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About HDP

Hypertensive disorders of pregnancy (HDP) includes a spectrum of diseases including chronic hypertension, gestational hypertension, pre-eclampsia, and eclampsia.

HDP affects 7% of pregnancies, or approximately 10,000 pregnant women in Ontario each year
Women with HDP are at an increased risk of hypertension, diabetes, chronic kidney disease, and premature cardiovascular disease (CVD) (1, 2).
The increase in CVD risk factors including dyslipidemia, obesity, and hypertension starts as early as 1-year pregnancy (3), while the increased risk of cardiac events starts in the first decade post-pregnancy (4).

Clinical practice guidelines recommend that women with HDP should be informed of the increased risk of CVD associated with HDP, and adopt healthy lifestyle interventions to mitigate the risk (5). Our aim is to summarize the available evidence for you, noting areas in which evidence is lacking in this population.

Know the Risks

While mortality from cardiovascular disease is declining in the general population, mortality from CVD is increasing in women ages 35-54 (6). Women with a history of HDP are a high-risk subgroup of women in this demographic, and the postpartum period is a “window of opportunity” for CVD risk reduction (7).

It remains unknown whether HDP is an independent risk factor for future CVD or whether the complicated pregnancy is a “stress test”, and unmasks women at high-risk of CVD.

We do know, from multiple studies, that women who have had gestational hypertension, pre-eclampsia, or eclampsia are at an increased risk of developing CVD-risk factors and cardiovascular events. These risks remain high after adjusting for shared risk factors such as age, BMI, DM, smoking and hypertension status (2,8).

Meta-analyses have shown that after pre-eclampsia, women have:

3.6-4x increased risk of heart failure

2-2.5x increased risk of coronary artery disease

2x increased risk of stroke

Women post HDP are also at increased risk of hypertension and diabetes (9,10).

An Ontario cohort study revealed that women with pre-eclampsia/ gestational hypertension have 2x the risk of developing diabetes in the 16 years post pregnancy, compared to women without HDP (9).

To diagnosis one woman with hypertension, the number needed to screen at age 35 is 1 in 9 for women with a HDP vs. 1 in 38 in women with uncomplicated pregnancies (10).

Lower the Risks: Health behavioural counselling

Maintaining a healthy weight may be particularly important in women with a history of HDP. In a study of over 54,000 parous women from the Nurse’s Health Study II, the authors looked at the relationship between various known lifestyle factors and chronic hypertension, in women with and without a history of HDP. The authors found that being overweight or obese was consistently associated with a higher risk of chronic hypertension, with the risk being amplified in women with a history of HDP. In other words, higher BMI was a positive and additive effect modifier on the association between HDP and chronic hypertension (11).

While lifestyle behaviour counselling is time and resource intensive, it has been shown to be effective in preventing postpartum weight retention (12).

The 2018 C-CHANGE guidelines (13) highlight the following evidence-based dietary patterns to improve CVD health:

• Mediterranean dietary pattern

• Portfolio dietary pattern

• DASH dietary pattern

• Others: Dietary patterns high in nuts (≥ 30 g/d) • Dietary patterns high in legumes (≥ 4 servings/wk) • Dietary patterns high in olive oil (≥ 60 mL/d) • Dietary patterns rich in fruits and vegetables (≥ 5 servings/d) • Dietary patterns high in total fibre (≥ 30 g/d); and whole grains (≥ 3 servings/d) • Low glycemic load or low glycemic index dietary patterns • Vegetarian diet

Canada’s Dietary Guidelines, updated in 2019, is another great reference- incorporating some key updates from previous national dietary recommendations. There is an increased focus on promoting a diet high in vegetables, fruits, whole grains, and plant-based protein options. Canada’s Food Guide now also notes the importance of acquiring adequate skills and knowledge in healthy eating- from food preparation at home to reading food labels.

Lower the Risks: Risk factor modification

Clinical practice recommendations vary on how to best follow-up women post-HDP, reflective of a paucity of evidence in this area (14, 15). A Canadian Best Practice Statement will be released in the near future from the Canadian Post-pregnancy Clinical Network (16). It is worth noting that the American Heart Association considers a history of preeclampsia, gestational diabetes, or pregnancy-induced hypertension as a “major cardiovascular risk factor”, in the same category as smoking, hypertension, or a family history of CVD (6).

Screening for elevated BMI, smoking and other lifestyle behavioural counselling:

Health behaviour modification is recommended in clinical practice guidelines and is the cornerstone of preventative therapy in this population (15).

Screening for hypertension

An annual physical examination with blood pressure measurements is recommended in women with a history of HDP (5,15,17). High rates of masked-hypertension have been reported at 1-year post pre-eclampsia, suggesting that out-of-office blood pressure measurements may be important (18).

No specifically defined blood pressure treatment thresholds or targets have been studied in this population (15) but treatment goals as per Hypertension Canada are recommended, with target BP <140/90 mm Hg in most women.

Screening for kidney disease

Quantification of proteinuria is recommended following HDP (15). Screening at 6 months postpartum followed by annual measurement of albumin-to-creatinine ratio, protein-to-creatinine ratio or 24-hour protein measurement is recommended. Albuminuria may persist after an episode of a hypertensive disorder of pregnancy, and this may help with risk-stratification, along with blood pressure measurements (17). Women with increasing amounts of proteinuria, >300 mg/day of proteinuria, microscopic hematuria, or abnormal renal function should be evaluated by a nephrologist to evaluate for underlying intrinsic kidney disease.

Screening for dyslipidemia

The “2016 Canadian Cardiovascular Society Guidelines for the Management of Dyslipidemia for the Prevention of Cardiovascular Disease in the Adult” recommends screening for dyslipidemia in women with a history of HDP, irrespective of age (19). Screening can begin 6-12 months postpartum and then annually.

It is recommended that the risks/benefits of statin therapy are discussed on an individual basis. Counselling is required to avoid statin use during future pregnancies (19).

Screening for dysglycemia

While HDP increases the risk of future diabetes (9). It is reasonable to screen with a 75-gram oral glucose tolerance test (OGTT) or a HbA1C between 6 weeks to 6 months postpartum and annually thereafter.

Help your patient plan ahead

Women with a history of a hypertensive disorder of pregnancy may have questions about what to expect in a future pregnancy.

Risk of recurrence

The risk of developing a recurrent hypertensive disorder of pregnancy has been described at around 20%, but this varies depending on the patient’s co-morbidities, and details of the HDP in the index pregnancy (HDP earlier in pregnancy is associated with a higher risk of recurrence) (20). The risk of recurrence should therefore be individualized.

Weight loss between pregnancies has been associated with a reduced risk of recurrence of HDP in the subsequent pregnancy, further amplifying the need for intensive behavioural modification in overweight or obese patients with a history of HDP (21).

Prevention in future pregnancies

Patients at high risk of recurrent HDP (including all patients with a history of HDP) should be followed in a high-risk OB centre if possible, if not consultation with OB/OB medicine should be sought. Early referral is key, given that preventative interventions must be started early (low dose aspirin therapy, for example, before 16 weeks gestation). Patients with a diet low in calcium should be prescribed calcium supplementation for HDP-prevention. Usual practice peri-conceptional folic acid is recommended (22).

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References

(1) Butalia S, Audibert F, Cote AM, et al. Hypertension Canada's 2018 Guidelines for the Management of Hypertension in Pregnancy. Can J Cardiol. 2018;34:526-531.

(2) Ray JG, Vermeulen MJ, Schull MJ, Redelmeier DA. Cardiovascular health after maternal placental syndromes (CHAMPS): population-based retrospective cohort study. Lancet. 2005;366:1797-1803.

(3) Smith GN, Walker MC, Liu A, et al. A history of preeclampsia identifies women who have underlying cardiovascular risk factors. Am J Obstet Gynecol. 2009;200:58 e51-58.

(4) Chan SE, Pudwell J, Smith GN. Effects of Preeclampsia on Maternal and Pediatric Health at 11 Years Postpartum. Am J Perinatol. 2018.

(5) Bro Schmidt G, Christensen M, Breth Knudsen U. Preeclampsia and later cardiovascular disease - What do national guidelines recommend? Pregnancy Hypertens. 2017;10:14-17.

(6) Mosca L, Benjamin EJ, Berra K, et al. Effectiveness-based guidelines for the prevention of cardiovascular disease in women--2011 update: a guideline from the american heart association. Circulation. 2011;123:1243-1262.

(7) Brown HL, Warner JJ, Gianos E, et al. Promoting Risk Identification and Reduction of Cardiovascular Disease in Women Through Collaboration With Obstetricians and Gynecologists: A Presidential Advisory From the American Heart Association and the American College of Obstetricians and Gynecologists. Circulation. 2018;137:e843-e852.

(8) Wu P, Haththotuwa R, Kwok CS, et al. Preeclampsia and Future Cardiovascular Health: A Systematic Review and Meta-Analysis. Circ Cardiovasc Qual Outcomes. 2017;10.

(9) Feig DS, Shah BR, Lipscombe LL, et al. Preeclampsia as a risk factor for diabetes: a population-based cohort study. PLoS Med. 2013;10:e1001425.

(10) Groenhof TKJ, Zoet GA, Franx A, et al. Trajectory of Cardiovascular Risk Factors After Hypertensive Disorders of Pregnancy. Hypertension. 2019;73:171-178.

(11) Timpka S, Stuart JJ, Tanz LJ, Rimm EB, Franks PW and Rich-Edwards JW. Lifestyle in progression from hypertensive disorders of pregnancy to chronic hypertension in Nurses' Health Study II: observational cohort study. BMJ. 2017; 358: j3024.

(12) Nicodemus NA, Jr. Prevention of Excessive Gestational Weight Gain and Postpartum Weight Retention. Curr Obes Rep. 2018; 7: 105-11.

(13) Tobe SW, Stone JA, Anderson T, et al. Canadian Cardiovascular Harmonized National Guidelines Endeavour (C-CHANGE) guideline for the prevention and management of cardiovascular disease in primary care: 2018 update. CMAJ. 2018; 190: E1192-E206.

(14) Schmidt GB, Christensen M, Knudsen UB. Preeclampsia and later cardiovascular disease – What do national guidelines recommend?, Pregnancy Hypertension, 2017

(15) Gamble DT, Brikinns B, Myint PK and Bhattacharya S. Hypertensive Disorders of Pregnancy and Subsequent Cardiovascular Disease: Current National and International Guidelines and the Need for Future Research. Front Cardiovasc Med. 2019; 6: 55.

(16) Dayan N and Nerenberg K. Postpartum Cardiovascular Prevention: The Need for a National Health Systems-Based Strategy. Can J Cardiol. 2019; 35: 701-4.

(17) Piccoli GB, Cabiddu G, Castellino S, et al. A best practice position statement on the role of the nephrologist in the prevention and follow-up of preeclampsia: the Italian study group on kidney and pregnancy. J Nephrol. 2017; 30: 307-17.

(18) Benschop L, Duvekot JJ, Versmissen J, van Broekhoven V, Steegers EAP and Roeters van Lennep JE. Blood Pressure Profile 1 Year After Severe Preeclampsia. Hypertension. 2018; 71: 491-8

(19) Anderson TJ, Gregoire J, Pearson GJ, et al. 2016 Canadian Cardiovascular Society Guidelines for the Management of Dyslipidemia for the Prevention of Cardiovascular Disease in the Adult. Can J Cardiol. 2016; 32: 1263-82.

(20) van Oostwaard MF, Langenveld J, Schuit E, et al. Recurrence of hypertensive disorders of pregnancy: an individual patient data metaanalysis. Am J Obstet Gynecol. 2015; 212: 624 e1-17.

(21) Mostello D, Jen Chang J, Allen J, Luehr L, Shyken J and Leet T. Recurrent preeclampsia: the effect of weight change between pregnancies. Obstet Gynecol. 2010; 116: 667-72

(22) Society of Obstetricians and Gynaecologists of Canada. SOGC clinical practice guideline No. 307. Diagnosis, evaluation, and management of the hypertensive disorders of pregnancy: Executive summary. https://www.jogc.com/article/S1701-2163(15)30588-0/pdf (Accessed on January 27, 2020).