Table 3. Secondary Outcomes by Treatment Group, Overall, and Within Specified Subgroups.
| Umbilical Cord Milking |
Delayed Umbilical Cord Clamping |
Risk Difference, % (95% CI) |
P Valuea |
P Value for Interactionb |
|
|---|---|---|---|---|---|
| Infant Death, No./Total No. (%) | |||||
| Overall | 17/236 (7) | 15/238 (6) | 1 (−4 to 5) | .70 | |
| By gestational age at birth strata | |||||
| 23 wk 0 d through 27 wk 6 d | 14/93 (15) | 13/89 (15) | 0 (−10 to 11) | .93 | .68 |
| 28 wk 0 d through 31 wk 6 d | 3/143 (2) | 2/149 (1) | 1 (−2 to 4) | .68 | |
| By mode of delivery subgroups | |||||
| Cesarean | 11/180 (6) | 10/159 (6) | 0 (−5 to 5) | .95 | .43 |
| Vaginal | 6/56 (11) | 5/79 (6) | 5 (−5 to 14) | .36 | |
| Severe Intraventricular Hemorrhage (Grade 3 or 4), No./Total No. (%) | |||||
| Overall | 20/236 (8) | 8/238 (3) | 5 (1 to 9) | .02 | |
| By gestational age at birth strata | |||||
| 23 wk 0 d through 27 wk 6 d | 20/93 (22) | 5/89 (6) | 16 (6 to 26) | .002 | .003 |
| 28 wk 0 d through 31 wk 6 d | 0/143 | 3/149 (2) | −2 (−4 to 1) | .24 | |
| By mode of delivery subgroups | |||||
| Cesarean | 10/180 (6) | 6/159 (4) | 2 (−3 to 6) | .44 | .06 |
| Vaginal | 10/56 (18) | 2/79 (3) | 15 (5 to 26) | .004 | |
| Any Grade of Intraventricular Hemorrhage, No./Total No. (%) | |||||
| Overall | 57/236 (24) | 50/238 (21) | 3 (−4 to 11) | .41 | |
| By gestational age at birth strata | |||||
| 23 wk 0 d through 27 wk 6 d | 34/93 (37) | 31/89 (35) | 2 (−12 to 16) | .81 | .67 |
| 28 wk 0 d through 31 wk 6 d | 23/143 (16) | 19/149 (13) | 3 (−5 to 11) | .42 | |
| By mode of delivery subgroups | |||||
| Cesarean | 33/180 (18) | 25/159 (16) | 3 (−5 to 11) | .52 | .52 |
| Vaginal | 24/56 (43) | 25/79 (32) | 11 (−5 to 28) | .18 | |
| Hemoglobin Level at a Mean of 4 (SD, 2) h of Life, Mean (SD), g/dL | |||||
| Overall | 16.5 (3.1) | 16.4 (2.7) | 0.06 (−0.52 to 0.65) | .83 | |
| By gestational age at birth strata | |||||
| 23 wk 0 d through 27 wk 6 d | 15.0 (2.8) | 14.9 (2.4) | 0.10 (−0.69 to 0.90) | .80 | .88 |
| 28 wk 0 d through 31 wk 6 d | 17.6 (2.9) | 17.4 (2.5) | 0.18 (−0.53 to 0.90) | .62 | |
| By mode of delivery subgroups | |||||
| Cesarean | 16.7 (3.0) | 16.2 (2.6) | 0.54 (−0.12 to 1.19) | .11 | .007 |
| Vaginal | 15.6 (3.1) | 16.9 (3.1) | −1.26 (−2.46 to −0.05) | .04 | |
| Hematocrit Level at a Mean of 4 (SD, 2) h of Life, Mean (SD), % | |||||
| Overall | 48.6 (8.2) | 48.6 (7.9) | 0.05 (−1.55 to 1.64) | .95 | |
| By gestational age at birth strata | |||||
| 23 wk 0 d through 27 wk 6 d | 45.1 (8.0) | 44.5 (6.7) | 0.63 (−1.67 to 2.93) | .59 | .66 |
| 28 wk 0 d through 31 wk 6 d | 51.2 (7.4) | 51.3 (7.4) | −0.04 (−1.95 to 1.88) | .97 | |
| By mode of delivery subgroups | |||||
| Cesarean | 49.1 (8.1) | 48.0 (7.5) | 1.11 (−0.71 to 2.93) | .23 | .03 |
| Vaginal | 47.0 (8.5) | 49.9 (8.5) | −2.89 (−6.20 to 0.42) | .09 | |
a
Tests the null hypothesis that the risk difference within each subgroup is equal to 0.
b
Tests the null hypothesis that the treatment group effect on the outcome is the same for each gestational age at birth strata or mode of delivery subgroup. For binary outcomes, such as any grade of intraventricular hemorrhage, the Breslow-Day test for the homogeneity of odds ratio was used. For continuous outcomes, such as hemoglobin level, linear regression including an interaction term was used.