For Peer Review Only Journal: BMJ Open
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BMJ Open BMJ Open: first published as 10.1136/bmjopen-2012-001185 on 19 July 2012. Downloaded from Beta-blocker treatment during pregnancy and adverse pregnancy outcomes: a nationwide population based cohort study For peer review only Journal: BMJ Open Manuscript ID: bmjopen-2012-001185 Article Type: Research Date Submitted by the Author: 20-Mar-2012 Complete List of Authors: Meidahl Petersen, Kasper; Rigshospitalet, University Hospital Copenhagen, Department of Clinical Pharmacology, Q Jimenez-Solem, Espen; Bispebjerg Hospital, Laboratory of Clinical Pharmacology Andersen, Jon Traerup; Bispebjerg Hospital, Department of Clinical Pharmacology Petersen, Morten; Bispebjerg Hospital, Department of Clinical Pharmacology Brødbæk, Kasper; Bispebjerg Hospital, Department of Clinical Pharmacology; Rigshospitalet, Laboratory of Clinical Pharmacology Poulsen, Henrik; Bispebjerg Hospital, Department of Clinical Pharmacology; Rigshospitalet, Laboratory of Clinical Pharmacology K�ber, Lars; Rigshospitalet, Department of Cardiology http://bmjopen.bmj.com/ Torp-Pedersen, Christian; Gentofte Hospital, Department of Cardiology <b>Primary Subject Pharmacology and therapeutics Heading</b>: Secondary Subject Heading: Epidemiology, Evidence based practice CLINICAL PHARMACOLOGY, Maternal medicine < OBSTETRICS, Keywords: EPIDEMIOLOGY on September 26, 2021 by guest. Protected copyright. For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 1 of 22 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2012-001185 on 19 July 2012. Downloaded from 1 2 3 4 Beta-blocker treatment during pregnancy and adverse pregnancy outcomes: a nationwide 5 population-based cohort study 6 7 8 9 Kasper Meidahl Petersen MB1; Espen Jimenez-Solem MD1; Jon Trærup Andersen MD1; 10 11 Morten Petersen MD1, PhD; Kasper Brødbæk MD1; Henrik Enghusen Poulsen MD, DMSc1; 12 13 Lars Køber MD, DMSc2; Christian Torp-Petersen MD, DMSc3 14 15 For peer review only 16 17 18 Author affiliations 19 20 1: Department of Clinical Pharmacology, Q, Rigshospitalet, University Hospital Copenhagen, 21 22 Denmark 23 24 25 2: Department of Cardiology, Rigshospitalet, University Hospital Copenhagen, Denmark 26 27 3: Department of Cardiology, Gentofte Hospital, Gentofte, Denmark 28 29 30 31 Keywords (MeSH): Adrenergic beta-antagonists, pregnancy, small for gestational age infant, 32 premature birth, perinatal mortality. 33 http://bmjopen.bmj.com/ 34 35 Words: 2995 36 37 38 Correspondence to: 39 Kasper Meidahl Petersen 40 Department of Clinical Pharmacology, Q 41 Rigshospitalet, University Hospital Copenhagen on September 26, 2021 by guest. Protected copyright. 42 Tagensvej 20 43 DK-2200 Copenhagen N 44 Denmark 45 46 Tel +45 5123 7716 47 Fax +45 3545 2745 48 E-mail: [email protected] 49 50 51 52 53 54 55 56 57 58 59 1 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 2 of 22 BMJ Open: first published as 10.1136/bmjopen-2012-001185 on 19 July 2012. Downloaded from 1 2 3 4 5 6 ABSTRACT 7 8 Objective: To investigate the association between exposure to beta-blockers during pregnancy and 9 10 11 the risk of being born small for gestational age (SGA), preterm birth, and perinatal mortality in 12 13 a nationwide cohort. 14 15 Design: A population-basedFor peer retrospective cohortreview study, using the Danishonly Fertility Database. We 16 17 identified all pregnant women redeeming a prescription for beta-blockers using the National 18 19 20 Prescription Registry. Multivariate logistic regression models were used to assess the association 21 22 between exposure and our outcomes. 23 24 Setting: Register based survey. 25 26 Participants: 911685 births between 1995 and 2008 obtained from the Danish Fertility Database. 27 28 Outcome measures: Being born SGA was defined as having a birth weight below the tenth 29 30 th 31 percentile for the corresponding gestational week. Preterm birth was defined as birth before the 37 32 33 gestational week. Perinatal mortality was defined as either death occurring within the first 28 days http://bmjopen.bmj.com/ 34 35 of life, or stillbirth. Before 2004, foetal deaths were recorded as stillbirths if they occurred after 28 36 37 weeks of gestation, but since then stillbirth is recorded for deaths after 22 gestational weeks. 38 39 40 Results: We identified 2459 pregnancies exposed to beta-blockers. Beta-blocker exposure during 41 on September 26, 2021 by guest. Protected copyright. 42 pregnancy was found to be associated with increased risk of SGA; adjusted OR=1.97 (95% CI, 43 44 1.75–2.23), preterm birth; adjusted OR=2.26 (95% CI, 2.03–2.52) and perinatal mortality; adjusted 45 46 OR=1.89 (95 % CI, 1.25–2.84). Analyses were adjusted for socio-economic and maternal variables. 47 48 We found similar risk profiles for pregnancies exposed to labetalol and for pregnancies exposed to 49 50 51 other beta-blockers. 52 53 Conclusion: We found that exposure to beta-blockers during pregnancy was associated with being 54 55 born SGA, preterm birth and perinatal mortality. Our findings show that labetalol is not safer than 56 57 58 59 2 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 3 of 22 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2012-001185 on 19 July 2012. Downloaded from 1 2 3 4 other beta-blockers during pregnancy, and future treatment of pregnant women with beta-blockers 5 6 should therefore be based primarily on the individual needs of the mother and not the unborn child. 7 8 9 ARTICLE SUMMARY 10 11 12 Article focus 13 14 • There is contradictory evidence concerning the consequences of beta-blocker treatment 15 For peer review only 16 during pregnancy. 17 18 • This survey explores the effects of beta-blocker exposure during pregnancy in a Danish birth 19 20 21 cohort comprising all births in Denmark between 1995 and 2008. In addition we compared 22 23 risks associated with exposure to labetalol with exposure to other beta-blockers. 24 25 Key messages 26 27 • Redeeming prescriptions of beta-blockers was found to be significantly associated with 28 29 increased risk of being born SGA, preterm birth, and perinatal mortality. 30 31 32 • We found comparable risk profiles in labetalol-exposed pregnancies and in pregnancies 33 http://bmjopen.bmj.com/ 34 exposed to any other beta-blocker. 35 36 Strengths and limitations of this study 37 38 39 • This study is the largest of its kind to date, and covers an entire nation which minimises risk 40 of selection bias. 41 on September 26, 2021 by guest. Protected copyright. 42 43 • Given the study design, we were not able to adjust for treatment indication and severity of 44 45 maternal disease, nor were we able to rule out confounding by indication, the underlying 46 47 maternal disease, as a possible explanation for our findings. 48 49 50 51 52 53 INTRODUCTION 54 55 56 57 58 59 3 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 4 of 22 BMJ Open: first published as 10.1136/bmjopen-2012-001185 on 19 July 2012. Downloaded from 1 2 3 4 Beta-blockers are widely used in the treatment of chronic hypertension,[1-4] migraine,[5] essential 5 6 tremor[6], and various other conditions. There is contradictory evidence concerning the 7 8 consequences of beta-blocker treatment during pregnancy. Some studies report an association 9 10 11 between beta-blocker treatment and small for gestational age (SGA) newborns, and preterm 12 13 birth,[4,7-10] while others do not.[2,11] Preterm birth and being born SGA are both associated with 14 15 increased risk ofFor perinatal mortality.[12,13]peer reviewWe set out to investigate only whether the use of beta- 16 17 blockers during pregnancy was associated with being born SGA, preterm birth and perinatal 18 19 20 mortality in a nationwide survey between 1995 and 2008. 21 22 23 24 METHOD 25 26 Study population 27 28 We used data obtained from three nationwide registries: the Danish Fertility Database,[14] the 29 30 31 Danish National Hospital Register[15], and the National Prescription Register.[16] Data concerning 32 33 income and educational level were obtained respectively from the Income Statistics Register[17] http://bmjopen.bmj.com/ 34 35 and the Danish Education register,[18] both of which are provided by Statistics Denmark. In 36 37 Denmark all citizens are given a unique ten-digit identification number at birth.[19] This number 38 39 40 can be used to link information between nationwide registers. 41 on September 26, 2021 by guest. Protected copyright. 42 Using the Danish Fertility Database we identified 974 805 births between 1995 and 2008. We 43 44 removed 52 603 records lacking information on pregnancy duration and 7681 records with coding 45 46 errors. In addition, we excluded 2836 records with pregnancy-induced hypertension, defined as 47 48 having redeemed an antihypertensive drug prescription after the twentieth week of gestation, but 49 50 51 never before. The final study population thus comprised 911 685 births. 52 53 The Danish Fertility Database contains information on maternal age, date of birth, and 54 55 previous births, as well as on each child’s sex, gestational age, weight, and mortality.[14] 56 57 58 59 4 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 5 of 22 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2012-001185 on 19 July 2012. Downloaded from 1 2 3 4 Time of conception is based on ultrasound estimates in early pregnancy, or information on last 5 6 menstrual period. 7 8 Information on redeemed prescriptions was retrieved from the National Prescription Register, 9 10 11 which holds information on date of redemption, quantity, strength, and form.[16] Drugs are coded 12 13 in accordance with the Anatomical Therapeutic Chemical (ATC) classification.