Baseline Levels of Serum Progesterone and the First Trimester Pregnancy Outcome in Women with Threatened Abortion: A Retrospective Cohort Study

Table 2

Results of univariate multivariate analysis using binary logistic regression and marginal structural model.

Exposure	Model 1: nonadjusted model (OR, 95% CI, value)	Model 2: fully adjusted model (OR, 95% CI, value)	Model 3: marginal structural model (HR, 95% CI, value)
Progesterone	0.98 (0.98, 0.99) <0.01	0.99 (0.98, 0.99) <0.01	0.99 (0.98, 0.99) <0.01
Progesterone tertile
Low	Ref	Ref	Ref
Middle	0.40 (0.27, 0.59) <0.01	0.47 (0.24, 0.89) <0.05	0.45 (0.19, 1.07) <0.01
High	0.28 (0.18, 0.42) <0.01	0.48 (0.25, 0.92) <0.05	0.35 (0.18, 0.71) <0.01
for trend of	<0.01	<0.05	<0.01

Nonadjusted model: we used basal progesterone, and no covariables were adjusted. Fully adjusted model: we used basal progesterone and adjusted for maternal age, BMI, smoking, drinking, gestational week, marital status, basal β-HCG (log10), gestity, parity, abortion, embryo visualization, cardiac movement visualization, medical history, and use of progesterone. Marginal structural model: we used serial progesterone and adjusted for maternal age, BMI, smoking, drinking, gestational week, marital status, serial β-HCG (log10), gestity, parity, abortion, embryo visualization, cardiac movement visualization, medical history, and use of progesterone.