Table 1.
Characteristics of the included studies and their participants
| Characteristics | <20 weeks gestation (N=23 studies) |
|---|---|
| Studies | |
| Type | |
| Observational retrospective controlled | 12 (52) |
| Observational prospective controlled | 2 (9) |
| Secondary analysis of randomized controlled trial | 9 (39) |
| Center status | |
| Single center | 11 (48) |
| Multiple centers <5 | 2 (10) |
| Multiple centers ≥5 | 11 (48) |
| Low- and middle-income country | 4 (17) |
| Funding reported | |
| None | 2 (10) |
| Not reported | 6 (29) |
| Externally funding reported | 13 (62) |
| Full publication | 23 (100) |
| Includes unpublished data | 4 (17) |
| QUADAS-2 overall risk of bias | |
| High risk | 15 (65) |
| Low risk | 4 (17) |
| Unclear | 4 (17) |
| Participants | |
| Total | 734,377 |
| Number per study | 9869 (2720–19,368) |
| Gestational age at study enrolmenta | |
| 1st trimester | 5 (22) |
| 2nd trimester | 18 (78) |
| 3rd trimester | Not applicable |
| Inclusion criteria | |
| Intention to enroll a low-risk cohort | 8 (35%) |
| Exclusion criteria | |
| Multiple pregnancy | 19 (83) |
| Chronic hypertension | 11 (48) |
| Diabetes mellitus | 5 (22) |
| Chronic kidney disease | 5 (22) |
| Systemic lupus erythematosus | 3 (13) |
| Demographics | |
| Maternal age reported | 20 (87) |
| Age (y), median of reported mean or median (IQR) | 29.6 (26.1–30.5) (20 studies) |
| Number of studies with ≥50% women aged ≥35 y | 2 (12) (9 studies) |
| Nulliparity reported | 21 (91) |
| Nulliparity, median % (IQR) | 43.2 (36.2–74.4) |
| Number of studies with ≥50% nulliparous participants | 9 (39) |
| BMI (kg/m2) reportedb | 20 (87) |
| BMI (kg/m2) (median of mean or median (IQR)) | 25.1 (23.4–26.2) (15 studies) |
| Overweight,c median % (IQR) | 11.5 (9.5–26.3) (8 studies) |
| Ethnicity reported, median % (IQR) | 19 (83) |
| Non-Hispanic White | 36.3 (25.0–50.7) (11 studies) |
| Non-Hispanic Black | 19 (10.6–44.0) (11 studies) |
| Hispanic | 16.4 (1.5–37.5) (11 studies) |
| Asiand | 73.4 (13.6–99.0) (14 studies) |
| Other (median % (IQR) women) | 2.9 (1.7–8.4) (8 studies) |
| N studies without predominance of any one ethnicity | 3/19 (16) |
| Aspirin use for preeclampsia prevention reportede | 10 (43) |
| Aspirin use (median % (IQR) women) | 12.7 (5.8–40.3) (10 studies) |
| BP measurementsf | |
| Nature of BP measurements used to define ACC-AHA level | |
| One measurement | 16 (70) |
| Multiple––at least 2 consecutive measurements | 4 (17) |
| Average of multiple measurements | 5 (22) |
| Normal BP compared with: | |
| Elevated BP | 9 (39) |
| Stage 1 hypertension | 9 (39) |
| Stage 2 hypertension | 7 (30) |
| BP cutoffs examined as new thresholds for abnormal BP: | |
| sBP 120 mmHg (with dBP <80 mmHg) | 8 (35) |
| sBP 130 mmHg or dBP 80 mmHg | 13 (57) |
| sBP 140 mmHg or dBP 90 mmHg | 13 (57) |
| Results presented adjusted for baseline characteristics | 16 (70) |
Data are presented as number (percentage) of pregnancies and median (interquartile range) unless otherwise stated).
ACC-AHA, American College of Cardiology-American Heart Association; BMI, body mass index; BP, blood pressure; dBP, diastolic BP; IQR, interquartile range.
Slade. The diagnostic accuracy of American College of Cardiology-American Heart Association blood pressure categories for identification of women and babies at risk. Am J Obstet Gynecol 2023.
Not mutually exclusive
Institute of Medicine BMI criteria were used to define overweight (BMI, 25.0–29.9 kg/m2) and obesity (BMI, ≥30 kg/m2), unless ethnicity-refined norms were specified in the publication.11,34 BMI was recorded as a continuous value in 15 of 22 studies and as a cutoff for overweight or obesity in 8 of 22 studies with only 2 of 22 reporting both continuous and cutoff values
The definition of overweight was as defined by the study authors
Studies from China and Japan recorded as >90% Asian population without specific descriptors of study populations, because of low level of ethnic variation in these populations
Aspirin use was reported in studies that enrolled women at increased risk for preeclampsia
BP was categorized as normal (sBP <120 mmHg and dBP <80 mmHg), elevated BP (sBP 120–129 mmHg and dBP <80 mmHg), stage 1 hypertension (sBP 130–139 mmHg and/or dBP 80–89 mmHg), and stage 2 hypertension (sBP ≥140 mmHg and/or dBP ≥90 mmHg), which was also subdivided into nonsevere (sBP 140–159 mmHg and/or dBP 90–109 mmHg) and severe cases (sBP ≥160 mmHg and/or dBP ≥110 mmHg)2. A diagnosis of stage 2 hypertension was accepted when based on prescription of antihypertensive therapy (because there is no precedent for routine treatment of BP <140/90 mmHg).