Statistical analyses
ICH, abnormal foetal loss
ADVERSE EVENTS, PREGNANCY COMPLICATIONS, PREGNANCY COMPLICATIONS, REGRESSION, EVENTS, COMPLICATIONS
All statistical comparisons were made between the HE vaccine group and the HPV vaccine group using Student’s T-test, Chi-Squared test, Fisher’s exact test, Wilcoxon test, or Cochran-Mantel-Haenszel test.Characteristics of women who became pregnant and their pregnancy outcomes and complications were displayed. Women who inadvertently received HE vaccine during pregnancy were matched in a 1:2 ratio to those HE vaccinees who were nonpregnant throughout the study period. The matched factors included age at enrolment (no more than two years of difference), receiving the same HE vaccine doses and study site. The incidences of adverse events in participants vaccinated during pregnancy, as well as in matched nonpregnant women, were summarized.Pregnancy-related adverse events were divided into three parts: abnormal foetal loss outcomes, neonatal abnormality outcomes, and pregnancy complications in focus. To measure the impact of exposure time for pregnancy on adverse pregnancy outcomes and pregnancy complications, exposure types were classified as proximal and distal based on the interval between exposure and pregnancy. Proximal exposure was defined as vaccination during pregnancy or the onset of pregnancy within 90 days post any dose. Odds ratios with 95% confidence intervals were estimated with the use of a logistic regression model, with presence/absence of adverse pregnancy events considered as the dependent variable and the type of vaccine received and maternal age used as independent variables. The primary comparisons included: (1) pregnant women with any HE vaccine exposure vs those with any HPV vaccine exposure; (2) pregnant women with proximal HE vaccine exposure vs those with proximal HPV vaccine exposure; (3) pregnant women with distal HE vaccine exposure vs those with distal HPV vaccine exposure. In addition, comparison of pregnant women having proximal exposure with those having distal exposure was drawn specifically in the HE vaccine group, using the exposure types and maternal age as independent variables. To avoid masking the acute effects of vaccine, we conducted a sensitivity analysis based on defining proximal exposure as vaccination during pregnancy or the onset of pregnancy within 30 days post any dose. All analyses were performed using the generalized estimation equation (GEE) method to account for possible correlations between pregnancies of the same mother. The dependent variable was binomial (presence/absence of adverse pregnancy events), and hence the logit link function was used in the GEE model.Pregnancy complications and adverse events were coded using the Medical Dictionary for Regulatory Activities (MedDRA, version 20.0) developed by ICH. SAS version 9.4 was used for all the analyses. All reported 