Table 1.
Characteristics of the POP study cohort in the metabolomics analysis of pre-eclampsia
| Characteristic | PE term (N = 165) | PE pre-term (N = 29) | Controls without pre-term PE (N = 323) |
|---|---|---|---|
| Maternal characteristics | |||
| Age, years | 30 (26 to 34) | 28 (23 to 33) | 30 (27 to 33) |
| Age stopped FTE ≥21 years | 75 (45%) | 8 (28%) | 177 (55%) |
| Missing | 5 (3%) | 1 (3%) | 2 (1%) |
| Height, cm | 165 (160 to 168) | 163 (158 to 166) | 165 (161 to 169) |
| BMI, kg/m2 | 26 (23 to 32) | 28 (26 to 30) | 24 (22 to 28) |
| Smoker | 6 (4%) | 1 (3%) | 15 (5%) |
| Any alcohol consumption | 7 (4%) | 0 (0%) | 12 (4%) |
| Deprivation, score | 8.91 (5.56 to 13.59) | 9.66 (5.68 to 11.85) | 8.53 (5.95 to 14.18) |
| Deprivation, rank | 25246 (19634 to 29324) | 24266 (21549 to 29179) | 25727 (19039 to 28872) |
| Deprivation rank quintile | |||
| 1 (most deprived) | 0 (0%) | 0 (0%) | 0 (0%) |
| 2 | 13 (8%) | 1 (3%) | 20 (6%) |
| 3 | 26 (16%) | 5 (17%) | 64 (20%) |
| 4 | 45 (27%) | 13 (45%) | 79 (24%) |
| 5 (least deprived) | 73 (44%) | 10 (34%) | 148 (46%) |
| Missing | 8 (5%) | 0 (0%) | 12 (4%) |
| White ethnicity | 157 (95%) | 26 (90%) | 302 (94%) |
| Missing | 1 (1%) | 1 (4%) | 6 (2%) |
| Married | 105 (64%) | 22 (76%) | 232 (72%) |
| Diabetes | |||
| Type 1 or type 2 DM | 2 (1%) | 3 (10%) | 0 (0%) |
| Gestational DM | 11 (7%) | 1 (3%) | 11 (3%) |
| Essential HT | 35 (21%) | 12 (41%) | 9 (3%) |
| Pre-existing renal disease | 3 (2%) | 1 (3%) | 2 (1%) |
| Birth outcomes | |||
| Birthweight, g | 3390 (3050 to 3760) | 2130 (1600 to 2580) | 3445 (3100 to 3775) |
| Birthweight, centile | 45 (24 to 67) | 17 (8 to 44) | 47 (23 to 68) |
| Gestational age, weeks | 39.9 (38.6 to 40.9) | 35.3 (33.3 to 36.3) | 40.3 (39.3 to 41.3) |
| Female fetal sex | 72 (44%) | 16 (55%) | 165 (51%) |
| Induction of labour | 106 (64%) | 7 (24%) | 114 (35%) |
| Mode of delivery | |||
| Spontaneous vaginal | 36 (22%) | 7 (24%) | 161 (50%) |
| Assisted vaginal | 51 (31%) | 0 (0%) | 68 (21%) |
| Intra-partum caesarean | 55 (33%) | 3 (10%) | 59 (18%) |
| Pre-labour caesarean | 22 (13%) | 19 (66%) | 33 (10%) |
| Missing | 1 (1%) | 0 (0%) | 2 (1%) |
In total, 4212 women completed the POP study. After the exclusion of miscarriages, fetal deaths prior to 23 wkGA and terminations (total n = 29) and women who did not have any blood samples available (n = 6), 4177 women remained in the cohort and the random sub-cohort (n = 325) was selected from this population. Data are expressed as median (IQR) or n (%) as appropriate. For fields where there is no category labelled ‘missing’, data were 100% complete.
Maternal age was defined as age at recruitment. All other maternal characteristics were defined by self-report at the 20-wkGA questionnaire, from examination of the clinical case record or linkage to the hospital’s electronic databases. The weight measurement used in the BMI calculation was made at the 12-wkGA visit. Socio-economic status was quantified using the Index of Multiple Deprivation (IMD) 2007,16 which is based on census data from the area of the mother’s postcode. Deprivation score is the combined sum of the weighted, exponentially transformed domain rank of the domain score and higher values indicate more deprivation. Conversely, the most deprived area has the lowest rank (= 1) and the least deprived area has the highest rank (= 32 482). A national reference distribution from 201017 has been used to analyse the rank in quintiles (1 = most deprived, 5 = least deprived), enabling a comparison with the Born in Bradford study. Pre-eclampsia was defined on the basis of the 2013 ACOG criteria. FTE, full-time education; BMI, body mass index; DM, diabetes mellitus; PE, pre-eclampsia; HT, hypertension.