Table 1.

Baseline Characteristics of the Study Population

Characteristic	Progesterone Group (n = 121)	Non-Treatment Group (n = 253)	p-value
Maternal Age (years, mean ± SD)	29.3 ± 5.8	28.3 ± 5.6	0.119
Nulliparity (n, (%))	55 (45.4)	114 (45.0)	0.910
Gravidity (n, mean ± SD)	2.74 ± 1.91	2.69 ± 2.06	0.815
Prior Caesarian Delivery (n, (%))	8 (6.6)	22 (8.6)	0.676
Prior Preterm Births (n, (%))	29 (24.4)	43 (17.1)	0.097
GA* at Diagnosis (weeks, mean ± SD)	29.82 ± 2.59	31.18 ± 2.23	< 0.001
GA at Diagnosis, Categorized (n, (%))			< 0.001
- Prior to 30 weeks	59 (48.7)	60 (23.7)
- At 30 weeks or later	62 (51.3)	193 (76.3)
Cervical Length at Diagnosis (mm, mean ± SD, median [range], [IQR])	19.5 ± 4.4	20.5 ± 4.2	0.062
	20 [3–25]	22 [3–25]
	[17–23]	[18–24]
Severe Short Cervix** (n, (%))	21 (17.5)	33 (13.0)	0.071
Cervical Length – Categorized			0.044
- 0–9 mm	3 (2.5)	4 (1.6)
- 10–19 mm	50 (41.3)	75 (29.6)
- 20–25 mm	68 (56.2)	174 (68.8)

^*GA = gestational age.

^**Severe short cervix defined as cervical length of 15 mm or less.