Characteristics of pregnancies with measurement of serum creatinine within 10 weeks before conception
| Characteristic | Cohort or subcohort; no. (%) of pregnancies* | ||
|---|---|---|---|
| Overall n = 55 946 | With apparently healthy renal function n = 46 116 | With chronic kidney disease† n = 9830 | |
| Age at time of conception, yr, mean ± SD | 30.7 ± 5.1 | 30.7 ± 5.1 | 30.5 ± 5.4 |
| Maternal world region of origin | |||
| Asia | 10 982 (19.6) | 9252 (20.1) | 1730 (17.6) |
| Caribbean/Africa | 2542 (4.5) | 1936 (4.2) | 606 (6.2) |
| Hispanic America | 1520 (2.7) | 1256 (2.7) | 264 (2.7) |
| Other | 40 902 (73.1) | 33 672 (73.0) | 7230 (73.6) |
| Income quintile | |||
| Q1 (lowest) or missing | 12 014 (21.5) | 9628 (20.9) | 2386 (24.3) |
| Q2 | 11 225 (20.1) | 9240 (20.0) | 1985 (20.2) |
| Q3 | 11 306 (20.2) | 9311 (20.2) | 1995 (20.3) |
| Q4 | 12 455 (22.3) | 10 358 (22.5) | 2097 (21.3) |
| Q5 (highest) | 8946 (16.0) | 7579 (16.4) | 1367 (13.9) |
| Urban residence | 52 563 (94.0) | 43 292 (93.9) | 9271 (94.3) |
| Parity, median (IQR) | 1 (0–1) | 1 (0–1) | 1 (0–1) |
| Nulliparous | 25 563 (45.7) | 22 205 (48.2) | 3358 (34.2) |
| Prepregnancy weight, kg, mean ± SD‡ | 69.8 ± 17.9 | 69.2 ± 17.4 | 72.7 ± 19.7 |
| Medical comorbidities ≤ 4 yr before conception | |||
| Diabetes mellitus type 1 and type | 2 8695 (15.5) | 6456 (14.0) | 2239 (22.8) |
| Chronic hypertension | 7785 (13.9) | 5324 (11.5) | 2461 (25.0) |
| Illicit drug use or tobacco use | 3016 (5.4) | 2442 (5.3) | 574 (5.8) |
| Maternal conditions during index pregnancy | |||
| Hypertensive disorder of pregnancy | 3387 (6.1) | 2359 (5.1) | 1028 (10.5) |
| Gestational diabetes mellitus | 5225 (9.3) | 3713 (8.1) | 1512 (15.4) |
| Measured renal function before conception | |||
| Serum creatinine | |||
| Measured value, μmol/L, mean ± SD | 60.7 ± 10.4 | 60.4 ± 9.5 | 61.7 ± 14.1 |
| Measured value > 95th percentile (i.e., > 77 μmol/L) | 2831 (5.1) | 2105 (4.6) | 726 (7.0) |
| Measured value > 99th percentile (i.e., > 86 μmol/L) | 684 (1.2) | 413 (0.90) | 271 (2.8) |
| Baseline eGFR | |||
| Measured value, mL/min/1.73 m2, mean ± SD | 113.9 ± 13.8 | 114.0 ± 13.3 | 113.1 ± 15.8 |
| Measured value > 60 mL/min/1.73 m2 | 55 858 (99.9) | 46 116 (100.0) | 9742 (99.1) |
| Measured value < 5th percentile (i.e., < 88 mL/min/1.73 m2) | 2824 (5.0) | 2135 (4.6) | 689 (7.0) |
Note: eGFR = estimated glomerular filtration rate, IQR = interquartile range, SD = standard deviation.
↵* Except where indicated otherwise.
↵† Chronic kidney disease was defined as serum creatinine above the 95th percentile (i.e., > 77 μmol/L).
↵‡ Based on 20 161 pregnancies with known prepregnancy weight.