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Air pollution causes thyroid problems in newborns

Executive Summary

Air pollution has become a serious problem in many countries. If a pregnant woman is exposed to polluted air during her pregnancy, the pollutants can enter the system of her fetus. Such newborns are vulnerable since their immune system is not fully developed.

Air pollution is found to alter thyroid hormones in newborns. Since thyroid hormones are strongly linked to the growth of the babies, air pollution affects their development badly.

It is not clear which trimester of the pregnancy is more vulnerable to air pollution. So pregnant women should avoid air pollution, indoors as well as outdoors, all through the pregnancy.

The article explains the problems small babies face because of maternal exposure to air pollution.

Every day, we are hearing a new medical problem that has arisen due to air pollution.

While we had air pollution for a good part of the last century, the intensity of the problem has increased significantly in the last two decades. There are various reasons for the same, including the increased vehicular density, higher population concentration in the cities, etc.

The most vulnerable lives are those of the little children, especially the newborns. If a pregnant woman is exposed to polluted air during pregnancy, some pollutant particles can enter her bloodstream, from where they can travel to the womb, the placenta, and then finally into the system of the newborn.

Thyroid problems in children


Hypothyroidism, or underactive thyroid, in very young children, can cause:

  • Slow bone growth
  • Intellectual disability
  • Serious developmental delays
  • Jaundice
  • Poor appetite
  • Umbilical hernia (navel protrudes out)


Hyperthyroidism, or overactive thyroid, can cause the following problems in very young children:

  • Small or abnormally shaped head
  • Intellectual disability
  • Hyperactivity
  • Slowed growth
  • Low birth weight
  • Poor weight gain, despite adequate caloric intake
  • Enlarged liver and spleen
  • Goiter
  • Difficulty breathing due to the enlarged thyroid gland (goiter) pressing on the windpipe
  • Bulging eyes
  • Fast heartbeat (which can lead to heart failure)
  • High blood pressure
  • Nervousness, irritability, and difficulty sleeping

Pollution and thyroid problems

Studies have shown that tobacco smoke affects adult as well as fetal thyroid function. So, pregnant women are strongly advised to stay away from smoking, as well as secondary tobacco smoke.

A March 2017 study published in the journal Clinical Thyroidology showed that exposure to air pollution decreases cord Free T4 and increases cord Free T3 levels. Lower cord Free T4 levels are associated with lower birth weight.

A new research paper published in the journal JAMA Network Open showed that if a pregnant woman is exposed to high PM2.5 pollution during certain stages of pregnancy, the newborn baby may end up with higher levels of total Thyroxine (T4).

The Clinical Thyroidology study observed an inverse association between PM2.5 and free T4, while in contrast PM2.5 was positively associated with total T4 in the JAMA Network Open study.

But, don’t go by the exact direction of change in T4. The majority of T4 is bound to serum transport proteins, such as thyroxin–binding globulin (TBG). So free T4 makes up only a small percentage (0.02%) of total T4. Hence, these findings may not be inconsistent.

What is more important to note is that air pollution affects thyroid levels. Since thyroid hormones are strongly linked to growth, development, and other parameters, their levels are very tightly controlled in the body. If their levels go too high or too low, not only is it bad for the body, but it also suggests that the body is not able to regulate them, pointing to a major problem.

In conclusion

Pregnant women should take extra care to avoid air pollution, which can be outdoors as well as indoors.

Since science still does not know which trimester of the pregnancy is more vulnerable to air pollution, it is best to stay protected all through the pregnancy.

First published on: 15th September 2018


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