| Total mother–child pairs | Singleton pairs | Twin pairs | ||||||
---|---|---|---|---|---|---|---|---|---|
 | Unexposed group | Betamethasone group | p | Unexposed group | Betamethasone group | p | Unexposed group | Betamethasone group | p |
n | 3596 | 745 | Â | 2678 | 631 | Â | 918 | 114 | Â |
Neonatal outcomes | |||||||||
Respiratory complications (%) | 395 (11.0) | 98 (13.2) | 0.102 | 281 (10.5) | 87 (13.8) | 0.022 | 114 (12.4) | 11 (9.6) | 0.482 |
Hypoglycemia (%) | 621 (17.3) | 154 (20.7) | 0.031 | 444 (16.6) | 130 (20.6) | 0.019 | 177 (19.3) | 24 (21.1) | 0.745 |
Maternal Characteristics | |||||||||
Age at delivery (mean (SD)) | 33.18 (6.16) | 32.63 (6.11) | 0.029 | 32.67 (6.08) | 32.55 (6.13) | 0.655 | 34.65 (6.15) | 33.11 (6.03) | 0.011 |
Race/ethnicity (%) |  |  |  < 0.001 |  |  |  < 0.001 |  |  |  < 0.001 |
 African-American | 413 (11.5) | 121 (16.2) |  | 345 (12.9) | 101 (16.0) |  | 68 (7.4) | 20 (17.5) |  |
 Asian | 261 (7.3) | 53 (7.1) |  | 187 (7.0) | 45 (7.1) |  | 74 (8.1) | 8 (7.0) |  |
 Caucasian/White | 2089 (58.1) | 339 (45.5) |  | 1451 (54.2) | 279 (44.2) |  | 638 (69.5) | 60 (52.6) |  |
 Hispanic/Latino | 558 (15.5) | 160 (21.5) |  | 484 (18.1) | 144 (22.8) |  | 74 (8.1) | 16 (14.0) |  |
 Other | 231 (6.4) | 60 (8.1) |  | 187 (7.0) | 50 (7.9) |  | 44 (4.8) | 10 (8.8) |  |
 Unknown | 44 (1.2) | 12 (1.6) |  | 24 (0.9) | 12 (1.9) |  | 20 (2.2) | 0 (0.0) |  |
Private insurance (%) | 2570 (71.5) | 458 (61.5) |  < 0.001 | 1770 (66.1) | 380 (60.2) | 0.006 | 800 (87.1) | 78 (68.4) |  < 0.001 |
BMI at delivery (mean (SD)) | 29.99 (5.90) | 30.14 (5.94) | 0.546 | 29.84 (6.21) | 30.01 (6.07) | 0.535 | 30.45 (4.85) | 30.85 (5.07) | 0.403 |
Gestational age (weeks) (mean (SD)) | 36.55 (0.68) | 36.31 (0.72) |  < 0.001 | 36.63 (0.63) | 36.35 (0.70) |  < 0.001 | 36.34 (0.77) | 36.05 (0.79) |  < 0.001 |
Cesarean delivery (%) | 2031 (56.5) | 439 (58.9) | 0.235 | 1261 (47.1) | 345 (54.7) | 0.001 | 770 (83.9) | 94 (82.5) | 0.8 |
Preeclampsia (%) | 169 (4.7) | 31 (4.2) | 0.588 | 123 (4.6) | 23 (3.6) | 0.35 | 46 (5.0) | 8 (7.0) | 0.494 |
GDM medication (%) | 733 (20.4) | 185 (24.8) | 0.008 | 639 (23.9) | 163 (25.8) | 0.323 | 94 (10.2) | 22 (19.3) | 0.006 |
Gestational Weeks (%) |  |  |  < 0.001 |  |  |  < 0.001 |  |  |  < 0.001 |
 34 | 393 (10.9) | 116 (15.6) |  | 221 (8.3) | 84 (13.3) |  | 172 (18.7) | 32 (28.1) |  |
 35 | 817 (22.7) | 284 (38.1) |  | 555 (20.7) | 240 (38.0) |  | 262 (28.5) | 44 (38.6) |  |
 36 | 2386 (66.4) | 345 (46.3) |  | 1902 (71.0) | 307 (48.7) |  | 484 (52.7) | 38 (33.3) |  |
Neonate covariates | |||||||||
Birth weight (mean (SD)) | 2.57 (0.43) | 2.49 (0.40) |  < 0.001 | 2.67 (0.41) | 2.54 (0.40) |  < 0.001 | 2.27 (0.33) | 2.22 (0.30) | 0.133 |
bBirth weight below 10th percentile | 304 (8.5) | 97 (13.0) |  < 0.001 | 143 (5.3) | 70 (11.1) |  < 0.001 | 161 (17.5) | 27 (23.7) | 0.14 |
cBirth weight below 3rd percentile | 132 (3.7) | 21 (2.8) | 0.29 | 53 (2.0) | 12 (1.9) | 1.00 | 79 (8.6) | 9 (7.9) | 0.937 |
Newborn sex = Male (%) | 1903 (52.9) | 396 (53.2) | 0.939 | 1426 (53.2) | 339 (53.7) | 0.864 | 477 (52.0) | 57 (50.0) | 0.767 |
Private insurance (%) | 2488 (69.2) | 434 (58.3) |  < 0.001 | 1714 (64.0) | 360 (57.1) | 0.001 | 774 (84.3) | 74 (64.9) |  < 0.001 |
Apgar score (mean (SD)) | 8.94 (0.34) | 8.88 (0.48) |  < 0.001 | 8.94 (0.36) | 8.88 (0.48) | 0.001 | 8.94 (0.29) | 8.88 (0.42) | 0.045 |
Apgar < 7 (%) | 13 (0.4) | 6 (0.8) | 0.172 | 13 (0.5) | 5 (0.8) | 0.521 | 0 (0.0) | 1 (0.9) | 0.214 |
NICU admission (%) | 455 (12.7) | 148 (19.9) |  < 0.001 | 302 (11.3) | 122 (19.3) |  < 0.001 | 153 (16.7) | 26 (22.8) | 0.133 |
Year of delivery (%) |  |  |  < 0.001 |  |  |  < 0.001 |  |  |  < 0.001 |
 2012 | 556 (15.5) | 12 (1.6) |  | 410 (15.3) | 8 (1.3) |  | 146 (15.9) | 4 (3.5) |  |
 2013 | 587 (16.3) | 19 (2.6) |  | 427 (15.9) | 15 (2.4) |  | 160 (17.4) | 4 (3.5) |  |
 2014 | 618 (17.2) | 22 (3.0) |  | 460 (17.2) | 16 (2.5) |  | 158 (17.2) | 6 (5.3) |  |
 2015 | 640 (17.8) | 20 (2.7) |  | 478 (17.8) | 20 (3.2) |  | 162 (17.6) | 0 (0.0) |  |
 2016 | 475 (13.2) | 200 (26.8) |  | 351 (13.1) | 164 (26.0) |  | 124 (13.5) | 36 (31.6) |  |
 2017 | 508 (14.1) | 237 (31.8) |  | 406 (15.2) | 199 (31.5) |  | 102 (11.1) | 38 (33.3) |  |
 2018 | 212 (5.9) | 235 (31.5) |  | 146 (5.5) | 209 (33.1) |  | 66 (7.2) | 26 (22.8) |  |