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

Table 3 Decomposition of the total effect of ART on the odds of TOF into a direct effect and indirect effect mediated through multiple pregnancies

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	1.9	1.2 – 3.1	2.6	1.5 – 4.5	1.7	1.0 – 2.8	2.1	1.2 – 3.7	1.1	1.0 – 1.4	1.2	1.0 – 1.5	20.9%
IO^$ only	1.4	0.7 – 2.9	2.1	1.0 – 4.7	1.3	0.7 – 2.6	1.8	0.9 – 3.9	1.1	1.0 – 1.2	1.2	1.0 – 1.3	19.1%
IVF^£ only	2.2	1.0 – 4.7	2.8	1.2 – 6.7	1.8	0.8 – 3.8	2.1	0.9 – 5.2	1.2	0.9 – 1.6	1.3	1.1 – 1.7	27.8%
IVF+ICSI^¥	3.1	1.0 – 10.0	3.5	1.1 – 11.2	2.8	0.9 – 8.9	3.1	0.9 – 10.1	1.1	1.0 – 1.3	1.1	0.9 – 1.4	11.1%
IVF +/- ICSI	2.4	1.3 – 4.6	3.0	1.6 – 5.8	2.1	1.0 – 4.3	2.4	1.2 – 4.6	1.2	0.9 – 1.5	1.3	1.0 – 1.6	22.3%

*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