Pre-eclampsia is signified when the blood pressure rises and there is protein in the urine, during pregnancy. If this is left untreated, it can cause major problems and complications during the birth. The trial was based on the results of 121,000 births in Sweden during 1998 and 2006 – the prevalence of asthma in the mothers and the levels of air pollutants were included in the study.
Scientists discovered that there are a growing number of cases where evidence proves that air pollution and premature births are linked. In addition to this, they state that those with asthma are also more likely to have complications during pregnancy, such as underweight babies and pre-eclampsia.
The study found no link between levels of vehicle exhaust fumes and complications in pregnancies, nor those between air pollutants and underweight babies. However, the exposure to ozone levels in the first three months of pregnancy did show an increased risk of premature birth and pre-eclampsia.
Asthma, an inflammatory disease, worsens respiratory symptoms and inflammation of the system, so this could account for the increased risk of premature birth amongst those with asthma. Mothers with asthma have a 25% higher chance of their baby being born prematurely, and a 10% chance of having pre-eclampsia. The researchers took into account the age, number of previous births, ethnicity, season and year of conception, with the results showing that one in every twenty cases of pre-eclampsia showing links to the ozone levels in the early stages of pregnancy.