Perinatal Risks Associated with Early Vanishing Twin Syndrome following Transfer of Cleavage- or Blastocyst-Stage Embryos

Table 4

Preterm birth and multiple logistic regression to account for confounding variables.

PTB	Standard error	Adjusted OR (95% CI)	P
Age (<35 versus ≥35 years)	0.21	0.87 (0.54–1.41)	0.58
Duration of ovarian stimulation (<9 versus ≥9 days)	0.36	0.83 (0.35–1.97)	0.67
Gonadotropin dose (<2000 versus ≥2000 IU)	0.86	0.93 (0.15–5.71)	0.94
Peak E2 level (<2000 versus ≥2000 pg/Ml)	0.24	1.12 (0.74–1.71)	0.57
Total number of oocytes (<10 versus ≥10)	0.13	0.70 (0.48–1.11)	0.16
Blastocyst-stage ET (yes versus no)	0.21	0.74 (0.42–1.28)	0.28

PTB: preterm birth; : estradiol; ET: embryo transfer.