Population-based estimate of sibling risk for preterm birth, preterm premature rupture of membranes, placental abruption and pre-eclampsia

Table 3 λ_S and sib-sib OR (with 95% CI) for placental abruption.

	All races	White	Black
Population: placental abruption	2050	1579	428
Population: N	268002	220641	42888
Population risk	0.008 (0.008–0.008)	0.007 (0.007–0.007)	0.010 (0.009–0.011)
Siblings: sibpairs with both siblings affected	34	30	4
Siblings: sibpairs with first sibling affected	1124	851	245
Sibling risk	0.030 (0.020–0.040)	0.035 (0.023–0.047)	0.016 (0–0.032)
λ_S	4.0 (2.6–5.3)	4.9 (3.2–6.7)	1.6 (0.0–3.2)
Sib-sib unadjusted OR (95% CI)	4.1 (2.9–5.8)	5.4 (3.8–7.9)	1.4 (0.5–3.7)
Sib-sib adjusted OR (95% CI)#	3.8 (2.6–5.5)	5.0 (3.4–7.4)	1.2 (0.4–3.9)

#Adjusted for mother < 20 or > 35 years old, mother < 12 education, Medicaid (index of low SES), no prenatal care, mother BMI < 20 kg/m², cigarette smoking, insulin-dependent diabetes mellitus, chronic hypertension, hydraminos/oligohydraminos

ISSN: 2730-6844