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Table 3 Subgroup analysis of association between exposure to HPV Vaccination and spontaneous abortion

From: Peri-conceptional or pregnancy exposure of HPV vaccination and the risk of spontaneous abortion: a systematic review and meta-analysis

  Number of studies included Vaccine exposure group (total, n) Vaccine exposure group (SA, n) Control group (total, n) Control group (SA, n) RR 95% CI I 2 RD (%) 95% CI (%) I 2
2vHPV (Pre-90 days to pregnancy end)
 Data source
 Clinical Trials base 2 846 121 3676 464 1.16 0.88–1.55 42.7 2.0 −1.7-5.7 43.5
 Database 1 330 34 632 57 1.14 0.76–1.71 1.3 −2.7-5.3
 Adjusted data or not
 Adjusted a 2 711 84 3859 471 1.03 0.90–1.19 0.0
 Unadjusted 1 465 71 449 50 1.37 0.98–1.39
4vHPV (Pre-45 days to pregnancy end)
 Data source
 Clinical trials base 2 213 31 1486 180 0.85 0.57–1.27 0.0 −2.2 −7.8-3.4 0.0
 Database 2 2344 207 2771 209 0.89 0.72–1.09 20.2 −1.0 −2.7-0.7 0.0
 Adjusted data or not            
 Adjusted a 2 2344 207 2771 209 1.06 0.85–1.32 13.7
 Unadjusted 2 213 31 1486 180 0.85 0.57–1.27 0.0
  1. a adjusted by age at conception, 2vHPV bivalent HPV vaccine, 4vHPV quadrivalent HPV vaccine, LMP Last menstrual period, SA Spontaneous abortion, RR Relative risk, RD Risk difference