PB0461 - An association of factor XII deficiency and recurrent pregnancy loss: a systematic review and meta-analysis

Background: Individuals with factor XII deficiency did not exhibit bleeding manifestations, but some studies have demonstrated its association with thrombosis. Furthermore, several reports have indicated an increased risk of recurrent pregnancy loss in women with factor XII deficiency.

Aims: To evaluate the association between Factor XII deficiency and recurrent pregnancy loss.

Methods: The Embase, MEDLINE, and ScienceDirect databases were independently searched by three investigators to identify relevant studies published from inception to July 31, 2023. These trials examined the proportion of patients experiencing recurrent pregnancy loss, comparing those with normal factor XII levels to those with factor XII deficiency. Additionally, the studies reported factor XII levels in at least one group. The definition of recurrent pregnancy loss varied among the included studies (Table 1).

Results: Seven studies were included in the meta-analysis, representing 3,090 patients with recurrent pregnancy loss and 194 patients with normal pregnancies. The pooled prevalence of factor XII deficiency among women with recurrent pregnancy loss was 8.8% (95% CI 5.9-11.7; I2= 81.35%). Furthermore, the mean factor XII levels were analyzed between women with recurrent pregnancy loss (521 patients) and those with normal pregnancy (1,494 patients). Our study showed that factor XII levels in women with recurrent pregnancy loss were lower than in women with successful pregnancies, with a mean difference of -21.76% (95% CI -62.79 to 19.28; I2 = 99%) (Figure 1).

Conclusion(s): Our study demonstrated a potential link between factor XII deficiency and recurrent pregnancy loss. However, further prospective studies are warranted to confirm our findings regarding this association.