Breathing dirty air may raise miscarriage risk

November 16, 2017 by Dennis Thompson, Healthday Reporter

(HealthDay)—Smog might raise a woman's risk of miscarriage early in her pregnancy, a new study suggests.

Chronic seemed to increase that risk by more than 10 percent, according to researchers who tracked hundreds of pregnancies among couples in Michigan and Texas.

"We found that both ozone and particles in the air were related to an increased risk of early pregnancy loss," said senior researcher Pauline Mendola. She is an investigator with the U.S. National Institute of Child Health and Human Development.

Mendola and her team reviewed data from a long-term study from the U.S. National Institutes of Health that followed 501 couples between 2005 and 2009.

There were 343 couples who achieved pregnancy, but 98 (28 percent) lost the pregnancy within the first 18 weeks, the investigators said.

The team estimated the couples' exposure to smog based on pollution levels detected in their residential communities, and then looked to see if the bad air may have had any effect on pregnancy.

The findings showed that exposure to ozone appeared to increase risk of pregnancy loss by 12 percent, and exposure to fine airborne particles raised it by 13 percent. That was even after the researchers compensated for other factors that can affect the of a pregnancy, such as age, race, education, income, weight, fertility, and caffeine and multivitamin intake.

The researchers estimated that nine of the 98 lost pregnancies could have been saved had the expectant mother been exposed to lower levels of smog or none at all.

No one knows exactly why smog exposure is associated with , Mendola said. And the study did not prove that smog exposure caused miscarriages, just that there was an association.

Inflammation and oxidative stress prompted by air pollution could jeopardize a pregnancy in a number of possible ways, Mendola said. It could harm fetal development, interfere with implantation of the fertilized egg in the uterus, or cause problems with development of the placenta.

"We don't know because we can't measure that with these data," Mendola explained. "All we can say is we see an association between air pollution exposures in pregnancy and the risk of loss."

One women's health expert offered another theory.

There's a possibility that toxins in air pollution might cross the placenta and directly harm the fetus, said Dr. Jill Rabin, co-chief of ambulatory care with Women's Health Programs-PCAP Services at Northwell Health in New Hyde Park, N.Y.

"It's incomprehensible that something you're breathing in that's toxic wouldn't affect young developing tissue," Rabin said. "It's conceivable some of those toxins would be able to get through the placenta and to the baby."

Mendola said she wants to test this finding in larger groups of people, and also explore more deeply the biological ways air pollution could harm a pregnancy.

In the meantime, pregnant women should try to limit their exposure to heavy smog, she advised.

"When you have air-quality alerts, we would say it's probably prudent to suggest that pregnant women adapt their behavior," Mendola said. "Avoid outdoor activities, the same as people with asthma or respiratory disease would."

One pulmonologist agreed.

"The results of the study are not surprising since air pollution has been shown to be associated with multiple health issues in adults including, but not limited to, pulmonary [lung] and cardiac conditions," said Dr. Alan Mensch. He's senior vice president of medical affairs at Syosset Hospital, in Syosset, N.Y.

"Avoidance of air , especially during those days when there are alerts, is obviously also an important factor for preserving a viable ," he added.

The study was published Nov. 16 in the journal Fertility and Sterility.

Explore further: Air pollution linked to higher risk of preterm birth for mothers with asthma

More information: Pauline Mendola, Ph.D., investigator, U.S. National Institute of Child Health and Human Development; Jill Rabin, M.D., co-chief, ambulatory care, Women's Health Programs-PCAP Services, Northwell Health, New Hyde Park, N.Y.; Alan Mensch, M.D., senior vice president, medical affairs, Plainview and Syosset hospitals, Long Island, N.Y.; Nov. 16, 2017, Fertility and Sterility

For more on the health effects of smog, visit the Environmental Protection Agency.

Related Stories

Air pollution linked to higher risk of preterm birth for mothers with asthma

March 1, 2016
Pregnant women with asthma may be at greater risk of preterm birth when exposed to high levels of certain traffic-related air pollutants, according to a study by researchers at the National Institutes of Health and other ...

Study will explore air pollution's impact on the developing fetus

October 10, 2017
New research will seek to understand the biological mechanisms that are triggered by exposure to air pollution during pregnancy and lead to lower birth weight in newborns, placing them at greater risk for chronic conditions ...

Negative birth outcomes linked to air pollution exposure early in pregnancy, study finds

July 27, 2017
Exposure to air pollution early in a pregnancy could increase risk for preterm birth and low birth weight, according to a study led by researchers at NYU School of Medicine, and published on July 27 in Environmental Health ...

Extreme temperatures may increase risk for low birth weight at term, study suggests

February 28, 2017
Extreme hot or cold temperatures during pregnancy may increase the risk that infants born at term will be of low birth weight, according to a study of U.S. women by researchers at the National Institutes of Health. The study ...

Researchers find more preterm births among women exposed to extremes of hot and cold

September 1, 2016
Extreme hot or cold temperatures during pregnancy may increase the risk of preterm birth, according to study by researchers at the National Institutes of Health.

Weight gain between pregnancies linked to increased risk of gestational diabetes

August 1, 2017
The risk of developing gestational diabetes mellitus (GDM) increases with increased weight gain between pregnancies, according to a new study published in PLOS Medicine by Linn Sorbye of the University of Bergen, Norway, ...

Recommended for you

New technology can keep an eye on babies' movements in the womb

July 19, 2018
A new system for monitoring fetal movements in the womb, developed by Imperial researchers, could make keeping an eye on high-risk pregnancies easier.

Why baby's sex may influence risk of pregnancy-related complicatations

July 12, 2018
The sex of a baby controls the level of small molecules known as metabolites in the pregnant mother's blood, which may explain why risks of some diseases in pregnancy vary depending whether the mother is carrying a boy or ...

Study analyzes opioid overdose risk during and after pregnancy among Massachusetts women

July 11, 2018
A study of women giving birth in Massachusetts found a higher level of opioid use disorder than have studies conducted in other states. In a paper published in the journal Obstetrics & Gynecology, the research team—consisting ...

High blood pressure in pregnancy linked to mother's heart function

July 9, 2018
Pregnant women who develop high blood pressure, or have small babies, may have hearts that pump less blood with each beat.

What you eat while pregnant may affect your baby's gut

July 4, 2018
A mother's diet during pregnancy may have an effect on the composition of her baby's gut microbiome—the community of bacteria living in the gut—and the effect may vary by delivery mode, according to study published in ...

New study reveals time and day women are most likely to give birth

June 15, 2018
A new study has found that the time and day that women give birth can vary significantly depending on how labour starts and the mode of giving birth.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.