Statistical analyses
Maternal demographic characteristics and clinical factors were compared
between venous thrombosis cases and control groups. Continuous variables
were described by mean with standard deviation (SD) or median with
interquartile range (IQR). Categorical variables were described by
frequencies (%). Analysis of variance or Kruskal-Wallis H tests were
performed for continuous data, and chi-square tests or Fisher’s exact
tests were performed for categorical data.
Multivariate log-binomial regression models were used to estimate the
adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for
separately PE alone, DVT (including DVT and concomitant PE) and all VTE
events across GWG in different periods of pregnancy. Regression model
were adjusted for only co-variables with p <0.2 (maternal age,
parity, ART, delivery mode, fetal
number, birthweight, PIH, GDM and postpartum hemorrhage). Interaction
effects between GWG and other covariates (parity, birthweight, maternal
age and delivery mode) on venous thrombosis were also tested.
All analyses were performed using the Statistical Analysis System (SAS)
for Windows, version 9.4 (SAS Institute, Cary, NC). P<0.05 was
considered statistically significant.