• Maria C Magnus, Allen J Wilcox, Nils-Halvdan Morken, Clarice R Weinberg, and Siri E Håberg.
• Centre for Fertility and Health, Norwegian Institute of Public Health, PO Box 222 Skøyen, N-0213 Oslo, Norway.
• BMJ. 2019 Mar 20; 364: l869.

ObjectivesTo estimate the burden of miscarriage in the Norwegian population and to evaluate the associations with maternal age and pregnancy history.DesignProspective register based study.SettingMedical Birth Register of Norway, the Norwegian Patient Register, and the induced abortion register.ParticipantsAll Norwegian women that were pregnant between 2009-13.Main Outcome MeasureRisk of miscarriage according to the woman's age and pregnancy history estimated by logistic regression.ResultsThere were 421 201 pregnancies during the study period. The risk of miscarriage was lowest in women aged 25-29 (10%), and rose rapidly after age 30, reaching 53% in women aged 45 and over. There was a strong recurrence risk of miscarriage, with age adjusted odds ratios of 1.54 (95% confidence interval 1.48 to 1.60) after one miscarriage, 2.21 (2.03 to 2.41) after two, and 3.97 (3.29 to 4.78) after three consecutive miscarriages. The risk of miscarriage was modestly increased if the previous birth ended in a preterm delivery (adjusted odds ratio 1.22, 95% confidence interval 1.12 to 1.29), stillbirth (1.30, 1.11 to 1.53), caesarean section (1.16, 1.12 to 1.21), or if the woman had gestational diabetes in the previous pregnancy (1.19, 1.05 to 1.36). The risk of miscarriage was slightly higher in women who themselves had been small for gestational age (1.08, 1.04 to 1.13).ConclusionsThe risk of miscarriage varies greatly with maternal age, shows a strong pattern of recurrence, and is also increased after some adverse pregnancy outcomes. Miscarriage and other pregnancy complications might share underlying causes, which could be biological conditions or unmeasured common risk factors.Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

30 keywords...

hide…