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Table 3 Sensitivity analyses of the outcome of congenital malformations following exposure to oseltamivir in pregnancy

From: Oseltamivir in pregnancy and birth outcomes

  Conventional regression analysis Propensity-score matched regression analysis
Unexposed Exposed Odds ratio (95% CI) a Unexposed Exposed Odds ratio (95% CI)b
Analysis including pregnancies terminated due to congenital malformations (2007-2013), prespecified
 Number 521,037 432   432 432  
 Any major congenital malformation 16,692 (3.2%) 22 (5.1%) 1.58 (1.03 to 2.44) 20 (4.6%) 22 (5.1%) 1.10 (0.60 to 2.02)
 Congenital heart defects 3005 (0.6%) 8 (1.9%) 3.17 (1.57 to 6.40) 4 (0.9%) 8 (1.9%) 2.00 (0.60 to 6.64)
Pregnancies among women without an earlier pregnancy resulting in a malformed child, post hoc
 Number 650,431 390   381 381  
 Any major malformation 23,712 (3.7%) 18 (4.6%) 1.26 (0.77 to 2.04) 20 (5.3%) 17 (4.5%) 0.84 (0.43 to 1.64)
 Congenital heart defects 4598 (0.7%) 8 (2.1%) 2.68 (1.27 to 5.68) 5 (1.3%) 7 (1.8%) 1.50 (0.42 to 5.32)
First trimester exposure to oseltamivir, defined as oseltamivir dispensing during 4-10 weeks of gestation, post hoc
 Number 670,602 212   205 205  
 Any major malformation 24,773 (3.7%) 8 (3.8%) 0.91 (0.43 to 1.95) 8 (3.9%) 7 (3.4%) 0.88 (0.32 to 2.41)
 Congenital heart defects 4795 (0.7%) 5 (2.4%) 2.70 (1.00 to 7.29) N/A
Oseltamivir dispensing in second or third trimester (post-organogenesis), prespecified
 Number 670,602 1449   1420 1420  
 Any major malformation 24,773 (3.7%) 64 (4.4%) 1.18 (0.91 to 1.53) 51 (3.6%) 61 (4.3%) 1.21 (0.82 to 1.77)
 Congenital heart defects 4795 (0.7%) 21 (1.5%) 2.10 (1.36 to 3.24) 6 (0.4%) 21 (1.5%) 3.50 (1.41 to 8.67)
Exposure to oseltamivir between 12 and 3 months preconception, post hoc
 Number 669,934 538   530 530  
 Any major malformation 24,745 (3.7%) 24 (4.5%) 1.20 (0.80 to 1.80) 19 (3.6%) 24 (4.5%) 1.28 (0.69 to 2.37)
 Congenital heart defects N/A
First-trimester exposure to penicillin, post hocc
 Number 471,117 70,309   Analysis not conducted
 Any major malformation 17,148 (3.6%) 2798 (4.0%) 1.09 (1.04 to 1.13)
 Congenital heart defects 3296 (0.7%) 599 (0.9%) 1.17 (1.07 to 1.29)
  1. CI confidence interval, N/A not applicable (counts too low to report)
  2. aAdjusted for age at conception, parity, smoking, marital status, obesity, prior delivery of a child with a malformation, respiratory diseases, any other chronic illness (cardiovascular disease, haematological disease, diabetes, neurological disease [including use of antidepressants or antiepileptics], liver or kidney disease, rheumatic disease, or inflammatory bowel disease) during 12 months before conception
  3. bVariables included in estimation of propensity scores are listed in the Additional file 1
  4. cExposure to penicillin for malformations (any, congenital heart defects) among live born and stillborn infants conceived and delivered in 2002-2013 in Denmark