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. Author manuscript; available in PMC: 2021 Sep 1.
Published in final edited form as: Epidemiology. 2020 Sep;31(5):636–643. doi: 10.1097/EDE.0000000000001222

Figure 1. Causal directed acyclic graphs (DAGs) showing the effect of fertility treatments on neonatal complications.

Figure 1.

A denotes the treatment (1 for letrozole, 0 for gonadotropin), D the competing event (1 if no livebirth occurs, 0 otherwise), Y the outcome (1 if neonatal complications occur, 0 otherwise), U a set of unmeasured factors that affect both the probability of live birth and of neonatal complications, e.g., partner’s semen quality, maternal health status, or a genetic factor, AY is the component of A that directly affects neonatal complications, and AD is the component of A that directly affects live birth. Graph ii is an extended version of the graph i, in which the treatment components AY and AD are deterministic functions (bold arrows) of A.