Table 1. Population characteristics and statistical differences between the two studied groups.
| Bodysuit group | Sleepwear group | Mann-Whitney tests | |
|---|---|---|---|
| NB characteristics | |||
| Birth gestational age (weeks + days) | 30 + 3 [27–33 + 5] | 30 + 3 [27 + 4–32 + 4] | U = 35, P = 0.66 |
| Birth weight (grams) | 1460 [935–2165] | 1425 [1035–1680] | U = 27, P = 0.8 |
| Post-natal age (days) when observed | 34.5 [11–59,5] | 34.5 [22–69] | U = 40, P = 1 |
| Weight when observed | 1864 [1415–2303] | 2020 [1605–2304] | U = 20, P = 0.08 |
| Analyzed videos | |||
| Duration (minutes) per baby | 141 [88,5–264] | 163.5 [60.5–343] | U = 28, P = 0.29 |
| Duration (min) on their backa | 107 [14–233] | 125.5 [48.5–343] | U = 28, P = 0.29 |
a: only videos of NB lying on their back were included in the analyses
Bodysuit group, N = 9; Sleepwear group, N = 9 (see text for group description)