asthma and pregnancy complicationsPreeclampsia is a pregnancy complication that can lead to hypertension, protein in urine and preterm delivery. The only cure for the condition is delivery of the fetus. Researchers have been looking for a definitive cause of preeclampsia for years. One such study, recently published in the journal BMJ Open, reveals that one in 20 cases of preeclampsia may be linked to air pollution and not any physical cause within the body; though moms suffering from asthma may be more apt to suffer preeclampsia associated with air pollution.

Researchers used data collected between 1998 and 2006 in Stockholm. In all, more than 120,000 births were investigated. Asthma diagnosis among mothers and air quality for the time when pregnancy occurred were noted. Preterm delivery occurred in 4.4% of pregnancies. Preeclampsia was associated with 2.7% of births.

Vehicle exhaust did not increase pregnancy complications and air pollution showed no impact on weight at birth, but researchers did find a connection between air pollution and ozone and preeclampsia and preterm delivery. Exposure occurred during the first three months of gestation, the most critical time in fetal development.

Risk increased by 4% for every 10 ug/m3 rise in ozone. Maternal asthma increased risk of preeclampsia and preterm delivery dramatically. Pregnant women with asthma were showed a 25% increase in risk of preterm delivery and 10% increase in risk of preeclampsia.

Researchers narrowed the results by taking contributing factors into consideration, including maternal age, education, season at time of pregnancy, year of birth and ethnicity. Overall, about one in 20 cases of preeclampsia were associated with ozone or air pollution contact during the first three months of pregnancy. Researchers did not offer any insight into further study plans or possible changes in maternal care for women with asthma or women living in areas of high air pollution or ozone levels.

Source: D. Olsson, I. Mogren, B. Forsberg. Air pollution exposure in early pregnancy and adverse pregnancy outcomes: a register-based cohort study. BMJ Open, 2013; 3 (2): e001955 DOI: 10.1136/bmjopen-2012-001955.