation and nutrition to the baby, which in turn can lead to suboptimal growth of the foetus or which is known as intrauterine growth retardation.

Increased possibility of preeclampsia: High-temperature exposure can cause inflammation and oxidative stress in the body, and this can contribute to high blood pressure conditions called preeclampsia amongst women who are already prone to hypertension.

Increased birth defects: High-temperature exposure, especially in the first trimester, can lead to birth defects like neural tube defects and congenital heart defects.

Dr Surabhi Siddhartha, consultant obstetrician and gynaecologist, Motherhood Hospital, Kharghar agreed and said that various problems in newborns — like fetal distress, reliance on a ventilator, and meconium aspiration — are commonly seen due to exposure to higher temperatures. In mothers, pregnancy-related hypertension, uterine bleeding during pregnancy, and an incompetent cervix can be bothersome and may require immediate medical attention. “Climate change can make one tired and drained. A pregnant woman may struggle to do her daily chores with ease,” said Dr Siddhartha.

Dr Sowmya Raghavan, consultant obstetrician and gynaecology, Apollo Cradle Children’s Hospital, Karapakkam Chennai also said that maternal hyperthermia increases the odds of neonatal brain injuries, such as cerebral palsy, due to the amount of oxygen and substrates delivered to the brain being insufficient to meet the increased demand during extreme temperatures. “This leads to neurological sequelae in children. Low-birth-weight babies are more prone to neonatal infections, and NICU stays,” said Raghavan.

As the summer is getting hotter, experts said it is important to see if there’ll be any such cases in the upcoming months, which can be studied further to make solid conclusions about the impact of heat waves and climate change on pregnancy outcomes. “We need to take urgent action concerning climate change, not only for expecting mothers now but also the future generation that they are carrying,” said Dr Sahgal.

Preventive steps

To prevent heatstroke, pregnant women should avoid overheating, wear loose and comfortable clothing, stay hydrated, and avoid being outside during the hottest parts of the day, said Dr Rao. It is also recommended they take frequent breaks in a shaded place, and seek out air-conditioned spaces if possible. If heatstroke is suspected, it is important to seek immediate medical attention.

Dr Siddhartha too said that one should eat hydrating foods such as muskmelon, watermelon, apples, peaches, cucumbers, and celery. Try to avoid junk, spicy, oily, canned, and processed foods. Use sunscreen, and exercise indoors,” added Dr Siddhartha.

Additionally, minor modifications in labour wards such as heat proofing, white reflective paint for rooftops, and if possible air conditioning, and greening the surrounding open spaces can help, said Dr Raghavan.