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

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

Art	Total effect				Direct effect				Indirect effect				Estimated size of the indirect effect
Art	Unadjusted OR*	95% CI	Adjusted§ OR*	95% CI	Unadjusted OR*	95% CI	Adjusted OR*	95% CI	Unadjusted OR*	95% CI	Adjusted OR*	95% CI	Estimated size of the indirect effect
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%

*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).
^§Adjustment was made for maternal age, occupation, geographic origin, paternal age and year of birth.
^$Inductors of ovulation.
^£In vitro fertilization.
^¥IVF with intracytoplasmic sperm injection.

ISSN: 1750-1172