Photo Credit: Jovanmandic
A recent retrospective cohort study analyzed 263,518 pregnant patients without preexisting heart, kidney, or liver disease to assess the risk of severe maternal morbidity (SMM) based on chronic hypertension and hypertensive disorders during pregnancy. The study, which was published online in JAMA Network Open, found that preeclampsia developed in 31.5% of patients with chronic hypertension and 4.7% of those without it. SMM risk was nearly five times higher for chronic hypertension with superimposed preeclampsia and preeclampsia alone, nearly twice as high for gestational hypertension, and only slightly elevated for chronic hypertension without preeclampsia compared to the lowest-risk group.
Physician’s Weekly (PW) spoke with lead author Erica P. Gunderson, PhD, MPH, Division of Research, Kaiser Permanente, to better understand why preeclampsia significantly increases SMM risk, regardless of chronic hypertension status, and highlights the need for targeted prenatal monitoring and prevention strategies.
PW: Given that preeclampsia, whether with or without chronic hypertension, was associated with high SMM rates, how should physicians adjust their prenatal monitoring strategies for patients who are at risk?
Dr. Gunderson: This study set out to advance the research on severe maternal morbidity by designing this study to determine better how pregnancy affects this outcome and how the timing and the type of hypertension when it occurs affects the risk of women.
We set out to separate preexisting chronic diseases, such as cardiovascular disease and kidney disease before pregnancy, from other conditions and complications during pregnancy that contribute to this risk. Previous studies did not differentiate the different risk levels in women.
These adverse outcomes can occur in women with chronic hypertension and without chronic hypertension, but we wanted to determine the risk for most women who are unencumbered by these preexisting chronic diseases. Secondly, in terms of when hypertension occurs in women, we wanted to understand the joint effects of prepregnancy, chronic hypertension, and hypertensive disorders that develop during pregnancy and in terms of how that contributes to severe maternal morbidity.
This study takes a different approach from previous studies and levels the risk factor contributions in looking at the impact of chronic hypertension and whether women develop a hypertensive disorder during pregnancy. The audience probably knows that hypertensive disorders of pregnancy are the strongest risk factors for maternal morbidity and mortality, and they disproportionately affect black women.
We know that preeclampsia is the strongest risk factor for having severe maternal morbidity, which can be stroke, heart failure, myocardial infarction, heart attack, and renal failure, which are serious life-threatening conditions.
What can we do to evaluate risk better in terms of targeted prevention?
We know that these preexisting conditions occur at low rates, but that group with those conditions is always at higher risk of adverse perinatal outcomes and severe morbidity. But what is the risk for women who have chronic hypertension? That affects about 5% of all pregnant women, and for those with chronic hypertension entering pregnancy, about one in three develop preeclampsia, whereas for women who don’t have chronic hypertension, about one in 20 of those patients develop preeclampsia. The study showed that there were patients who developed preeclampsia with or without chronic hypertension had the same fivefold higher increased risk. That’s an interesting question because we have two different types of patients with different risk conditions. One has a much higher occurrence of this very severe outcome.
How can physicians monitor and develop prevention strategies for these different risk factors?
It’s important to develop interventions, and the characteristics before pregnancy can help physicians determine risk strata, which patients they should evaluate more closely, and which risk factors. We know that preeclampsia is very difficult to prevent. Interventions are being developed, but we have limited information on that. Some have suggested lifestyle, and that goes for all patients, but especially patients with chronic hypertension should ask many questions about the management strategy and how to adjust. Prenatal monitoring is an important aspect for future research, but current management. What we found in this study, which I think is crucial to understand and which had not been reported before, is that women with chronic hypertension who did not develop preeclampsia had a risk of severe maternal morbidity that was nearly the same as women without chronic hypertension and no hypertension that developed during pregnancy.
This was a very important finding in the study that avoidance and prevention of preeclampsia could have lower risk for patients with chronic hypertension to almost similar, comparable levels to those who didn’t start pregnancy with chronic hypertension. That focuses the lens on strategies to prevent these hypertensive disorders of pregnancy and all women, but especially those with chronic hypertension.
The study found that patients with uncomplicated chronic hypertension had SMM rates similar to those without. How does that influence decisions regarding earlier intervention and treatment?
I think that if you want to, for all pregnant women, pre-pregnancy risk factor assessment and pre-pregnancy preparation for conception are crucial. There are also recommendations for all women to assess cardiovascular health, for example, before they become pregnant. Trying to get in the best physiologic risk avoidance level possible would be a laudable goal for all pregnant women, and particularly anyone with a preexisting condition such as diabetes or chronic hypertension or even higher than desirable body weight would do well to implement some lifestyle changes such as physical activity, sleep, healthy diet and stress reduction, and any avoidance of other challenges in their lives. Try to ameliorate any risk factors by consulting their primary care provider physician before becoming pregnant to try to be in optimal health to avoid the complications of pregnancy as well as the severe morbidity of delivery outcomes.
With chronic hypertension becoming more prevalent among patients who are pregnant, how can physicians balance the need for targeted screening and intervention without over medicalizing pregnancy in that low-risk population?
The recommendations have been out there from the CDC and other professional organizations for women with chronic conditions or chronic diseases before pregnancy to participate in pre-pregnancy healthcare and intensive healthcare to control those diseases optimally control blood pressure, fine-tune medication, pharmacologic treatment if that’s appropriate for their conditions. They should work with their primary care provider and a team to prepare and achieve the best control of their condition before conception. Now, that takes planning. Planning is sometimes difficult, but if we can implement programs in the healthcare systems that specifically address some of these needs, especially for patients with chronic conditions predating pregnancy, we could go further on what those interventions should be exactly individualized, and I think per patient risk assessment. We’re working very hard on developing models and prediction models that look at various clinical risk factors like blood pressure; even in women who are not recognized or diagnosed with hypertension who are within the normal blood pressure range, those risks associated with adverse outcomes or with development of hypertensive disorders can be evaluated more closely.
We’re working on very applications to the real world to evaluate risk and try to determine those patients in the low-risk category that may also need additional monitoring. There’s a balance of trying to use data and our data systems to get quantitative and better targeted risk evaluation with screening. Then, screening can take potentially basic information about weight, blood pressure, and other biochemical measures that all pregnant women receive. But I think how we use that information and how often we need it are things yet to determine how that would best serve the patients and what interventions would be efficacious to prevent morbidity and complications of pregnancy.
