Risk of Hypertension Following Hypertensive Disorders of Pregnancy

Caitlin Register, Mercer University College of Pharmacy

Per the United States Preventive Services Task Force (USPSTF), preeclampsia affects approximately four percent of pregnancies in the United States, and is the second leading cause of maternal mortality worldwide. This condition may lead to stroke, eclampsia, and organ failure. The USPSTF recommends that blood pressure measurements be obtained during each prenatal care visit throughout pregnancy for screening purposes. [1] The American College of Obstetricians and Gynecologists suggests administration of daily low dose aspirin beginning in the late first trimester of pregnancy as a preventative measure for women at risk for preeclampsia. These include women with a history of early-onset preeclampsia with preterm delivery less than 34 weeks gestation and women with a history of preeclampsia in more than one prior pregnancy. For women diagnosed with gestational hypertension, preeclampsia, or superimposed preeclampsia, blood pressure monitoring is recommended at least 72 hours postpartum and again seven to ten days after delivery. [2] According to the American Heart Association, history of preeclampsia or pregnancy-induced hypertension may put women at risk for cardiovascular disease. [3]

Risk of post-pregnancy hypertension in women with a history of hypertensive disorders of pregnancy: nationwide cohort study
Design Cohort; N= 1,025,118
Objective To determine how soon after delivery the risk of post-pregnancy hypertension increases in women with hypertensive disorders of pregnancy and how the risk evolves over time
Study Groups Normotensive (n= 984,865); gestational hypertension (n= 8,693); moderate preeclampsia (n= 24,057); severe preeclampsia (n= 7,503)
Methods Included were women who had at least one pregnancy that lasted 20 or more weeks and ended in live birth or stillbirth between 1978 and 2012, and who were living in Denmark at some point during the follow-up period, 1995-2012. Excluded were women with any cardiac or circulatory system disorder registered in the national patient register before their  first delivery or before 1995, whichever came later, and women with known or potential pregestational hypertension.

Gestational hypertension was defined as hypertension without proteinuria, and moderate preeclampsia as mild or moderate hypertension with proteinuria. Severe preeclampsia fulfilled criteria for moderate preeclampsia, with the addition of severe hypertension, severe proteinuria, signs of organ failure, or generalized seizures.

Duration 1978-2012
Primary Outcome Measure New onset post-pregnancy hypertension, and hazard ratios estimated using Cox regression
Baseline Characteristics
Normotensive Gestational hypertension Moderate pre-eclampsia Severe pre-eclampsia
Age, years, n (%)
  <20 14,138 (1.4) 56 (0.6) 314 (1.3) 134 (1.8)
  20-24 108,333 (11.0) 810 (9.3) 3,006 (12.5) 1,051 (14.0)
  25-29 279,569 (28.4) 2,554 (29.4) 7,590 (31.6) 2,567 (34.2)
  30-34 258,279 (26.2) 2,277 (26.2) 6,089 (25.3) 2,131 (28.4)
  35-39 166,099 (16.9) 1,485 (17.1) 3,555 (14.8) 1,016 (13.5)
  40-44 102,678 (10.4) 888 (10.2) 2,155 (9.0) 427 (5.7)
  45-49 44,445 (4.5) 467 (5.4) 1,003 (4.2) 141 (1.9)
  ≥50 11,324 (1.2) 156 (1.8) 345 (1.4) 36 (0.5)
Parity, n (%)
  1 698,753 (70.9) 7,087 (81.5) 19,955 (82.9) 6,700 (89.3)
  2 220,210 (22.4) 1,248 (14.4) 3,281 (13.6) 634 (8.4)
  ≥3 65,902 (6.7) 358 (4.1) 821 (3.4) 169 (2.3)
Diabetes, n (%) 4,667 (0.5) 111 (1.3) 385 (1.6) 129 (1.7)
Results
Hypertension occurrence following most recent pregnancy
Normotensive Severe preeclampsia Moderate preeclampsia Gestational hypertension
Time, years Events, n Events, n Hazard ratio (95% CI) Events, n Hazard ratio (95% CI) Events, n Hazard ratio (95% CI)
<1 2,326 327 24.5 (21.8- 27.6) 442 11.6 (10.4- 12.8) 426 23.7 (21.4- 26.4)
1 3,278 115 6.45 (5.35- 7.78) 280 5.25 (4.64- 5.94) 220 9.65 (8.41- 11.1)
2 3,880 92 4.61 (3.75- 5.68) 262 4.35 (3.83- 4.93) 178 7.16 (6.15- 8.32)
3 4,219 89 4.22 (3.42- 5.21) 230 3.61 (3.16- 4.12) 163 6.25 (5.34- 7.31)
4 4,406 82 3.81 (3.06- 4.75) 249 3.75 (3.30- 4.27) 158 6.17 (5.26- 7.24)
5 4,782 72 3.20 (2.53- 4.04) 269 3.75 (3.32- 4.25) 130 4.93 (4.14- 5.87)
6 4,886 66 2.93 (2.29- 3.69) 253 3.44 (3.03- 3.91) 136 5.18 (4.37- 6.15)
7 5,172 74 3.17 (2.52- 3.99) 263 3.32 (2.93- 3.76) 136 5.00 (4.21- 5.94)
8 5,294 70 2.98 (2.35- 3.78) 258 3.20 (2.82- 3.63) 112 4.12 (3.41- 4.97)
9 5,457 69 2.90 (2.29- 3.69) 274 3.32 (2.94- 3.76) 109 4.12 (3.40- 4.98)
10-14 32,409 349 2.73 (2.46- 3.04) 1,329 2.67 (2.52- 2.82) 562 3.48 (3.20- 3.78)
15-19 37,683 256 2.24 (1.98- 2.53) 1,346 2.26 (2.14- 2.39) 545 2.71 (2.49- 2.95)
>20 57,119 214 1.71 (1.49- 1.95) 1,679 1.95 (1.86- 2.05) 634 2.26 (2.09- 2.44)
Adverse Events Common Adverse Events: N/A
Serious Adverse Events: N/A
Percentage that Discontinued due to Adverse Events: N/A
Study Author Conclusions The risk of hypertension associated with hypertensive disorders of pregnancy was shown to be high immediately following an affected pregnancy and can persist for more than 20 years. Routine blood pressure monitoring should be initiated soon after pregnancy for these patients.

 

Comparison of three tiers of hypertensive disorders during pregnancy with normotensive pregnant women revealed an increased risk of hypertension following pregnancy. Gestational hypertension, moderate preeclampsia, and severe preeclampsia are already believed to increase risk of cardiovascular disease. This study breaks down the occurrence of hypertension by year following pregnancy in a reportedly large population, showing elevated risk from one year to greater than twenty years postpartum. Routine screening for hypertension with blood pressure monitoring throughout pregnancy, as well as continued screening thereafter for those at increased risk, can allow identification of hypertension early on. Once identified, hypertension can be controlled with medications and healthy lifestyle changes, thereby reducing the risk of negative outcomes.

 

References

[1] Bibbins-domingo K, Grossman DC, Curry SJ, et al. Screening for Preeclampsia: US Preventive Services Task Force Recommendation Statement. JAMA. 2017;317(16):1661-1667.

[2] Hypertension in pregnancy. Report of the American College of Obstetricians and Gynecologists’ Task Force on Hypertension in Pregnancy. Obstet Gynecol. 2013;122(5):1122-31.

[3]Mosca L, Benjamin EJ, Berra K. American Heart Association. E ectiveness-based guidelines for the prevention of cardiovascular disease in women–2011 update: a guideline from the American Heart Association. J Am Coll Cardiol 2011;57:1404-23. doi:10.1016/j.jacc.2011.02.005

[4] Behrens I, Basit S, Melbye M, et al. Risk of post-pregnancy hypertension in women with a history of hypertensive disorders of pregnancy: nationwide cohort study. BMJ. 2017;358:j3078.

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