Table 1. Prevalence of Risk Factors and Gestational Hypertension and Eclampsia Outcomes.
| Risk Factors | Pregnancies with risk factors, No. | gHTN and eclampsia, No. | gHTN and eclampsia, % | NNT, relative risk (95% CI)c | |
|---|---|---|---|---|---|
| Ratea | Proportionb | ||||
| Total pregnancies | 3 695 019 | 300 080 | 8.1 | 100.0 | 78 (47-233) |
| None | 528 778 | 23 188 | 4.4 | 7.7 | 152 (81-456) |
| ≥1 High-risk factors | 169 540 | 25 348 | 15.0 | 8.4 | 45 (27-134) |
| Any 1 moderate-risk factors | 1 303 890 | 81 383 | 6.3 | 27.0 | 107 (64-320) |
| Single moderate-risk factors | |||||
| Low socioeconomic status | 465 804 | 18 441 | 4.0 | 6.1 | 168 (101-505) |
| Nulliparous | 386 523 | 29 481 | 7.6 | 9.8 | 87 (52-262) |
| Age ≥ 35 y | 204 718 | 9477 | 4.6 | 3.1 | 144 (86-432) |
| BMI ≥ 30 | 173 810 | 19 265 | 11.0 | 6.4 | 60 (36-180) |
| African American race | 40 090 | 2207 | 5.5 | 0.7 | 121 (73-363) |
| Prior preterm birth | 18 268 | 1492 | 8.2 | 0.5 | 82 (49-245) |
| ≥ 10 y since last birth | 9679 | 560 | 5.9 | 0.2 | 115 (69-346) |
| In vitro conceptiond | 4998 | 457 | 9.1 | 0.2 | 73 (52-262) |
| Moderate-risk factors combined, No. | |||||
| 2 | 1 109 585 | 98 292 | 8.9 | 32.7 | 75 (45-226) |
| 3 | 474 696 | 55 747 | 11.7 | 18.5 | 57 (34-170) |
| 4 | 99 372 | 15 297 | 15.4 | 5.1 | 43 (26-130) |
| 5 | 8792 | 1615 | 18.4 | 0.5 | 36 (22-109) |
| 6 | 367 | 78 | 21.3 | 0.02 | 31 (19-34) |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); gHTN, gestational hypertension; NNT, number needed to treat; USPSTF, United States Preventive Services Task Force.
a
Among those with given risk factor or number of risk factors.
b
Among all cases of gestational hypertension or eclampsia.
c
Assumes 0.85 (95% CI, 0.75-0.95) relative risk for gestational hypertension, which is equivalent to USPSTF estimate for preeclampsia.
d
Newly added to the 2021 USPSTF Aspirin Use to Prevent Preeclampsia Guidelines.