Table 2.

Interaction between Placental Telomere Length (PTL) and Mitochondrial DNA Copy Number (mtDNA CN) on Risk of Placental Abruption (PA)

	PA Cases (N=105)	Controls (N=73)	Stratified Analysis		Joint Analysis
			Unadjusted OR (95% CI)	Adjusted OR (95% CI)*	Unadjusted OR (95% CI)	Adjusted OR (95% CI)*
Below median mtDNA CN, Above median placental telomere length	18	22	1.00 (reference)	1.00 (reference)	1.00 (reference)	1.00 (reference)
Below median mtDNA CN, Below median placental telomere length	31	14	2.71 (1.12, 6.57)	3.07 (1.13, 8.38)	2.71 (1.12, 6.57)	3.11 (1.17, 8.30)
Above median mtDNA CN, Above median placental telomere length	26	15	1.00 (reference)	1.00 (reference)	2.12 (0.87, 5.16)	2.25 (0.84, 6.00)
Above median mtDNA CN, Below median placental telomere length	30	22	0.79 (0.34, 1.82)	0.71 (0.28, 1.83)	1.67 (0.73, 3.83)	1.61 (0.64, 4.05)
P-value for interaction					0.048	0.032

^*Adjusted for maternal age, gestational age at delivery, mode of delivery, and pre-pregnancy body mass index.

Placental mtDNA copy number: Low: < median (< 84.92) in primary period of collection and (<102.53) in secondary period of collection; high: ≥ median (≥84.92) in primary period of collection and (≥102.53) in secondary period of collection. Placental telomere length: high: ≥ median (≥2.32) in batch 1 and (≥1.42) in batch 2; low: < median (<2.32) in batch 1 and (<1.42) in batch 2.