Thesis defence in the University of Oulu

Doctoral Candidate

M.Sc (Public Health) Nazeeba Siddika

Faculty and research unit

University of Oulu Graduate School, Faculty of Medicine, The Center for Environmental and Respiratory Health Research (CERH)
+358 40 672 0927

Field of study

Public Health Sciences

Date and time of the thesis defence

6.11.2020 12:00

Place of the thesis defence

Auditorium F202 of the Faculty of Medicine (Aapistie 5 B), Zoom link: https://oulu.zoom.us/j/63559175172

Topic of the dissertation

Prenatal exposure to ambient air pollution and the risk of preterm birth and stillbirth. Synergy among air pollutants in causing preterm birth

Opponent

Docent Otto Hänninen, Finnish Institute for Health and Welfare (THL)

Custos

Professor Jouni J. K. Jaakkola, University of Oulu

Prenatal exposure to ambient air pollution and the risk of preterm birth and stillbirth. Synergy among air pollutants in causing preterm birth

Previous epidemiologic studies have shown little evidence that exposure to low-level air pollution during pregnancy may increase the risk of preterm birth (PTB). None of the previous studies had elaborated the joint effects of different air pollutants or the synergistic effects of different air pollutants on the risk of PTB. The evidence from previous studies on the effects of air pollution exposure during pregnancy and the risk of stillbirth is not clear.

This project assessed the independent and joint effects of prenatal exposure to ambient air pollution on the risk of PTB, and summarized the existing evidence on the relationship between ambient air pollution and the risk of stillbirth through a systematic review and meta-analysis. The study population comprised 2,568 members of the Espoo Cohort Study, born between 1984 and 1990, living in Espoo, Finland.

This thesis project has produced novel findings that simultaneous exposure to ambient air pollutant PM2.5 and O3 during entire duration of pregnancy (Long-term exposure) may potentiate each other’s adverse effect synergistically i.e., more than summation of their individual effects in causing preterm birth. However, exposure during the week prior to the delivery (short-term exposure) to different air pollutants did not show such increasing synergistic effects on the risk of preterm birth.

The results of this study strengthen the evidence that prenatal exposure may cause preterm birth even among people living in an area with relatively low average concentrations of air pollution. In addition, the systematic review and meta-analysis results provide suggestive evidence that ambient air pollution is a risk factor for stillbirth.

In order to prevent air pollution-induced adverse pregnancy outcomes such as PTB and stillbirth, among future infants, this study suggests for (a) designing effective public health preventive strategies, which could be targeted especially on vulnerable populations such as pregnant women, and for (b) promoting policies aimed at reducing air pollution levels and setting standards for combinations of air pollutants, as well as for setting standards for emission sources at the same time.

Dissertation

Last updated: 26.10.2020