Risk of miscarriage in women with chronic diseases in Norway: A registry linkage study

Maria C Magnus*, Nils-Halvdan Morken, Knut-Arne Wensaas, Allen J Wilcox, Siri E Håberg

*Corresponding author for this work

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Abstract

BACKGROUND: Increased risk of miscarriage has been reported for women with specific chronic health conditions. A broader investigation of chronic diseases and miscarriage risk may uncover patterns across categories of illness. The objective of this study was to study the risk of miscarriage according to various preexisting chronic diseases.

METHODS AND FINDINGS: We conducted a registry-based study. Registered pregnancies (n = 593,009) in Norway between 2010 and 2016 were identified through 3 national health registries (birth register, general practitioner data, and patient registries). Six broad categories of illness were identified, comprising 25 chronic diseases defined by diagnostic codes used in general practitioner and patient registries. We required that the diseases were diagnosed before the pregnancy of interest. Miscarriage risk according to underlying chronic diseases was estimated as odds ratios (ORs) using generalized estimating equations adjusting for woman's age. The mean age of women at the start of pregnancy was 29.7 years (SD 5.6 years). We observed an increased risk of miscarriage among women with cardiometabolic diseases (OR 1.25, 95% CI 1.20 to 1.31; p-value <0.001). Within this category, risks were elevated for all conditions: atherosclerosis (2.22; 1.42 to 3.49; p-value <0.001), hypertensive disorders (1.19; 1.13 to 1.26; p-value <0.001), and type 2 diabetes (1.38; 1.26 to 1.51; p-value <0.001). Among other categories of disease, risks were elevated for hypoparathyroidism (2.58; 1.35 to 4.92; p-value 0.004), Cushing syndrome (1.97; 1.06 to 3.65; p-value 0.03), Crohn's disease (OR 1.31; 95% CI: 1.18 to 1.45; p-value 0.001), and endometriosis (1.22; 1.15 to 1.29; p-value <0.001). Findings were largely unchanged after mutual adjustment. Limitations of this study include our inability to adjust for measures of socioeconomic position or lifestyle characteristics, in addition to the rareness of some of the conditions providing limited power.

CONCLUSIONS: In this registry study, we found that, although risk of miscarriage was largely unaffected by maternal chronic diseases, risk of miscarriage was associated with conditions related to cardiometabolic health. This finding is consistent with emerging evidence linking cardiovascular risk factors to pregnancy complications.

Original languageEnglish
Article numbere1003603
Pages (from-to)e1003603
Number of pages15
JournalPLoS Medicine
Volume18
Issue number5
Early online date10 May 2021
DOIs
Publication statusE-pub ahead of print - 10 May 2021

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Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

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