Objective
The purpose of this study was to compare maternal and neonatal outcomes of women with gestational hypertension (GHTN), mild chronic hypertension (CHTN), and mild preeclampsia at delivery.
Study Design
A multicenter database that contained 228,668 deliveries was used to extract data on gravid women with GHTN, preeclampsia, and CHTN and on women without hypertensive disease (control group). Univariate and multivariate logistic regression analyses were performed.
Results
There were 4918 women with GHTN, 5274 women with preeclampsia, 2531 women with CHTN, and 15,221 control subjects. Women with GHTN had the greatest risk for blood transfusion (adjusted odds ratio [aOR], 4.6; 95% confidence interval [CI], 3.4–6.3), intensive care unit admission (aOR, 25.7; 95% CI, 9.8–67.3), and lowest risk for stillbirth (aOR, 0.1; 95% CI, 0.04–0.4); women with preeclampsia had the greatest risk for postpartum hypertension (aOR, 9.6; 95% CI, 7.2–12.9). Neonates with GHTN had the greatest risk for ventilator requirements (aOR, 7.5; 95% CI, 4.6–12.4).
Conclusion
Women with gestational hypertension and their neonates had significant risks for morbidity, compared with women with mild chronic hypertension and those with mild preeclampsia.
Hypertension is one of the most common medical disorders in pregnancy and a major cause of maternal and perinatal morbidity and death. Approximately 70% of women who are diagnosed with hypertension during pregnancy will have gestational hypertension or preeclampsia, which complicates 6-8% of all pregnancies. Approximately 46% and 9.6% of women with gestational hypertension will progress to mild preeclampsia and severe preeclampsia, respectively.
Most gestational hypertensive and mild preeclamptic cases occur after 36 weeks gestation, and there is conflicting evidence regarding treatment of these women. It was previously thought that women with mild hypertensive disease that occurred at ≥37 weeks’ gestation have a pregnancy outcome similar to that found in normotensive women, and previous recommendations have included outpatient treatment in those who were compliant with induction of labor near term. However, it has been demonstrated recently that pregnant women with mild disease (gestational hypertension or mild preeclampsia) who were allocated to expectant monitoring experienced adverse maternal outcome in 44%, compared with 31%, allocated to induction of labor (relative risk, 0.71; 95% confidence interval [CI], 0.59–0.86; P < .0001). Thus, induction of labor now has been suggested for women with mild hypertensive disease who have achieved 37 weeks gestation. However, Koopmans et al did not separate gestational hypertension from mild preeclampsia, which made it unclear whether morbidities were similar and whether recommendations should be the same for both.
The objective of this study was to compare maternal and neonatal outcomes of women with gestational hypertension, mild chronic hypertension, and mild preeclampsia from a large, multicenter electronic database. Main maternal outcomes included intensive care unit (ICU) admission rate, the number of postpartum days in the hospital, cesarean delivery rate, stillbirth rate, and the amount of blood loss. Primary neonatal outcomes addressed included neonatal ICU (NICU) admissions, the number of NICU days, respiratory distress syndrome (RDS), ventilator use, presence of intrauterine growth restriction, and the number of neonatal deaths. Our hypothesis was that these outcomes will be similar among pregnant women with gestational hypertension and mild preeclampsia, but greater in pregnant women with chronic hypertension.
Materials and Methods
This is a retrospective cohort study from the Consortium on Safe Labor, which was a study sponsored by the Eunice Kennedy Shriver National Institute of Child Health and Human Development. The primary goal was to establish a comprehensive database from electronic medical records from multiple sites to characterize labor and delivery in a contemporary group of women who experienced current obstetric clinical practices. More detailed information regarding the Consortium on Safe Labor has been published. The electronic database contained 228,668 deliveries at >23 weeks’ gestation from 12 clinical centers and 19 hospitals that represented 9 American College of Obstetricians and Gynecologists districts between 2002 and 2008; most of the births (87%) occurred from 2005-2007 (which reflected the period when individual institutions initiated their electronic medical record systems). An in-house obstetrician was available 24 hours per day at 11 of the 12 participating sites. Participating institutions provided data on maternal demographics, medical history, reproductive and prenatal history, labor and delivery information, postpartum information, and newborn information. Data inquiries, cleaning, and logic checking were performed on the database. Validation studies were also performed to ensure that the electronic database was a reasonably accurate representation of the medical charts and noted to be highly consistent (97.3-99.7%). Institutional Review Board approval was obtained by all participating institutions.
For the cohort of interest, we included only the first pregnancy, within the timeframe of data collection, from each subject in the database to avoid intraperson correlation, which left 206,969 deliveries, including multiples. We included all pregnant women with hypertensive disease in pregnancy that met the definition for gestational hypertension, mild chronic hypertension, and mild preeclampsia at admission for delivery. All participating institutions used standard definitions to delineate the hypertensive diseases. Gestational hypertension was defined as an elevation in blood pressure (BP) ≥140 mm Hg systolic or ≥ 90 mm Hg diastolic without proteinuria that developed in a woman after 20 weeks of gestation. Chronic hypertension was defined as having a preexisting diagnosis of chronic hypertension or having a systolic BP ≥140 mm Hg or diastolic ≥90 mm Hg before 20 weeks of gestation; mild disease was defined as those women not taking antihypertensive medications on admission. Mild preeclampsia was defined as diastolic BP of ≥90 mm Hg or systolic BP ≥140 mm Hg measured on 2 occasions at least 6 hours apart, combined with proteinuria (1+ protein on dipstick, ≥300 mg total protein within a 24 hour urine collection, or ratio of protein to creatinine ≥0.3 mg/mmol). Only women with preeclampsia with an admitting BP of <160 mm Hg systolic and <110 mm Hg diastolic were included. Patients with the diagnosis of chronic hypertension with superimposed preeclampsia were excluded. These 3 groups were then compared with a control group, which was defined as all pregnant women with no past or current medical disease, no obstetric issues in the current pregnancy, and no tobacco, alcohol, or recreational drug use.
Maternal predictor variables included maternal characteristics: singleton vs multiple gestation, prepregnancy and delivery body mass index, admitting systolic and diastolic BP, gestational age on admission, substance use, and comorbidities ( Table 1 ). Maternal outcome variables included length of stay, delivery mode, stillbirth, nonreassuring fetal status, abruption, uterine rupture, hysterectomy, postpartum hemorrhage, transfusion, blood loss, ICU admission, thrombosis, postpartum hypertension, seizures, and death.
| Maternal characteristics | Mild chronic hypertension (n = 2531) | Gestational hypertension (n = 4918) | Mild preeclampsia (n = 5274) | Control group (n = 15,221) | P value |
|---|---|---|---|---|---|
| Maternal age, y a | 29.5 ± 6.6 | 26.9 ± 6.1 | 28.2 ± 6.7 | 26.7 ± 6.3 | < .0001 |
| Race, n (%) | |||||
| White | 821 (32.4) | 2827 (57.5) | 2712 (51.4) | 4443 (29.2) | < .0001 |
| Black/non-Hispanic | 1285 (50.8) | 1090 (22.2) | 1131 (21.4) | 6160 (40.5) | |
| Hispanic | 299 (11.8) | 733 (14.9) | 736 (14.0) | 1925 (12.7) | |
| Asian/Pacific Islander | 35 (1.4) | 71 (1.4) | 283 (5.4) | 402 (2.6) | |
| Other | 91 (3.6) | 197 (4.0) | 412 (7.8) | 2291 (15.1) | |
| Parity, n (%) | |||||
| 0 | 906 (35.8) | 2876 (58.5) | 3260 (61.8) | 6568 (43.2) | < .0001 |
| 1 | 673 (26.6) | 1031 (21.0) | 1044 (19.8) | 4729 (31.1) | |
| 2 | 463 (18.3) | 590 (12.0) | 490 (9.3) | 2435 (16.0) | |
| 3 | 243 (9.6) | 251 (5.1) | 243 (4.6) | 894 (5.9) | |
| ≥4 | 246 (9.7) | 170 (3.5) | 237 (4.5) | 595 (3.9) | |
| Fetuses, n (%) | |||||
| 1 | 2462 (97.3) | 4730 (96.2) | 4963 (94.1) | 15,039 (98.8) | < .0001 |
| 2 | 67 (2.7) | 172 (3.5) | 300 (5.7) | 180 (1.2) | |
| ≥3 | 2 (0.1) | 16 (0.3) | 11 (0.2) | 2 (0.01) | |
| Body mass index, kg/m 2 a | |||||
| Prepregnancy | 32.9 ± 9.4 | 28.3 ± 7.2 | 27.2 ± 7.0 | 26.1 ± 6.3 | < .0001 |
| At delivery | 37.9 ± 8.9 | 34.2 ± 7.1 | 33.5 ± 7.2 | 31.4 ± 6.2 | < .0001 |
| Blood pressure at admittance, mm HG a | |||||
| Systolic | 140.9 ± 17.2 | 142.3 ± 15.0 | 137.2 ± 12.5 | 122.4 ± 13.4 | < .0001 |
| Diastolic | 83.8 ± 13.5 | 87.4 ± 12.4 | 83.8 ± 11.9 | 73.2 ± 11.1 | < .0001 |
| Mean arterial | 102.8 ± 13.5 | 105.7 ± 12.1 | 101.6 ± 10.9 | 89.6 ± 10.8 | < .0001 |
| Gestational age at delivery, wk | |||||
| Overall a | 37.2 ± 3.2 | 37.4 ± 2.8 | 37.2 ± 3.2 | 39.2 ± 1.8 | < .001 |
| <30, n (%) | 128 (5.1) | 146 (3.0) | 216 (4.1) | 92 (0.6) | |
| 30-33 6/7 , n (%) | 158 (6.2) | 317 (6.5) | 439 (8.3) | 156 (1.0) | |
| 34-36 6/7 , n (%) | 486 (19.2) | 908 (18.5) | 1010 (19.2) | 713 (4.7) | |
| 37-37 6/7 , n (%) | 413 (16.3) | 817 (16.6) | 685 (13.0) | 1333 (8.8) | |
| 38-38 6/7 , n (%) | 571 (22.6) | 1103 (22.4) | 993 (18.8) | 2954 (19.4) | |
| 39-39 6/7 , n (%) | 502 (19.8) | 988 (20.1) | 994 (18.9) | 4932 (32.4) | |
| >40, n (%) | 273 (10.8) | 639 (13.0) | 937 (17.8) | 5041 (33.1) | |
| Insurance, n (%) | |||||
| Private | 1154 (45.6) | 2840 (57.8) | 3735 (70.8) | 8030 (52.8) | < .0001 |
| Public | 1240 (49.0) | 1810 (36.8) | 1033 (19.6) | 6442 (42.3) | |
| Substance use, n (%) | |||||
| Smoking | 264 (10.4) | 262 (5.3) | 212 (4.0) | 0 | < .0001 |
| Alcohol | 86 (3.4) | 115 (2.3) | 94 (1.8) | 0 | < .0001 |
| Illicit drug use | 116 (4.6) | 59 (1.3) | 69 (1.3) | 0 | < .0001 |
| Maternal comorbidities, n (%) | |||||
| Gestational diabetes mellitus | 178 (7.1) | 248 (5.0) | 299 (6.4) | 0 | < .0001 |
| Pregestational diabetes mellitus | 353 (14.0) | 215 (4.4) | 208 (4.0) | 0 | < .0001 |
| Renal disease | 99 (3.9) | 58 (1.2) | 38 (0.7) | 0 | < .0001 |
| Heart disease | 61 (2.4) | 54 (1.1) | 17 (0.3) | 0 | < .0001 |
| Thromboembolic history | 21 (0.8) | 3 (0.07) | 33 (0.7) | 0 | < .0001 |
| Intrauterine growth restriction in current pregnancy b | 225 (9.0) | 415 (8.5) | 553 (10.8) | 875 (5.8) | < .0001 |
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