Table 1.
Baseline and ultrasound characteristics of participants in studies that contributed to the IPD
| Baseline characteristics | Number of studies | Number of women | Mean (SD) or n (%)* |
|---|---|---|---|
| Age (years) | 17 | 21 661 | 30.4 (6.1) |
| Body mass index (kg/m2) | 14 | 19 239 | 25.5 (6.2) |
| Ethnicity | |||
| Caucasian | 12 | 18 274 | 10 842 (59.3%) |
| Black | 12 | 18 274 | 2394 (13.1%) |
| Asian | 12 | 18 274 | 3116 (17.1%) |
| Other | 12 | 18 274 | 1992 (10.5%) |
| Smoker | 13 | 19 870 | 2143 (10.8%) |
| Nulliparous | 16 | 21 318 | 10 864 (51.0%) |
| Pre‐eclampsia | 7 | 4085 | 376 (9.2%) |
| Hypertension | 7 | 7419 | 729 (9.8%) |
| Maternal diabetes | 9 | 7827 | 1916 (24.5%) |
| Gestational age at ultrasound (weeks) | 17 | 21 647 | 37.2 (3.4) |
| UA (pulsatility index) | 17 | 21 661 | 0.91 (0.34) |
| MCA (pulsatility index) | 17 | 21 661 | 1.54 (0.41) |
| Cerebroplacental ratio | 17 | 21 661 | 1.80 (0.56) |
| EFW (g) | 8 | 6556 | 2639.0 (666.2) |
| EFW centile | 8 | 6556 | 54.5 (29.9) |
*
Percentage of number of cases.