Table 1 Characteristics of study infants according to sex.
| Variable | Male (n = 42) | Female (n = 34) | Difference* (95% CI) | p Value |
|---|---|---|---|---|
| Gestational age (weeks) | 26.4 (1.5) | 26.4 (1.4) | 0.02 (−0.93 to 0.97) | 0.960 |
| Birth weight (g) | 833 (187) | 877 (161) | −44 (−155 to 67) | 0.282 |
| Birthweight SDS† | −0.81 (0.97) | −0.17 (0.85) | −0.64 (−1.22 to −0.06) | 0.003 |
| Below 10th birthweight centile‡ | 24% | 9% | 15% (−1% to 31%) | 0.126 |
| Randomised to HFOV | 57% | 53% | 4% (−18% to 27%) | 0.714 |
| Multiple birth | 14% | 29% | −15% (−34% to 3%) | 0.108 |
| Days ventilated¶ | 17.0 | 6.9 | 2.45 (1.37 to 4.38) | 0.003 |
| O2 dependent at 36 weeks PMA | 69% | 47% | 22% (0% to 44%) | 0.052 |
| O2 dependent at discharge | 29% | 6% | 23% (7% to 38%) | 0.016 |
| White ethnic group | 79% | 68% | 11% (−9% to 31%) | 0.282 |
| Smoking in pregnancy | 24% | 14% | 10% (−9% to 28%) | 0.343 |
| Maternal smoking after birth | 24% | 18% | 6% (−14% to 26%) | 0.585 |
| Corrected age at measurement (months) | 12.55 (0.86) | 12.59 (0.99) | −0.04 (−0.46 to 0.38) | 0.849 |
| Length at measurement (cm) | 73.34 (2.96) | 75.24 (2.74) | −1.90 (−3.22 to −0.58) | 0.005 |
| Weight at measurement (kg) | 8.54 (1.15) | 9.25 (1.34) | −0.71 (−1.28 to −0.14) | 0.016 |
Values are mean (SD) or percentages.
*Differences in means and proportions are expressed as male minus female.
†Standard deviation score, standardised for gestational age and sex.19
‡Below 10th centile for gestational age and sex.19
¶Geometric mean used as variable is skewed. Difference is expressed as a ratio of geometric means male/female.
HFOV, High frequency oxygen ventilation; PMA, postmenstrual age.