Characteristics of women in development and internal-external cross validation cohorts: UK (Allen et al, 2017),32 Australia (Rumbold et al, 2006),31 Norway (STORK Groruddalen research programme, 2010)33 and US (National Institute of Child Health and Human Development (NICHD), 2018)34 cohorts, and pooled data
| Characteristics | Allen et al, 2017 | Rumbold et al, 2006 | STORK Groruddalen, 2010 | NICHD, 2018 | Pooled data | |||||
| Values | Missing values | Values | Missing values | Values | Missing values | Values | Missing values | Values | Missing values | |
| No of pregnancies | 1045 | — | 1877 | — | 823 | — | 233 483 | — | 237 228 | — |
| Median (IQR) gestational age at delivery (weeks) | 40.0 (39.3-40.6) | 1 (0.1) | 40.0 (39.0-41.0) | — | 40.0 (38.9-40.9) | 22 (2.7) | 39.0 (38.0-40.0) | 7929 (3.4) | 39.0 (38.0-40.0) | 7952 (3.4) |
| Median (IQR) maternal weight (kg) | 62.0 (55.0-69.0) | 5 (0.5) | 66.0 (58.5-76.0) | 103 (5.5) | 64.6 (56.9-72.9) | 421 (51.2) | 66.7 (57.6-80.3) | 31 314 (13.4) | 66.7 (57.6-80.0) | 31 843 (13.4) |
| Mean (SD) maternal height (cm) | 161.5 (13.3) | — | 165.3 (15.7) | 138 (7.4) | 163.6 (13.3) | — | 163.3 (6.6) | 37 567 (16.1) | 163.3 (8.0) | 37 705 (15.9) |
| Mean (SD) maternal age (years) | 29.9 (7.4) | 1 (0.1) | 26.4 (6.7) | — | 29.9 (6.7) | — | 27.7 (7.4) | 339 (0.1) | 27.7 (7.4) | 340 (0.1) |
| Nulliparous | 584 (55.9) | — | 1877 (100.0) | — | 381 (46.3) | — | 93 545 (40.1) | — | 96 387 (40.6) | — |
| Smoked during pregnancy | 38 (3.6) | — | 364 (19.4) | 39 (2.1) | 50 (6.1) | — | 15 547 (6.7) | — | 15 999 (6.7) | 39 (0.2) |
| Ethnic group | — | 2 (0.2) | 4 (0.2) | — | — | — | 9557 (4.1) | — | 9563 (4.0) | |
| White | 398 (38.1) | — | 1777 (94.7) | — | 379 (46.1) | 116 000 (49.7) | — | 118 554 (50.0) | — | |
| Black | 108 (10.3) | — | 3 (0.2) | — | 62 (7.5) | 52 518 (22.5) | — | 52 691 (22.2) | — | |
| South Asian | 495 (47.4) | — | 1 (0.1) | — | 200 (24.3) | 9487 (4.1) | — | 10 183 (4.3) | — | |
| Hispanic | — | — | 1 (0.1) | — | 12 (1.5) | 40 409 (17.3) | — | 40 422 (17.0) | — | |
| Mixed | 12 (1.1) | — | 4 (0.2) | — | — | 347 (0.1) | — | 363 (0.2) | — | |
| Other | 30 (2.9) | — | 87 (4.6) | — | 170 (20.7) | 5165 (2.2) | — | 5452 (2.3) | — | |
| History of hypertension | 10 (1.0) | — | 9 (0.5) | — | 13 (1.6) | — | 4589 (2.0) | — | 4621 (1.9) | — |
| History of diabetes | 11 (1.1) | — | 8 (0.4) | — | — | — | 4946 (2.1) | 7878 (3.4) | 4965 (2.1) | 7878 (3.3) |
| Assisted conception | 23 (2.2) | — | 50 (2.7) | 39 (2.1) | 13 (1.58) | — | 1472 (0.6) | 109 799 (47.0) | 3354 (1.4) | 109 838 (46.3) |
| Any previous pre-eclampsia | 17 (1.6) | — | — | — | — | — | 10 131 (4.3) | 31 545 (13.5) | 10 148 (4.3) | 31 545 (13.3) |
| Any previous stillbirth | 12 (1.1) | — | — | — | 81 | — | 2029 (0.9) | 96 159 (41.2) | 2049 (0.9) | 96 159 (40.5) |
| Any previous baby born small for gestational age | 67 (6.4) | — | — | — | 31 (3.8) | — | 2857 (1.2) | 9640 (4.1) | 2955 (1.2) | 9640 (4.1) |
| Mean (SD) birth weight (g) | 3298.3 (524.5) | 4 (0.4) | 3382.0 (608.9) | 6 (0.3) | 3418.3 (570.1) | 38 (4.6) | 3199.8 (644.1) | 2674 (1.1) | 3202.0 (643.4) | 2722 (1.1) |
Data are number (%) unless indicated otherwise.
Missing values are number (%).
IQR, interquartile range; SD, standard deviation.