Table 1.
Maternal characteristics among pregnancies with and without AKI-D
| Characteristic | AKI-D n=188 | No AKI-D n=1,918,601 | P Valuea |
|---|---|---|---|
| Unique mothers, n | 188 | 1,204,609 | |
| Age at delivery (years), median (IQR) | 32 (25–35) | 30 (25–34) | 0.03 |
| Age category at delivery (years), n (%) | 0.01 | ||
| <20 | 11 (5.9) | 78,037 (4.1) | |
| 20–29 | 61 (32.4) | 823,665 (42.9) | |
| 30–39 | 106 (56.4) | 956,009 (49.8) | |
| ≥40 | 10 (5.3) | 60,890 (3.2) | |
| Neighborhood income quintile, n (%) | 0.04 | ||
| 1–2 (lowest) | 95 (50.5) | 818,899 (42.7) | |
| 3 (middle) | 26 (13.8) | 385,375 (20.1) | |
| 4–5 (highest) | 66 (35.1) | 704,477 (36.7) | |
| Rural residence, n (%) | 18 (9.6) | 202,373 (10.5) | 0.66 |
| Number of previous pregnanciesb | 0.49 | ||
| 0 | 104 (55.3) | 990,884 (51.6) | |
| 1 | 57 (30.3) | 659,676 (34.4) | |
| ≥2 | 27 (14.4) | 268,041 (14.0) | |
| Time since previous pregnancy (years), median (IQR) | 0 (0–3) | 0 (0–3) | 0.55 |
| Recorded preexisting medical conditionsc n (%) | |||
| Hypertension | 10 (5.3) | 25,439 (1.3) | <0.001 |
| Diabetes mellitus | ≤5 (≤2.7) | 14,935 (0.8) | 0.70 |
| Chronic kidney disease | 8 (4.3) | 4,568 (0.2) | <0.001 |
| Systemic lupus erythematosis | ≤5 (≤2.7) | 627 (0.03) | <0.001 |
| Thrombotic microangiopathy treated with plasma exchange | 0 (0.0) | 24 (0.001) | 0.96 |
| Any of the above preexisting medical conditions | 21 (11.2) | 102,026 (5.3) | <0.001 |
| Pre-pregnancy physician consultationc n (%) | |||
| General practitioner/family physician | 178 (94.7) | 1,814,275 (94.6) | 0.94 |
| Internal medicine specialist | 40 (21.3) | 301,323 (15.7) | 0.04 |
| Nephrologist | 11 (5.9) | 9,080 (0.5) | <0.001 |
| Number of prenatal physician visitsd median (IQR) | 10 (6.5–12) | 10 (8–12) | 0.02 |
| Number of ultrasonographic examinationsd median (IQR) | 2 (0–4) | 2 (0–4) | 0.53 |
| Use of assisted reproductive technologiese n (%) | 6 (3.2) | 37,471 (2.0) | 0.22 |
To comply with privacy regulations for minimizing the chance of identification of a study participant, numbers of participants are suppressed in the case of five or fewer participants (reported as ≤5).
P values were derived from two-sample t-tests when comparing continuous variables and chi-squared tests when comparing categorical variables.
Information on previous pregnancies was available since 1991 and included all pregnancies in Ontario resulting in livebirth or stillbirth after 20 weeks’ gestation.
Information on preexisting medical conditions and consultations was ascertained from administrative database codes in the 5 years prior to pregnancy.
Information on prenatal visits and ultrasonographic examinations was ascertained from administrative database codes during pregnancy.
Use of assisted reproductive technologies was ascertained from administrative database codes in the year prior to conception and during pregnancy and the postpartum period, and includes tuboplasty after previous sterilization, artificial insemination, ovarian hyperstimulation, in vitro fertilization, and other unspecified fertilization methods.