TABLE 1.

Characteristics of First-degree Relatives of Women With Placental Abruption and Controls

Probands and First-degree Relatives	Abruption Cases	Controls
Index probands; no.	212	206
Age (years); mean (SD)	30.2 (6.0)	30.5 (6.3)
Smoking; %	9	4
African-American race; %	18	17
Probands biologic mother; no.	188	170
Age (years); mean (SD)	53.1 (7.3)	52.5 (7.8)
Smoking; %	25	18
African-American race; %	19	17
Probands biologic father; no.	170	159
Age (years); mean (SD)	53.9 (7.6)	54.4 (8.4)
Smoking; %	40	37
African-American race; %	19	20
Probands sisters; no. (range)	258 (1–6)	268 (1–6)
Age (years); mean (SD)	31.5 (9.9)	32.3 (10.2)
Smoking; %	13	13
African-American race; %	11	15
Probands brothers; no. (range)	236 (1–6)	195 (1–9)
Age (years); mean (SD)	31.7 (10.1)	30.6 (11.0)
Smoking; %	25	25
African-American race; %	17	15