Main findings:
Placental abruption (PA) occurs in 1-2% of pregnancies and incurs
considerable maternal and perinatal morbidity and mortality. While the
majority of research underlying the causes of PA has been directed at
evaluating environmental risk factors (e.g. PROM, smoking, prior PA,
hypertension, history of cesarean delivery), recent studies have
assessed genetic causes. 8–16 A pivotal step in the
distinction between environmental and genetic causes for PA is the
estimation of familial risk in a population. We estimated 18-20% as the
inherited odds for PA in FDRs, and 9% and 0-1% respectively, for SDRs
and TDRs. We noted an elevated odds of PA for all degrees of relation
for the highest risk individuals, or individuals who experienced two or
more PAs.
With use of the ego-driven familial analysis, known clinical risk
factors such as PROM, smoking, and hypertension were adjusted for, which
diminished the estimated increased odds of PA for an individual towards
the null (16% vs. 20% with the relative-driven analysis). We see that
these environmental risk factors outweigh genetic heritability at the
second- and third-degree relation level as those estimations were not
statistically significant.