Table 2. Primary and secondary neonatal outcomes by study group.
| Outcome | Progesterone n = 406 | Placebo n = 393 | Unadjusted Treatment Effect for Progesterone versus Placebo (95% CI) | Unadjusted p-Value | Adjusted Treatment Effect for Progesterone versus Placebo (95% CI) | Adjusted p-Value# | |
|---|---|---|---|---|---|---|---|
| Primary Outcomes | |||||||
| Neonatal RDS | 42/402 (10.5) | 41/388 (10.6) | 0.99 (0.65–1.51) | 0.958 | 0.98 (0.64–1.49) | 0.912 | |
| Severity of respiratory disease* | 1.03 (0.69–1.53) | 0.883 | 1.02 (0.69–1.53) | 0.905 | |||
| Nil | 338/402 (84.1) | 327/388 (84.3) | |||||
| Mild | 24/402 (6.0) | 28/388 (7.2) | |||||
| Moderate | 32/402 (8.0) | 26/388 (6.7) | |||||
| Severe | 8/402 (2.0) | 7/388 (1.8) | |||||
| Secondary Outcomes | |||||||
| Other Respiratory Measures | |||||||
| Oxygen therapy | 43/402 (10.7) | 45/388 (11.6) | 0.92 (0.61–1.38) | 0.696 | 0.92 (0.62–1.37) | 0.670 | |
| Duration of oxygen therapy** | 4.96 (38.0) | 5.43 (45.7) | 0.91 (0.29–2.84) | 0.875 | 0.85 (0.32–2.29) | 0.751 | |
| Highest FiO2 at <12 hours of birth‡ | 29.6 (13.9) | 27.9 (13.0) | 1.68 (−3.03 to 6.38) | 0.485 | 1.37 (−2.97 to 5.71) | 0.536 | |
| Mechanical ventilation | 26/402 (6.5) | 23/388 (5.9) | 1.09 (0.62–1.92) | 0.763 | 1.08 (0.62–1.89) | 0.788 | |
| Duration of mechanical ventilation (days)** | 0.50 (3.0) | 0.70 (4.8) | 0.72 (0.29–1.79) | 0.477 | 0.51 (0.21–1.24) | 0.137 | |
| Surfactant used | 26/402 (6.5) | 25/388 (6.4) | 1.00 (0.58–1.74) | 0.989 | 0.99 (0.58–1.72) | 0.984 | |
| Nitric oxide for respiratory support | 0/402 (0.0) | 3/388 (0.8) | N/A | 0.118^ | N/A | N/A | |
| Air leak syndrome | 2/402 (0.5) | 1/388 (0.3) | N/A | 1.000^ | N/A | N/A | |
| Chronic lung disease | 10/402 (2.5) | 7/388 (1.8) | 1.38 (0.49–3.87) | 0.542 | N/A | N/A | |
| Adverse Infant Outcomes | |||||||
| Serious infant outcome (composite) | 155/406 (38.2) | 152/393 (38.7) | 0.99 (0.82–1.18) | 0.887 | 0.98 (0.82–1.17) | 0.798 | |
| Preterm birth at <37 weeks’ gestation | 148/406 (36.5) | 146/393 (37.2) | 0.98 (0.81–1.18) | 0.842 | 0.97 (0.81–1.17) | 0.765 | |
| Perinatal mortality | 5/406 (1.2) | 7/393 (1.8) | 0.69 (0.22–2.16) | 0.526 | N/A | N/A | |
| Stillbirth | 4/406 (1.0) | 5/393 (1.3) | N/A | 0.749^ | N/A | N/A | |
| Infant death | 1/406 (0.3) | 2/393 (0.5) | N/A | 0.619^ | N/A | N/A | |
| Born by caesarean section | 126/406 (31.0) | 105/393 (26.7) | 1.16 (0.93–1.45) | 0.187 | 1.17 (0.94–1.46) | 0.160 | |
| Apgar score < 4 at 5 minutes | 6/406 (1.5) | 6/393 (1.5) | 0.97 (0.31–2.98) | 0.955 | N/A | N/A | |
| Birth weight (g) ‡ | 2870.2 (849.2) | 2926.5 (794.2) | −56.3 (−174.9 to 62.4) | 0.353 | −53.6 (−171.7 to 64.4) | 0.373 | |
| Birth weight z-score‡ | 0.13 (1.1) | 0.20 (1.0) | −0.07 (−0.22 to 0.07) | 0.333 | −0.07 (−0.21 to 0.08) | 0.356 | |
| Birth weight < 3rd centile | 8/402 (2.0) | 7/388 (1.8) | 1.10 (0.38–3.19) | 0.856 | N/A | N/A | |
| Any IVH | 9/402 (2.2) | 9/388 (2.3) | 0.97 (0.39–2.41) | 0.939 | N/A | N/A | |
| Grade 3/4 IVH | 1/402 (0.3) | 1/388 (0.3) | N/A | 1.000^ | N/A | N/A | |
| Periventricular leucomalacia | 0/402 (0.0) | 1/388 (0.3) | N/A | 0.491^ | N/A | N/A | |
| Inotropic support for PDA | 11/402 (2.7) | 9/388 (2.3) | 1.18 (0.47–2.96) | 0.725 | N/A | N/A | |
| Necrotising enterocolitis | 2/402 (0.5) | 2/388 (0.5) | N/A | 1.000^ | N/A | N/A | |
| Proven early neonatal sepsis | 0/402 (0.0) | 2/388 (0.5) | N/A | 0.241^ | N/A | N/A | |
| Retinopathy of prematurity | 12/401 (3.0) | 9/386 (2.3) | 1.28 (0.51–3.26) | 0.600 | N/A | N/A | |
| Admission to NICU | 68/402 (16.9 | 71/388 (18.3) | 0.92 (0.68–1.27) | 0.624 | 0.92 (0.67–1.25) | 0.591 | |
| Infant postnatal length of stay (days)** | 11.93 (21.1) | 11.24 (21.6) | 1.06 (0.80–1.41) | 0.677 | 1.06 (0.79–1.41) | 0.717 | |
Denominators are 406 in the progesterone group and 393 in the placebo group for outcomes that include all infants alive at the time of randomisation and 402 and 388, respectively, for outcomes relating to only live-born infants (where the 4 stillbirths in the progesterone group and 5 stillbirths in the placebo group are not included). Values are number (percentage), and treatment effects are relative risks unless otherwise indicated. Abbreviations: CI, confidence interval; FIO2, fractional inspired oxygen; GA, gestational age; IVH, intraventricular haemorrhage; N/A, not available; NICU, neonatal intensive care unit; PDA, patent ductus arteriosus; RDS, respiratory distress syndrome.
# Adjusted for GA at randomization, GA of previous preterm birth, and reason for previous preterm birth.
* Values are number (percentage), and treatment effects are odds ratios of higher severity.
** Values are mean (standard deviation), and treatment effects are ratios of means.
‡ Values are mean (standard deviation), and treatment effects are differences in means.
^ p-Value from Fisher's exact test.