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Table 1 Infant and maternal characteristics at original SIFT trial entry

From: Evaluation of the effectiveness of an incentive strategy on the questionnaire response rate in parents of premature babies: a randomised controlled Study Within A Trial (SWAT) nested within SIFT

  Before group
(n = 459)
After group
(n = 464)
Number of centres, n 51 51
Allocated to faster group in SIFT a, n/N (%) 226/459 (49.2) 231/464 (49.8)
Male sex, n/N (%) 229/459 (49.9) 257/463 (55.5)
 Missing 0 1
Median (IQR) Infant age at randomisation in days 4 (3 to 6) 4 (3 to 6)
Birth weight < 10th centile for gestational age, n/N (%) 106/459 (23.1) 77/463 (16.6)
 Missing 0 1
Median (IQR) Gestation at delivery (weeks) 29 (27 to 31) 29 (27 to 30)
Mean (SD) Birth weight (grammes) 1139.5 (331.8) 1131.8 (319.4)
Infant heart rate > 100 bpm at 5 mins, n/N (%) 421/455 (92.5) 418/456 (91.7)
 Missing 4 8
Mean (SD) Infant temperature on admission (°C) 36.8 (0.7) 36.8 (0.8)
 Missing 4 2
Mean (SD) Infant worst base excess within first 24 h of birth − 6.0 (3.9) − 6.1 (4.1)
 Missing 8 10
Infant ventilated via endotracheal tube at randomisation, n/N (%) 90/458 (19.7) 107/463 (23.1)
 Missing 1 1
Infant had absent or reversed end diastolic flow, n/N (%) 76/452 (16.8) 70/455 (15.4)
 Missing 7 9
Mean (SD) Mother’s age at randomisation (years) 30.7 (5.8) 31.2 (6.5)
Multiple pregnancya,b, n/N (%) 144/459 (31.4) 139/464 (30.0)
 Singlesc 0 1
 Twinsd 136 116
 Tripletse 8 22
Caesarean section delivery, n/N (%) 284/459 (61.9) 272/464 (58.6)
Membranes ruptured before labour, n/N (%) 167/453 (36.9) 159/460 (34.6)
 Missing 6 4
Membranes ruptured > 24 h before delivery, n/N (%) 119/454 (26.2) 104/458 (22.7)
 Missing 5 6
  1. aMinimisation factor
  2. bSometimes, only one infant from a multiple pregnancy met the inclusion criteria and was recruited
  3. cNumber of babies from multiple pregnancies where the other foetuses were aborted, miscarried or stillborn
  4. dNumber of babies who were one of twins
  5. eNumber of babies who were one of triplets
  6. Unless otherwise stated the table gives the percentages of infants with data in that group of the trial who had
  7. (or whose mother had) the stated characteristic
  8. IQR denotes 25th percentile to 75th percentile; SD denotes standard deviation; bpm, beats per minute