TABLE 1.
Characteristics of Infants Born at 22 to 28 Weeks’ GA in NRN Centers 2006–2011 by Maternal IDDM and Timing of Maternal Insulin Use
| Characteristica | IBP, n = 312 | IDP, n = 195 | No IDDM, n = 1 0245 |
|---|---|---|---|
| Maternal age, y | |||
| Mean (SD) | 30 (5.8)*IDP,**No IDDM | 31 (6.0)**No IDDM | 27 (6.5) |
| Category, n (%) | |||
| <25 | 66 (21)*IDP,**No IDDM | 29 (15)**No IDDM | 3908 (38) |
| 25–29 | 80 (26) | 52 (27) | 2641 (26) |
| 30–34 | 96 (31) | 58 (30) | 2265 (22) |
| 35–39 | 56 (18) | 33 (17) | 1115 (11) |
| ≥40 | 14 (4) | 23 (12) | 315 (3) |
| Maternal education, n (%) | n = 190 | n = 138 | n = 7035 |
| Less than high school degree | 42 (22)***IDP,***No IDDM | 34 (25) | 1826 (26) |
| High school degree | 63 (33) | 32 (23) | 2022 (29) |
| Partial college | 55 (29) | 31 (22) | 1508 (21) |
| College degree or more | 30 (16) | 41 (30) | 1679 (24) |
| Maternal race/ethnicity, n (%) | |||
| Black | 147 (47)**IDP,***No IDDM | 59 (30)**No IDDM | 3821 (37) |
| White | 101 (32) | 79 (41) | 4077 (40) |
| Hispanic | 50 (16) | 33 (17) | 1824 (18) |
| Other | 13 (4) | 24 (12) | 491 (5) |
| ≥1 prenatal visit, n (%) | 306 (98)***No IDDM | 194 (99)**No IDDM | 9679 (95) |
| Maternal HT, n (%) | 183 (59)**IDP,**No IDDM | 76 (39)**No IDDM | 2340 (23) |
| Maternal HT existing before pregnancy or chronic, n (%) | 127 (41)***IDP,**No IDDM | 53 (27)**No IDDM | 937 (9) |
| Maternal HT not existing before pregnancy, n (%) | 53 (17)*No IDDM | 23 (12) | 1302 (13) |
| Maternal antenatal steroids, n (%) | 246 (79)*IDP | 171 (88)*No IDDM | 8444 (83) |
| Cesarean delivery, n (%) | 218 (70)***No IDDM | 131 (67) | 6226 (61) |
| Multiple births, n (%) | 67 (21)*IDP | 60 (31) | 2615 (26) |
| GA, wk | |||
| Mean (SD) | 26.0 (1.6)***No IDDM | 26.3 (1.7)**No IDDM | 25.7 (1.8) |
| Category, n (%) | |||
| 22 | 7 (2)*IDP,*No IDDM | 5 (3)**No IDDM | 450 (4) |
| 23 | 14 (4) | 9 (5) | 950 (9) |
| 24 | 46 (15) | 22 (11) | 1420 (14) |
| 25 | 52 (17) | 27 (14) | 1594 (16) |
| 26 | 47 (15) | 26 (13) | 1696 (17) |
| 27 | 77 (25) | 42 (22) | 2001 (20) |
| 28 | 69 (22) | 64 (33) | 2134 (21) |
| Birth wt, g | |||
| Mean (SD) | 841 (240)***IDP | 903 (262)**No IDDM | 838 (247) |
| Category, n (%) | |||
| <401 | 4 (1)*IDP | 2 (1)**No IDDM | 114 (1) |
| 401–1000 | 234 (75) | 120 (62) | 7458 (73) |
| 1001–1500 | 74 (24) | 73 (37) | 2620 (26) |
| >1500 | — | — | 38 (<1) |
| Length at birth, cm | n = 291 | n = 180 | n = 9424 |
| Mean (SD) | 33.4 (3.1)**IDP | 34.6 (3.3)**No IDDM | 33.6 (3.4) |
| Head circumference at birth, cm | n = 285 | n = 182 | n = 9276 |
| Mean (SD) | 23.7 (2.1)***IDP | 24.2 (2.1)***No IDDM | 23.7 (2.1) |
| Ponderal index (g/cm3) | n = 285 | n = 178 | n = 9236 |
| Mean (SD) | 2.26 (0.30) | 2.22 (0.28) | 2.22 (0.29) |
| Birth measures (23–28 wk)b | |||
| z score, mean (SD)c | |||
| Weight | −0.20 (1.17) | −0.01 (1.16) | −0.10 (1.10) |
| Length | −0.31 (1.08)***IDP,***No IDDM | −0.01 (1.09) | −0.12 (1.10) |
| Head circumference | −0.33 (1.13)*IDP,**No IDDM | −0.08 (1.04) | −0.10 (1.08) |
| Head circumference z score, n (%) | |||
| Less than –2 | 21 (7)**No IDDM | 7 (4) | 388 (4) |
| Less than –2 to less than –1 | 52 (18) | 27 (15) | 1287 (14) |
| Greater than or equal to –1 | 211 (74) | 148 (81) | 7477 (82) |
| Percentiles, n (%) | |||
| Wt | |||
| Small for GA | 54 (18)*IDP | 23 (12) | 1361 (14) |
| Appropriate for GA | 222 (73) | 141 (74) | 7504 (77) |
| Large for GA | 29 (10) | 26 (14) | 917 (9) |
| Length | |||
| Small for GA | 50 (17)*IDP | 18 (10) | 1268 (14) |
| Appropriate for GA | 219 (76) | 143 (80) | 7159 (78) |
| Large for GA | 20 (7) | 18 (10) | 798 (9) |
| Head circumference | |||
| Small for GA | 47 (17)*No IDDM | 21 (12) | 1064 (12) |
| Appropriate for GA | 218 (77) | 144 (79) | 7318 (80) |
| Large for GA | 19 (7) | 17 (9) | 770 (8) |
| Male, n (%) | 147 (47) | 90 (46) | 5372 (52) |
| Apgar at 1 min ≤3, n (%) | 132 (42) | 79 (41) | 4642 (46) |
| Apgar at 5 min ≤3, n (%) | 47 (15) | 24 (12)*No IDDM | 1841 (18) |
| Delivery room interventions, n (%) | |||
| Oxygen | 294 (94) | 182 (93) | 9368 (92) |
| Bagging and mask | 218 (70) | 136 (70) | 7366 (72) |
| CPAP | 109 (35) | 81 (42) | 3646 (36) |
| Intubation | 199 (64) | 119 (61) | 6601 (64) |
| Chest compression | 23 (7) | 11 (6) | 852 (8) |
| Epinephrine | 18 (6) | 8 (4) | 475 (5) |
| Ventilator support, n (%)d | 263 (84) | 153 (78) | 8279 (81) |
| Surfactant therapy, n (%) | 252 (81)*No IDDM | 148 (76) | 7641 (75) |
| Major birth defect, n (%) | 15 (5) | 4 (2) | 373 (4) |
CPAP, continuous positive airway pressure; HT, hypertension.
Information was missing in the groups shown for maternal age, 1 infant; maternal education, 3389 infants; maternal race/ethnicity, 33 infants; prenatal visits, 5 infants; maternal HT, 2 infants; maternal HT before or not before pregnancy, 106 infants; maternal antenatal steroids, 30 infants; birth weight, 15 infants; length at birth, 857 infants; head circumference at birth, 1009 infants; ponderal index, 1053 infants; Apgar at 1 min, 92 infants; Apgar at 5 min, 87 infants; mode of delivery, 5 infants; delivery room oxygen, CPAP, intubation, chest compression, 7 infants; delivery room bagging and mask, 9 infants; delivery room epinephrine, 8 infants; ventilator support, 4 infants; surfactant therapy, 2 infants.
z scores and percentiles from Olsen.14 Small for GA was defined as weight, length, or head circumference <10th percentile and large for GA >90th percentile. The Olsen measures are available for male and female infants born at GA 23–41 wk. Therefore, 462 infants born at 22 wk GA could not be included. In the group of 10 290 infants born at GA 23–28 wk, birth weight was missing/excluded for 13 infants, length for 597 infants, and head circumference for 672.
After adjustment for study center, GA, male gender, antenatal steroid use, maternal age, and maternal race/ethnicity, results for comparisons of z score means were similar to unadjusted results with 1 exception. The mean z score for head circumference was not significantly different for infants whose mothers used insulin before pregnancy versus those whose mothers started insulin during pregnancy, adjusted P = .054 (unadjusted P = .017).
Ventilator support was defined as use of high frequency or conventional ventilation for infants who survived >12 h. For infants born in 2006–2010 who died ≤12 h, all forms of support with a ventilator after initial resuscitation were included. Beginning in 2011, respiratory support recorded for infants who died ≤12 h was defined as any ventilator pressure support and/or supplemental oxygen delivery by any method. In the subset of 9585 infants who survived >12 h, the percent who received mechanical ventilation did not vary significantly between groups (IBP: 88%, IDP: 83%, no IDDM: 88%; P = .17).
P ≤ .05,
P ≤ .001 by t test (means for maternal age, GA, birth weight, length, head circumference, ponderal index, z score), the row mean score χ2 test with modified ridit scores specified (categorical maternal age, GA, birth weight, head circumference z score, and percentiles), the general association χ2 test, or Fisher’s exact test. Pairwise comparisons were performed between infants with maternal IBP versus infants with maternal IDP and infants with no maternal IDDM, and between infants with maternal IDP versus infants with no maternal IDDM. For each significant result, the comparison group is indicated.
P ≤ .01,