Table 5.

Additional subgroup analyses for preterm birth prior to 37 and 34 weeks^*

	17-OHP (N=327)	Placebo (N=330)	RR (95% CI)	P**
Preterm birth < 37 weeks
Cervical length				0.59
< 10 mm	5/9 (55.6)	10/16 (62.5)	0.89 (0.44 – 1.78)
10–20 mm	19/50 (38.0)	18/40 (45.0)	0.84 (0.52 – 1.38)
> 20 mm	58/268 (21.6)	52/274 (19.0)	1.14 (0.82 – 1.59)
Preterm birth < 34 weeks
Cervical length				0·82
< 15 mm	9/25 (36·0)	13/31(41.9)	0·86 (0·44–1·67)
≥15 mm	32/302 (10.6)	35/299 (11.7)	0.91 (0·58–1·42)
Cervical length				0·49
< 10 mm	5/9 (55·6)	6/16 (37·5)	1.48 (0·63–3.51)
10–20 mm	11/50 (22·0)	12/40 (30·0)	0·73 (0·36–1·48)
> 20 mm	25/268 (9.3)	30/274 (10.9)	0·85 (0·52–1·41)

^*Data presented as n/N (%)

^**P value for Breslow-Day interaction term