The effect of nitrogen dioxide on low birth weight in women with inflammatory bowel disease: a Norwegian pregnancy cohort study (MoBa)

Abstract

Background: Adverse birth outcomes are more frequent among mothers with inflammatory bowel diseases (IBDs) than non-IBD mothers. In recent studies, air pollution, such as high concentrations of nitrogen dioxide (NO₂), is reckoned as a risk factor for preterm birth in the general population. In this study, we investigated whether IBD mothers are at higher risk of preterm birth when exposed to NO₂ compared to non-IBD mothers.

Methods: We used information from the Norwegian Mother, Father and Child Cohort Study (MoBa). The pregnancy cohort was linked to the Norwegian Medical Birth Registry and air-pollution exposure data available from a subset of the study cohort. The relevant outcome in this study was preterm birth. A total of 16,170 non-IBD and 92 IBD mothers were included in the study.

Results: The mean exposure of NO₂ during the pregnancy was similar for IBD and non-IBD mothers, 13.7 (6.9) μg/m³ and 13.6 (4.2) μg/m³, respectively.

IBD mothers with higher exposure of NO₂ in the second and third trimester were at significant risk of preterm birth compared to non-IBD mothers [OR = 1.28 (CI 95%: 1.04–1.59) and OR = 1.23 (95% CI: 1.06–1.43), respectively]. The mean NO₂ exposure was significantly higher in IBD mothers with preterm birth than in IBD mothers who delivered at term, at 19.58 (1.57) μg/m³ and 12.89 (6.37) μg/m³, respectively.

Conclusions: NO₂ exposure influenced the risk of preterm birth in IBD mothers. Higher risk of preterm birth in IBD was associated with higher exposure of NO₂, suggesting vulnerability of preterm birth in IBD when exposed to NO₂.

Keywords:

• The Norwegian Mother
• Father and Child Cohort Study
• air pollution
• inflammatory bowel disease
• pregnancy outcomes

Acknowledgements

We are grateful to all the families in Norway who took part in this ongoing cohort study.

Consent for publication

The participants have given consent for the publication of the data from the MoBa study.

Author contributions

The concept and design was worked out by GAA, BFG, MHV, CM, and MBB. Analyses and interpretation of data were performed by GAA. BFG wrote the paper. All authors contributed to drafting and editing the manuscript. All authors have read and approved the manuscript for publication.

Disclosure statement

Morten H. Vatn: Advisory board, Genetic Analysis. The authors listed below do not have any financial or other relationshiip(s) to disclose: Bjørnar Finnanger Garshol, May-Bente Bengtson, Geir Aamodt, Christian Madsen.

Data availability

The consent given by the participants does not open for storage of data on an individual level in repositories or journals. Researchers who want access to data sets for replication should submit an application to [email protected]. Access to data sets requires approval from the Regional committees for medical and health research ethics in Norway and a formal contract with MoBa.

Additional information

Funding

The Norwegian Mother and Child Cohort Study is supported by the Norwegian Ministry of Health and Care Services and the Ministry of Education and Research, NIH/NIEHS [grant number N01-ES-75558]; NIH/NINDS [grant number 1 UO1 NS 047537-01], [grant numberUO1 NS 047537-06A1]; and South-Eastern Norway Regional Health Authority.

The Norwegian Mother and Child Cohort Study is supported by the Norwegian Ministry of Health and Care Services and the Ministry of Education and Research, NIH/NIEHS [contract number N01-ES-75558]; NIH/NINDS [grant no.1 UO1 NS 047537-01 and grant no.2 UO1 NS 047537-06A1]; and South-Eastern Norway Regional Health Authority.