Preterm delivery
There were 26 studies included in the preterm birth (PTB) meta-analysis. This included 7728 pregnancies exposed to biologics and 18574 disease matched controls (Table 1). The proportion of PTB in the treated group was 12% (95% CI 0.10 to 0.14), 10% (0.09 to 0.012) in the disease matched and 6% (0.04 to 0.07) in the disease free group (Figure S4). There was no statistical difference in the treated group vs the disease matched group (p=0.250), there was a statistical difference when comparing disease free with disease treated women (p= 0.008 Table S1).
Subgroup analysis examining anti-TNF-α only revealed a change in the PTB rate for the treated group to 11% (95% CI 0.09 to 0.13) (Figure 2). Subgroup analysis by disease classification showed anti-TNF-α treated IBD had a PTB rate of 9% (0.07 to 0.11) with the disease matched IBD group having a PTB rate of 9% (0.08 to 0.010) (Figure S5). Only one study focused on anti-TNF-α use and RA17 with a treated PTB rate of 18% (0.14 to 0.24) and disease matched of 14% (0.12 to 0.15). The remaining studies focused on mixed CID with a preterm birth rate of 12% (0.09 to 0.15).