Long-Term Exposure to Heat and Cold Affects Newborn Lung Function

Long-term exposure to extreme temperatures from the second trimester to 4 weeks post-delivery may impact lung function among female newborns, according to a study published in the JAMA network.

Dr. Johanna Lepeule and colleagues at a French university conducted a study to determine if maternal and newborn exposures to heat and cold were associated with newborn lung function.

The researchers recruited pregnant women in France between July 8, 2014, and July 24, 2017. There were 343 mother-child pairs included in the analysis. The median maternal age at conception was 32, and more than half (53%) of newborns were male. The researchers reviewed the data on temperature exposure and lung function in the mother-child pairs. Data analysis was performed from January 1, 2021, to December 31, 2021.

The researchers observed that newborns exposed to heat for a long time had lower lung capacity and increased respiratory rate than those not exposed to heat.

The researchers found that among the female newborns, long-term heat exposure (24°C, or 75°F) during the second and third trimesters of pregnancy and within the first month after delivery was associated with decreased functional residual capacity (FRC) (-39.7 mL, 95% CI -68.6 to -10.7) compared with those exposed to median temperatures (12°C, or 54°F). Long-term exposure to heat also increased respiratory rate during gestational weeks 14-35 and the first week of life (28.0/min, 95% CI 4.2-51.9).

In addition, the researchers found that long-term exposure to cold during the second or third trimester and 0-4 weeks after delivery was associated with a decreased tidal volume of 23.8 mL (95% CI, -43.1 to -4.4 mL), a decreased FRC of 21.9 mL (95% CI, -42.4 to -1.3 mL), and an increased respiratory rate of 45.5 breaths per minute (95% CI, 10.1 to 81.0) compared to the median temperature.

“Decreased forced vital capacity and peak expiratory flow have been associated with short-term and long-term exposure to extreme temperatures in healthy children or children with asthma,” stated the researchers. “During pregnancy, high diurnal temperature variations have been associated with significant increase of pneumonia diagnosis and the common cold in children,” they added.

Surprisingly, the researchers found no consistent association between male newborns or short-term exposure to cold or heat.

In addition, the researchers wrote that direct temperature exposure after birth may alter both the respiratory system and lung function, and these physiologic alterations may affect lung development of the fetus.

“Research must continue to better understand the long-term impact of unusual temperatures in early life and to raise awareness of health risks posed by heat and cold exposure during this period among pregnant women, mothers, and healthcare professionals,” the authors concluded.

Source: Medpage Today

Journal Source: JAMA network