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Table 4 Decomposition of the total effect of ART on the odds of TOF without associated chromosomal anomalies into a direct effect and indirect effect mediated through multiple pregnancies

From: Assessing the role of multiple pregnancies in the association between tetralogy of Fallot and assisted reproductive techniques: a path-analysis approach

Art Total effect Direct effect Indirect effect Estimated size of the indirect effect
Unadjusted OR* 95% CI Adjusted§ OR* 95% CI Unadjusted OR* 95% CI Adjusted OR* 95% CI Unadjusted OR* 95% CI Adjusted OR* 95% CI
None 1.0 ref. 1.0 ref. 1.0 ref. 1.0 ref. 1.0 ref. 1.0 ref.  
All methods combined 2.3 1.5 – 3.5 3.2 2.1 – 4.7 1.9 1.2 – 3.0 2.5 1.6 – 3.8 1.2 1.0 – 1.4 1.3 1.1 – 1.5 21.5%
IO$ only 1.7 0.9 – 3.1 2.6 1.3 – 5.0 1.5 0.8 – 2.7 2.2 1.2 – 4.0 1.1 1.0 – 1.3 1.2 1.0 – 1.4 18.9%
IVF£ only 2.5 1.1 – 6.1 3.4 1.6 – 7.2 1.9 0.8 – 5.0 2.4 1.2 – 4.8 1.3 1.0 – 1.7 1.4 1.0 – 2.0 29.7%
IVF+ICSI¥ 4.0 1.2 – 13.1 4.4 1.2 – 15.9 3.5 1.1 – 11.5 3.7 1.0 – 13.8 1.1 0.9 – 1.4 1.2 0.9 – 1.5 11.7%
IVF +/- ICSI 2.9 1.6 – 5.4 3.7 2.0 – 7.0 2.3 1.2 – 4.6 2.7 1.5 – 4.9 1.2 1.0 – 1.5 1.4 1.0 – 1.9 23.6%
  1. *Odds ratios (OR) represent the odds of a birth (including live births. stillbirths and pregnancy terminations) with TOF (cases) relative to the odds of a birth with one of the malformed controls (club-foot, angioma, skin abnormality, polydactyly, syndactyly, and congenital hip dislocation).
  2. §Adjustment was made for maternal age, occupation, geographic origin, paternal age and year of birth.
  3. $Inductors of ovulation.
  4. £In vitro fertilization.
  5. ¥IVF with intracytoplasmic sperm injection.