First authorref Skovlund1 Skovlund1 Zettermark2 Zettermark2 Lundin3 Lundin3
Design and population Design and population Design and population Design and population Design and population Design and population
Study design Historical cohort Historical cohort Historical cohort Historical cohort Historical cohort Historical cohort
Study period 2000-2013 2000-2013 2010-2011 2010-2011 2010-2017 2010-2017
Population 1.061.997 1.061.997 815.662 815.662 739.585 739.585
Age group 15-34 years 15-34 years 12-30 years 12-30 years 15-25 years 15-25 years
Person-years 6,832,938 6,832,938 815,662 815,662 3,044,372 3,044,372
Non-use 3,041,595 3,041,595 404,103 404,103 1,947,129 1,947,129
All use 3,791,343 3,791,343 411,559 411,559 1,097,243 1,097,243
Results Results Results Results Results Results
Reference group Non-users Non-users Non-users Non-users Non-users Non-users
Age group (all) 15-34 years 15-34 years 12-30 years 12-30 years 15-25 years 15-25 years
RR  5% CI OR  95% CI RR 95% CI
Oral contraceptives 1.2 1.22-1.25 1.3 1.26-1.33 0.9 0.87-0.91
Transdermal patch 2.1 1.76-2.18 > 1.6 1.45-1.67 1.3 1.21-1.33
Vaginal ring 1.5 1.55-1.69
Progestogen only pill 1.3 1.18-1.37 1.3 1.24-1.33 1.0 0.99-1.06
LNG-IUS 1.4 1.31-1.42 1.5 1.38-1.55 1.3 1.29-1.39
Adolescents 15-19 years 15-19 years 15-17 years 15-17 years 15-19 years 15-19 years
Oral contraceptives 1.8 1.75-1.84 1.5 1.41-1.64 1.0 0.93-0.98
Transdermal patch 3.1 2.56-3.71 > 2.3 1.85-2.79 1.4 1.30-1.58
Vaginal ring 2.9 2.60-3.16
Progestogen only pill 2.1 1.67-2.52 1.8 1.65-2.03 1.1 1.07-1.19
LNG-IUS 3.1 2.47-3.84 2.5 2.10-2.94 1.6 1.46-1.73
Reference group Never users Never users Never users Never users
Age group 15-34 years 15-34 years 15-25 years 15-25 years
Oral contraceptives 1.7 1.66-1.71 NA NA 1.0 0.98-1.02
Transdermal patch 2.6 2,38-2,95 NA NA > 1.3 1.27-1.39
Vaginal ring 2.2 2.14-2.34 NA NA
Progestogen only pill 1.7 1.62-1.87 NA NA 1.1 1.07-1.14
LNG-IUS 1.9 1.80-1.96 NA NA 1.4 1.32-1.42