title: Prevalence of maternal chronic diseases during pregnancy - a nationwide population based study from 1989 to 2013.
abstract: BACKGROUND
  There is substantial evidence of a negative impact of maternal chronic disease during pregnancy on reproductive outcomes. Knowledge of the prevalence of chronic diseases during pregnancy is limited, but essential for a focused preventive effort regarding optimal disease control during pregnancy. We aimed to analyze the prevalence of chronic diseases during pregnancy.
  
  
  METHODS
  This register-based cohort study included all women giving birth in Denmark between 1989 and 2013 based on data from Danish health registers. Maternal chronic diseases included 23 disease categories of both physical and mental health conditions recorded within a period of 10 years before childbirth.
  
  
  RESULTS
  We included 1 362 200 childbirths during the study period. The overall prevalence of maternal chronic disease increased from 3.71% in 1989 to 15.76% in 2013. The most frequently registered chronic diseases were chronic lung diseases/asthma (1.73%), thyroid disorders (1.50%) and anxiety and personality disorders (1.33%). Taking increasing maternal age at birth into account, the relative risk for women to have a chronic disease from 2009 to 2013 was 4.14 (95% CI 4.05-4.22), compared with mothers giving birth from 1989 to 1993.
  
  
  CONCLUSIONS
  We found an increasing prevalence of maternal chronic disease during pregnancy and more than a four-fold increased risk of maternal chronic disease during pregnancy for childbirths in the period 2009 through 2013, compared with 1989 through 1993. The main limitation of our study is related to a potentially greater awareness and hence more careful registration of maternal chronic disease over time and thereby an increased tendency to register diseases.
authors: Center for Clinical Epidemiology, Odense University Hospital, Odense, Denmark. line.joelving@rsyd.dk.|Research Unit of Clinical Epidemiology, Institute of Clinical Research, University of Southern Denmark, Odense, Denmark. line.joelving@rsyd.dk.
authors: Line Riis
authors: LR
authors: Jølving
authors: Center for Clinical Epidemiology, Odense University Hospital, Odense, Denmark.|Research Unit of Clinical Epidemiology, Institute of Clinical Research, University of Southern Denmark, Odense, Denmark.
authors: Jan
authors: J
authors: Nielsen
authors: Department of Obstetrics and Gynecology, Herlev University Hospital, Copenhagen, Denmark.|University of Copenhagen, Copenhagen, Denmark.
authors: Ulrik Schiøler
authors: http://orcid.org/0000-0003-3868-106X
authors: US
authors: Kesmodel
authors: Hans Christian Andersen Children's Hospital, Odense University Hospital, Odense, Denmark.|Research Unit of Pediatrics, Institute of Clinical Research, University of Southern Denmark, Odense, Denmark.
authors: Rasmus Gaardskaer
authors: RG
authors: Nielsen
authors: Hans Christian Andersen Children's Hospital, Odense University Hospital, Odense, Denmark.|Research Unit of Pediatrics, Institute of Clinical Research, University of Southern Denmark, Odense, Denmark.
authors: Signe Sparre
authors: SS
authors: Beck-Nielsen
authors: Center for Clinical Epidemiology, Odense University Hospital, Odense, Denmark.|Research Unit of Clinical Epidemiology, Institute of Clinical Research, University of Southern Denmark, Odense, Denmark.
authors: Bente Mertz
authors: BM
authors: Nørgård
mesh_terms: D000293:Adolescent; D000328:Adult; D002908:Chronic Disease; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D015995:Prevalence; D012042:Registries; D055815:Young Adult
keywords: Clinical epidemiology; maternal disease; pregnancy; prevalence; reproduction