Stillbirth and factor V Leiden - A regional based prospective evaluation.

BACKGROUND

Approximately 10% of Swedes are carriers of coagulation factor V Leiden (FVL). It has been suggested that carriers are at an increased risk of stillbirth. We aimed to assess the risk of stillbirth in carriers of FVL as compared to non-carriers.

METHODS

A consecutive registration of all stillbirths from 2001 to 2015 in the whole Stockholm region has been performed. A FVL blood sample, an autopsy and histopathological examination of the placenta was scheduled to be offered all women with stillbirth. Main outcome was the difference in carriership of FVL between cases with live- vs. stillbirth. The primary cause of death was determined according to the Stockholm hierarchical classification of stillbirth.

RESULTS

The incidence of stillbirth was 3.6‰. Out of the 1392 cases of stillbirth occurring during the study period, FVL status was determined in 963 women. Of these 74 (7.7%) were carriers of FVL as compared to 8.1% in the control group (p = 0.6). A primary cause of death due to infection was twice as common among non-carriers compared to carriers of FVL (odds ratio [OR] = 2.3, 95% CI 1.08-4.8). In the whole study group, the prevalence of SGA was 14-fold increased among stillbirths as compared to live births (OR = 13.9, 95% CI 12.4-15.6).

CONCLUSION

Maternal FVL carriership was not related to an increased risk of stillbirth. However, a diagnosis of primary cause of death due to infection was less likely among FVL carriers.