Pollution and pregnancy

Various air pollutants affect fertility. For instance, an increase in NO₂ is significantly associated with a lower live birth rate in women undergoing IVF treatment.{{Cite journal |last1=Conforti |first1=Alessandro |last2=Mascia |first2=Marika |last3=Cioffi |first3=Giuseppina |last4=De Angelis |first4=Cristina |last5=Coppola |first5=Giuseppe |last6=De Rosa |first6=Pasquale |last7=Pivonello |first7=Rosario |last8=Alviggi |first8=Carlo |last9=De Placido |first9=Giuseppe |date=2018-12-30 |title=Air pollution and female fertility: a systematic review of literature |journal=Reproductive Biology and Endocrinology |volume=16 |issue=1 |page=117 |doi=10.1186/s12958-018-0433-z |issn=1477-7827 |pmc=6311303 |pmid=30594197 |doi-access=free}} In the general population, there is a significant increase in miscarriage rate in women exposed to NO₂ compared to those not exposed. Similarly, CO exposure is significantly associated with stillbirth in the second and third trimester.

File:Benzo-a-pyrene_chemical_structure.png

Polycyclic aromatic hydrocarbons (PAHs) have been associated with reduced fertility. Benzo(a)pyrene (BaP) is a well-known PAH and carcinogen which is often found in exhaust fumes and cigarette smoke.{{Cite journal |last1=Canipari |first1=Rita |last2=De Santis |first2=Lucia |last3=Cecconi |first3=Sandra |date=January 2020 |title=Female Fertility and Environmental Pollution |journal=International Journal of Environmental Research and Public Health |language=en |volume=17 |issue=23 |page=8802 |doi=10.3390/ijerph17238802 |issn=1660-4601 |pmc=7730072 |pmid=33256215 |doi-access=free}} PAHs have been reported to administer their toxic effects through oxidative stress by increasing the production of Reactive Oxygen Species (ROS) which can result in inflammation and cell death. More long-term exposure to PAHs can result in DNA damage and reduced repair.{{Cite journal |last1=da Silva Junior |first1=Francisco Carlos |last2=Felipe |first2=Maria Beatriz Mesquita Cansanção |last3=Castro |first3=Denis Elvis Farias de |last4=Araújo |first4=Sinara Carla da Silva |last5=Sisenando |first5=Herbert Costa Nóbrega |last6=Batistuzzo de Medeiros |first6=Silvia Regina |date=2021-06-01 |title=A look beyond the priority: A systematic review of the genotoxic, mutagenic, and carcinogenic endpoints of non-priority PAHs |url=https://www.sciencedirect.com/science/article/pii/S0269749121004188 |journal=Environmental Pollution |language=en |volume=278 |page=116838 |bibcode=2021EPoll.27816838D |doi=10.1016/j.envpol.2021.116838 |issn=0269-7491 |pmid=33714059 |s2cid=232222865}}

Exposure to BaP has been reported to reduce sperm motility and increasing the exposure worsens this effect. Research has demonstrated that more BaPs were found in men with reported fertility issues compared to men without.{{Cite journal |last1=Plunk |first1=Elizabeth C. |last2=Richards |first2=Sean M. |date=January 2020 |title=Endocrine-Disrupting Air Pollutants and Their Effects on the Hypothalamus-Pituitary-Gonadal Axis |journal=International Journal of Molecular Sciences |language=en |volume=21 |issue=23 |page=9191 |doi=10.3390/ijms21239191 |issn=1422-0067 |pmc=7731392 |pmid=33276521 |doi-access=free}}

Studies have shown that BaPs can affect folliculogenesis and ovarian development by reducing the number of ovarian germ cells via triggering cell death pathways and inducing inflammation, which can lead to ovarian damage.{{Cite journal |last1=Perono |first1=Genevieve A |last2=Petrik |first2=James J |last3=Thomas |first3=Philippe J |last4=Holloway |first4=Alison C |date=2022-01-01 |title=The effects of polycyclic aromatic compounds (PACs) on mammalian ovarian function |journal=Current Research in Toxicology |language=en |volume=3 |page=100070 |bibcode=2022CRTox...300070P |doi=10.1016/j.crtox.2022.100070 |issn=2666-027X |pmc=9043394 |pmid=35492299}}

A study in California found that increased exposure to PM_2.5 led to decreased sperm motility and increased abnormal morphology. Similarly, in Poland, exposure to PM_2.5 and PM₁₀ led to an increase in the percentage of cells with immature chromatin (DNA that has not fully developed or has developed abnormally).{{Cite journal |last1=Jurewicz |first1=Joanna |last2=Dziewirska |first2=Emila |last3=Radwan |first3=Michał |last4=Hanke |first4=Wojciech |date=2018-12-23 |title=Air pollution from natural and anthropic sources and male fertility |journal=Reproductive Biology and Endocrinology |language=en |volume=16 |issue=1 |page=109 |doi=10.1186/s12958-018-0430-2 |issn=1477-7827 |pmc=6304234 |pmid=30579357 |doi-access=free}}

In Turkey, a study examined the fertility of men who work as toll collectors and are therefore exposed to high levels of traffic pollutants daily. Traffic pollution often has high levels of PM₁₀ alongside carbon monoxide and nitrogen oxides. There were significant differences in sperm count and motility in this study group compared to a control group with limited air pollution exposure.

In women, while overall effects on fertility do not appear significant, there is an association between increased exposure to PM₁₀ and early miscarriage. Exposure to smaller particulate matter, PM_2.5, appears to have an effect on conception rates in women undergoing IVF but does not affect live birth rates.

File:Ozone-structure.png

There is limited research about the effect that ozone pollution has on fertility. At present, there is no evidence to suggest that ozone exposure poses a deleterious effect on spontaneous fertility in either females or males. However, there have been studies which suggest that high levels of ozone pollution, often a problem in the summer months, exert an effect on in vitro fertilisation (IVF) outcomes. Within an IVF population, NO_x and ozone pollutants were linked with reduced rates of live birth.

While most research on this topic is focused on the direct human exposure to air pollution, other studies have analysed the impact of air pollution on gametes and embryos within IVF laboratories. Multiple studies have reported a marked improvement in embryo quality, implantation and pregnancy rates after IVF laboratories have implemented air filters in a concerted effort to reduce levels of air pollution.{{Cite journal |last1=Frutos |first1=Víctor |last2=González-Comadrán |first2=Mireia |last3=Solà |first3=Ivan |last4=Jacquemin |first4=Benedicte |last5=Carreras |first5=Ramón |last6=Checa Vizcaíno |first6=Miguel A. |date=2015-01-02 |title=Impact of air pollution on fertility: a systematic review |journal=Gynecological Endocrinology |volume=31 |issue=1 |pages=7–13 |doi=10.3109/09513590.2014.958992 |issn=0951-3590 |pmid=25212280 |s2cid=41594539}}

In terms of male fertility, ozone is reported to cause a significant decrease in the concentration and count of sperm in semen after exposure.{{Cite journal |last1=Jurewicz |first1=Joanna |last2=Dziewirska |first2=Emila |last3=Radwan |first3=Michał |last4=Hanke |first4=Wojciech |year=2018 |title=Air pollution from natural and anthropic sources and male fertility |url=https://rdcu.be/cWWgF |journal=Reproductive Biology and Endocrinology |language=en |volume=16 |issue=1 |page=109 |doi=10.1186/s12958-018-0430-2 |pmc=6304234 |pmid=30579357 |s2cid=57376088 |access-date=2022-10-05 |doi-access=free}} Similarly, sperm vitality, the proportion of live spermatozoa in a sample, was demonstrated to be diminished as a result of exposure to air pollution.{{Cite journal |last1=Carré |first1=Julie |last2=Gatimel |first2=Nicolas |last3=Moreau |first3=Jessika |last4=Parinaud |first4=Jean |last5=Léandri |first5=Roger |date=2017-07-28 |title=Does air pollution play a role in infertility?: a systematic review |journal=Environmental Health |volume=16 |issue=1 |page=82 |bibcode=2017EnvHe..16...82C |doi=10.1186/s12940-017-0291-8 |issn=1476-069X |pmc=5534122 |pmid=28754128 |doi-access=free}} However, findings on the effect of ozone exposure on male fertility are somewhat discordant.

Areas with high levels of nitrogen dioxide in the air, which is an output of vehicular air pollution, are shown to have negative effects on fetuses. Effects of the exposure include reduced fetal growth, premature birth, and respiratory conditions. Two studies were conducted to evaluate the effects of nitrogen dioxide on fetuses in the southern United States as well as Valencia, Spain. In the United States, babies that were born prematurely were 94% more likely to have been exposed to high levels of pollution than those that were not premature. In Spain, fetuses that were small for gestational age in terms of weight were 37% more likely to have been exposed to high levels of air pollution than those that were not small for gestational age in terms of weight.{{Cite journal |last1=Ballester |first1=Ferran |last2=Estarlich |first2=Marisa |last3=Iñiguez |first3=Carmen |last4=Llop |first4=Sabrina |last5=Ramón |first5=Rosa |last6=Esplugues |first6=Ana |last7=Lacasaña |first7=Marina |last8=Rebagliato |first8=Marisa |date=2010-01-29 |title=Air pollution exposure during pregnancy and reduced birth size: a prospective birth cohort study in Valencia, Spain |journal=Environmental Health |volume=9 |issue=1 |pages=6 |doi=10.1186/1476-069X-9-6 |issn=1476-069X |pmc=2845572 |pmid=20113501 |bibcode=2010EnvHe...9....6B |doi-access=free }}{{Cite journal |last1=Jones |first1=Sara I. |last2=Pruszynski |first2=Jessica E. |last3=Spong |first3=Catherine Y. |last4=Nelson |first4=David B. |date=October 2023 |title=Traffic-related air pollution is associated with spontaneous extremely preterm birth and other adverse perinatal outcomes |url=http://dx.doi.org/10.1016/j.ajog.2023.07.040 |journal=American Journal of Obstetrics and Gynecology |volume=229 |issue=4 |pages=455.e1–455.e7 |doi=10.1016/j.ajog.2023.07.040 |pmid=37516397 |s2cid=260294609 |issn=0002-9378|doi-access=free }}

In Los Angeles County, researchers found a higher risk in premature birth (10-20%) and low birth weight for infants whose mothers lived near high traffic areas Wilhelm, Ritz. (2002). Residential Proximity to Traffic and Adverse Birth Outcomes in Los Angeles County, California, 1994-1996. Environmental Health Perspectives. doi: 10.1289/ehp.5688 Studies conducted on populations living near the 405 and 710 interstates in Southern California found their exposure to particulate vehicle emissions to be almost 25 times higher than for people living 1000 ft from the freeways. This research also concluded that particulate vehicle emissions are more toxic to children's health than other particles, such as Carbon Monoxide and Nitrogen Dioxide Zhu, Hinds, Kim, Sioutas. Concentration and size distribution of ultrafine particles near a major highway. Journal of the Air and Waste Management Association. September 2002. Zhu, Hinds, Kim, Shen, Sioutas. Study of ultrafine particles near a major highway with heavy-duty diesel traffic. Atmospheric Environment. 36(2002), 4323-4335.Marshall JD, Riley WJ, McKone TE, Nazaroff WW: Intake fraction of primary pollutants: motor vehicle emissions in the South Coast Air Basin. Atmos Environ 2003, 37:3455-3468

Carbon monoxide (CO) is directly released from motor vehicles' engines, which are a major source of this pollutant in the LA Basin 5. CO inhaled by pregnant women may threaten the unborn child's growth and mental development. Because CO competes with Oxygen to achieve dispersion throughout the blood stream, fetal hypoxia (lack of oxygen) may result at high levels of maternal CO exposure, however the exact amount of exposure of CO to become a fetal threat is unknown {{cite journal|title=BMC Pregnancy and Childbirth | Article Statistics | |journal=BMC Pregnancy and Childbirth |doi=10.1186/1471-2393-11-101 |publisher=BioMed Central |date= 14 December 2011|volume=11 |issue=1 |page=101 |last1=Venditti |first1=Carolina C. |last2=Casselman |first2=Richard |last3=Smith |first3=Graeme N. |pmid=22168775 |pmc=3297534 |s2cid=2261855 |doi-access=free }} High levels of carbon monoxide are also found in cigarettes, it is advised that pregnant women avoid smoking to not run the risk of affecting their child's growth or mental development. For further information on Carbon Monoxide and its effects on human health, please see Carbon monoxide poisoning.

Nitrogen oxides (NO) are common air pollutants found throughout most of the United States. You can be exposed to these oxides by breathing polluted air, which is most commonly found in areas with heavy motor vehicle traffic {{cite web |url=http://toxtown.nlm.nih.gov/text_version/chemicals.php?id=19 |title=Tox Town - Nitrogen Oxides - Toxic chemicals and environmental health risks where you live and work - Text Version |publisher=National Library of Medicine |date=2013-08-08 |accessdate=2013-11-26 |archive-date=2019-08-02 |archive-url=https://web.archive.org/web/20190802162615/https://toxtown.nlm.nih.gov/text_version/chemicals.php?id=19 |url-status=dead }} Exposure to high levels of Nitrogen oxides damages tissues of the throat and upper respiratory tract and can interfere with the body's ability to carry oxygen. High exposure to nitrogen dioxide may cause fetal mutations, damage a developing fetus, and decrease a woman's ability to become pregnant. Studies have also shown that higher exposures to NO inhibit embryo development during both traditional pregnancies and artificial inseminations {{cite web|url=http://molehr.oxfordjournals.org/content/4/5/503.full.pdf |title=Nitric oxide inhibits development of embryos and implantation in mice |date=1998 |website=molehr.oxfordjournals.org |access-date=2019-07-23}}{{dead link|date=May 2021|bot=medic}}{{cbignore|bot=medic}}{{Cite journal|title=When Blood Meets Nitrogen Oxides: Pregnancy Complications and Air Pollution Exposure|date=April 1, 2013|journal=Environmental Health Perspectives|volume=121|issue=4|pages=a136|doi=10.1289/ehp.121-a136|pmc=3620769|last1=Tillett |first1=Tanya |pmid=23548775 }}

Examples of particulate matter include ash from smoke in campfires, dust particles around your house, and smoke from car exhaust pipes; in areas close to freeways, this is a problem. A study conducted on European women indicated that higher exposure to particulate matter during the initial first weeks of their pregnancy resulted in low birth weight babies Dejmek, J., Selevan, S., Beneš, I., Solanský, I., & Šrám, R. (1999). Fetal growth and maternal exposure to particulate matter during pregnancy. Environmental Health Perspectives, 107(6), 475-480 This toxin is also considered the most dangerous of the three because it can be anything small enough to be inhaled. This may also be because brain growth begins within the first month of conception.

Both household air pollution and ambient air pollution are associated with low birth weight and pre-term delivery. This can lead to fatal outcomes, especially in developing countries.{{cite journal |last1=Ghosh |first1=Rakesh |last2=Causey |first2=Kate |last3=Burkart |first3=Katrin |last4=Wozniak |first4=Sara |last5=Cohen |first5=Aaron |last6=Brauer |first6=Michael |date=28 September 2021 |title=Ambient and household PM2.5 pollution and adverse perinatal outcomes: A meta-regression and analysis of attributable global burden for 204 countries and territories |journal=PLOS Medicine |language=en |volume=18 |issue=9 |pages=e1003718 |doi=10.1371/journal.pmed.1003718 |issn=1549-1676 |pmc=8478226 |pmid=34582444 |doi-access=free}}

A previous study in the Los Angeles Basin of Southern California reported a consistent association between levels of CO and particulate matter during the first trimester and the last six weeks before birth and risk of preterm birth. Prematurity in babies is accompanied by an array of health complications. Children born prematurely are at the highest risk for developing Infant respiratory distress syndrome, gastrointestinal, and hematologic diseases, central nervous system (CNS) problems such as hearing loss, are more prone to infections, and at risk for hearing and vision loss.

Babies born of low weight are also at risk for respiratory, gastrointestinal, cardiac, CNS, infection, and vision problems. These gestational issues persist until the adult years for most children and result in high blood pressure, Type II Diabetes, and other heart diseases.

Prematurity and Low Birth Weight caused by air pollution also affect fetal brain development. This is of importance since lack of proper brain development will not allow a child's brain to form proper synapse connections, which will negatively affect the child's speech, learning abilities, and social skills.

Exposure to air pollution not only affects newborns in early stages of their development, it can also have lifelong consequences for children exposed from the time of conception to when they reach two years of age. Air pollution has been found to cause lower birth weights, insufficient development of the immune system and organs, and premature births. These birth effects have been linked to respiratory issues that can persist into one's long-term health.{{Cite journal |last1=Kioumourtzoglou |first1=Marianthi-Anna |last2=Raz |first2=Raanan |last3=Wilson |first3=Ander |last4=Fluss |first4=Ronen |last5=Nirel |first5=Ronit |last6=Broday |first6=David M. |last7=Yuval |last8=Hacker |first8=Michele R. |last9=McElrath |first9=Thomas F. |last10=Grotto |first10=Itamar |last11=Koutrakis |first11=Petros |last12=Weisskopf |first12=Marc G. |date=January 2019 |title=Traffic-related Air Pollution and Pregnancy Loss |url=http://journals.lww.com/00001648-201901000-00002 |journal=Epidemiology |language=en |volume=30 |issue=1 |pages=4–10 |doi=10.1097/EDE.0000000000000918 |issn=1044-3983 |pmc=6269216 |pmid=30199416}}

Exposure to vehicle air pollutants has been noted as a primary cause for infant mortality and morbidity, and is also argued to be a cause of chronic diseases such as asthma in children and adulthood Dollfus C, Patetta M, Siegel E, Cross AW. Infant mortality: a practical approach to the analysis of the leading causes of death and risk factors. Pediatrics 1990; 86:176–183

The number of children affected by asthma has increased in past decades the point where it is now the most chronic illness in children and the most common cause of children hospitalizations in the U.S. causing it to also be a number one contributor to school absencesGasana, J., Dillikar, D., Mendy, A., Forno, E., & Ramos Vieira, E. (2012). Motor vehicle air pollution and asthma in children: A meta-analysis. Environmental Research, 117, 36-45 Excessive school absences ultimately affect the child's learning ability, and decrease their time to socialize with kids their age. It is not uncommon for children who suffer from asthma to oftentimes repeat grades due to failure to keep up academically. If students are not repeating grades, they are highly likely to drop out before graduation over their non-affected peers.{{Cite journal |last1=Moonie |first1=Sheniz A. |last2=Sterling |first2=David A. |last3=Figgs |first3=Larry |last4=Castro |first4=Mario |date=January 2006 |title=Asthma status and severity affects missed school days |url=https://pubmed.ncbi.nlm.nih.gov/16457681/#:~:text=Excessive%20school%20absence%20disrupts%20learning, the%20causes%20are%20inadequately%20documented. |journal=The Journal of School Health |volume=76 |issue=1 |pages=18–24 |doi=10.1111/j.1746-1561.2006.00062.x |issn=0022-4391 |pmid=16457681}}

Studies have found that children who are exposed to higher levels of car pollutants report higher respiratory problems, including wheezing, ear and throat infections, and have a higher incidence of physician-diagnosed asthma.{{Cite journal |last1=Holst |first1=Gitte J. |last2=Pedersen |first2=Carsten B. |last3=Thygesen |first3=Malene |last4=Brandt |first4=Jørgen |last5=Geels |first5=Camilla |last6=Bønløkke |first6=Jakob H. |last7=Sigsgaard |first7=Torben |date=2020-08-19 |title=Air pollution and family related determinants of asthma onset and persistent wheezing in children: nationwide case-control study |journal=BMJ |language=en |volume=370 |pages=m2791 |doi=10.1136/bmj.m2791 |issn=1756-1833 |pmid=32816747|pmc=7437497 |s2cid=221177828 |doi-access=free }}{{Cite journal |last=Potera |first=Carol |date=September 2006 |title=Heavy Traffic Can Be a Pain in the . . . Ear?: Vehicle Emissions Linked to Otitis Media |journal=Environmental Health Perspectives |volume=114 |issue=9 |pages=A544 |doi=10.1289/ehp.114-a544b |issn=0091-6765 |pmc=1570094}} Bronchiolitis is also found in greater amounts when the child's home is around high amounts of traffic.{{Cite journal |last1=Ruffles |first1=Tom |last2=Inglis |first2=Sarah K. |last3=Memon |first3=Anjum |last4=Seddon |first4=Paul |last5=Basu |first5=Kaninika |last6=Bremner |first6=Stephen A. |last7=Rabe |first7=Heike |last8=Tavendale |first8=Roger |last9=Palmer |first9=Colin N. A. |last10=Mukhopadhyay |first10=Somnath |last11=Fidler |first11=Katy J. |date=2023-09-10 |title=Environmental risk factors for respiratory infection and wheeze in young children: A multicentre birth cohort study |journal=Pediatric Pulmonology |volume=59 |issue=1 |pages=19–30 |language=en |doi=10.1002/ppul.26664 |pmid=37690457 |s2cid=261680649 |issn=8755-6863|doi-access=free }}

Children living close to high traffic areas are also eight times more likely to develop leukemia compared to children who do not.Vinceti, M., Rothman, K., Crespi, C., Sterni, A., Cherubini, A., et al. (2012). Leukemia risk in children exposed to benzene and PM10 from vehicular traffic: A case-control study in an Italian population. European Journal of Epidemiology, 27(10), 781 This finding indicates that children who develop cancer as a result of traffic exposure will also spend more time in the hospital. This is not only a cause of school absences, but also a time of trauma for a child who is constantly visiting providers for treatment. Children with cancer have a harder time keeping up with school and keeping up with their friends Anonymous,. (2012). Awareness week highlights effects of cancer on young children. Cancer Nursing Practice, 11(10), 5

Autism spectrum disorder is a spectrum of disorders that range from severe inability to communicate and some mental disabilities to milder symptoms such as attention disorders. Some claims exist that the incidence of autism is higher for babies whose mothers spend time in ‘high traffic pollution’ areas compared to mothers who spend their pregnancy in cleaner air. In a recent study conducted by UCLA, air pollutant levels were measured for mothers who had children with autism and then compared to air pollutant levels in environments for mothers who had children without autism. This study found that babies who were exposed to higher levels of pollutants while in the womb had a 10% higher risk of autism than babies who had low levels of exposure; another finding from this study is that fine particulates had the strongest association with autism Becerra, T., Wilhelm, M., Olsen, J., Cockburn, M., & Ritz, B. (2013). Ambient air pollution and autism in Los Angeles County, California. Environmental Health Perspectives, 121(3), 380-386

Motor vehicle emissions are not solely a United States issue. Of the 10 cities with the most traffic, there are no cities from the United States listed.{{Cite web |date=2023-09-05 |title=10 Cities with the Worst Traffic in the World - Ranked 2023 |url=https://www.geeksforgeeks.org/cities-with-worst-traffic-in-the-world/ |access-date=2023-11-20 |website=GeeksforGeeks |language=en-US}} The United States also has regulations regarding what and how many emissions vehicles are allowed to emit that are on the road. This is done by the USEPA and they are currently working on new regulations.{{Cite web |last=USEPA |title=Regulations for Greenhouse Gas Emissions from Passenger Cars and Trucks |url=https://www.epa.gov/regulations-emissions-vehicles-and-engines/regulations-greenhouse-gas-emissions-passenger-cars-and }} Of the countries that have vehicle emission standards, the European Union and Japan have the most strict regulations. These standards have been added because it is shown that regulating fuel economy is effective in controlling oil demands for the country as well as reducing its greenhouse emissions.{{Cite web |title=Comparison of Passenger Vehicle Fuel Economy and GHG Emission Standards Around the World |url=https://www.c2es.org/document/comparison-of-passenger-vehicle-fuel-economy-and-ghg-emission-standards-around-the-world/ |access-date=2023-11-20 |website=Center for Climate and Energy Solutions}}

Respiratory and allergic disorders among children in Japan were studied after the implementation of new regulations were put in place and it showed the prevalence of asthma and other respiratory disorders decreased.{{Cite journal |last1=Hasunuma |first1=Hideki |last2=Ishimaru |first2=Yasushi |last3=Yoda |first3=Yoshiko |last4=Shima |first4=Masayuki |date=May 2014 |title=Decline of ambient air pollution levels due to measures to control automobile emissions and effects on the prevalence of respiratory and allergic disorders among children in Japan |url=https://pubmed.ncbi.nlm.nih.gov/24727639/ |journal=Environmental Research |volume=131 |pages=111–118 |doi=10.1016/j.envres.2014.03.007 |issn=1096-0953 |pmid=24727639|bibcode=2014ER....131..111H }} There have also been more recent studies showing that the incidence of asthma cases worldwide is increasing in children. Much of this increase is due to the increase in NO2 which is a gas that is emitted from motor vehicles among other sources.{{Cite web |title=Nearly 2 Million Children Worldwide Develop Asthma as a Result of Breathing in Traffic- Related Pollution {{!}} Milken Institute School of Public Health {{!}} The George Washington University |url=https://publichealth.gwu.edu/nearly-2-million-children-worldwide-develop-asthma-result-breathing-traffic-related-pollution |access-date=2023-11-20 |website=Milken Institute School of Public Health |language=en}}

Across the United States, vehicle emissions make up a large portion of air pollution, especially in urban areas. An epidemiological study conducted by the National Institute of Health compared pregnancy loss to local vehicle emissions, specifically nitrogen dioxide (NO₂). The study used data from Boston, Massachusetts, and Tel Aviv, Israel, and both regions observed associations between pregnancy loss and NO₂, largely in the second trimester of pregnancies. This study further increases scientific confidence that vehicle emissions can be detrimental to pregnant individuals and fetuses and that these findings are consistent in different geographic locations and among different populations.{{Cite journal |last1=Rani |first1=Prerna |last2=Dhok |first2=Archana |date=2023-01-18 |title=Effects of Pollution on Pregnancy and Infants |journal=Cureus |volume=15 |issue=1 |pages=e33906 |language=en |doi=10.7759/cureus.33906 |doi-access=free |issn=2168-8184 |pmc=9937639 |pmid=36819435}}

• Environmental impact of transport
• List of most-polluted cities by particulate matter concentration

{{Reflist}}

• [http://www.zerotothree.org/child-development/brain-development/ Zero To Three] - information on child brain development

{{Pregnancy}}

Category:Air pollution in the United States

Category:Smog

Category:Transport and the environment

Category:Health and transport

Category:Human pregnancy