High Blood Pressure and Pregnancy

Podcast Transcript

Announcer:

Welcome to Love Your Heart, brought to you by Cleveland Clinic's Sydell and Arnold Miller Family Heart, Vascular & Thoracic Institute. These podcasts will help you learn more about your heart, thoracic and vascular systems, ways to stay healthy and information about diseases and treatment options. Enjoy!

Deirdre Mattina, MD:

I'm very delighted to be here with all of you today. I'm going to move right ahead and dive into hypertension and pregnancy. First, I think it's really important for us to recognize how prevalent maternal mortality is in the US and the healthcare disparities that it has created in treating women. Over the last few years, we can see that Black women are three to four times more likely to die in childbirth than other ethnic groups, and that's why I think it's so important that we talk about this topic today.

First, getting to the definition of hypertensive disorders in pregnancy. Just like in any time, we're defining hypertension as a blood pressure greater than 140/90 on at least two occasions, we have a severe range of high blood pressure that can be a systolic greater than 160 or a diastolic greater than 110 that's sustained for at least 15 minutes, and these hypertensive disorders of pregnancy effect about 5-10% of pregnancies, and previously, it can affect long-term cardiovascular disease risk.

When we further break down what these hypertensive disorders are, we're really talking about chronic hypertension, which may be pre-existing hypertension prior to pregnancy or occurring less than 20 weeks of gestation, and importantly, it lasts longer than 3 months postpartum. Gestational hypertension, in contrast, happens later in pregnancy, after 20 weeks of gestation, and it's really isolated to the pregnancy and resolves by 3 months postpartum. And then we move into our more severe forms of hypertensive disorders, which are preeclampsia, chronic hypertension with superimposed preeclampsia, eclampsia, and the HELLP syndrome.

So it's important, if we have a woman that is contemplating pregnancy and has pre-existing hypertension, to really talk and think about this as preconception counseling, because we know that women with chronic hypertension getting pregnant, about 1 in 4 of them are going to develop preeclampsia in their pregnancy. So searching for any kidney disease, which can also increase risk of preeclampsia. Also, many of these women are young, so we want to make sure that we have done a thorough workup into the cause and the etiology of their hypertension to exclude any other secondary causes like thyroid dysfunction, renal artery stenosis, et cetera. And then we're really going to work hard at looking at modifiable risk factors. So obviously lifestyle things like salt intake, exercise, other things that we can work on to get the blood pressure and other risk factors in check before they get pregnant.

When we're talking about chronic hypertension in pregnancy, especially, as I alluded to, this has a very high risk of preeclampsia, which can portend future cardiovascular disease. These numbers are on the rise in recent decades, about 67% increase of women with chronic hypertension and pregnancy. And again, we can see this healthcare disparity because about the largest increase that we've seen in chronic hypertension in pregnancy comes within African American women. We believe that these numbers are increasing because of the obesity epidemic and advancing maternal age in pregnancy. So this has kind of changed the game on how we think about hypertension, and when we're defining hypertension in pregnancy, we know that we're targeting that top number of less than 140/90.

When we're looking at preeclampsia, again, the standard high blood pressure essentially after 20 weeks of gestation is pretty rare to see preeclampsia early on in pregnancy. Classically, this is accompanied by proteinuria, but you can still diagnose preeclampsia with other severe features like thrombocytopenia, renal insufficiency, impaired liver function, pulmonary edema, or other CNS findings like headache or vision changes as well. This is going back to older data from studies in the '80 and early 2000s that we can see a link between preeclampsia and chronic hypertension. And I think this is really important because we have seen preeclampsia in the past kind of parlayed into this isolated incidence of pregnancy and not really thought of how it can affect long-term outcomes, but we're really seeing that even in preeclampsia, this may have resolved very quickly after pregnancy, but there is almost a fourfold increase in developing chronic hypertension.

This is important because worldwide chronic hypertension is one of the main causes of cardiovascular mortality and heart failure, and if we think about women developing high blood pressure in the 10 to 15 years postpartum, that really would be premature onset preeclampsia also associated with a two-fold increase in ischemic heart disease and also all-cause mortality has a slight increase with preeclampsia. So these are not benign findings and I think it's important that we educate women in the postpartum phase about what these future risks are in my postpartum heart program when I'm educating women that have had hypertensive disorders in pregnancy, including preeclampsia.

We can look in the non-pregnant state when we have a uterus. When we're non-pregnant, there's not much that we have to do in terms of blood flow. These spiral arteries invade, they sort of dilate, provide nitric oxide and blood flow that's needed. Obviously in the pregnant state, these spiral arteries invade and cause this sheer stress, which up regulates these upstream arteries, releases a lot more nitric oxide, it can triple, quadruple the uterine blood flow. The baby is happy, placenta is happy, and we have a nice normal delivery. However, in preeclampsia there is this microvascular dysfunction. The spiral arteries do not dilate enough, they're not creating enough upstream stress to release this nitric oxide, blood flow is decreased, the placenta itself can be smaller and hypoxic and even have infarcts, baby then releases stress hormones, and then this begets the preeclampsia.

What we're really trying to do is increase uterine blood flow and we're trying to reduce vasoconstriction and increase vasodilation. Generally in pregnancy, we upregulate estrogen levels. In the preeclampsic state, we have shown that there are lower levels of estrogen. That can be for several reasons. We can see these lower synthesis of esterase in people that have gestational diabetes and also in obesity there is some association with higher leptin levels and reduced estrogen. And so these pathways are not upregulated as they naturally would in the pregnant state, and then that, in turn, creates that combination of vasoconstriction instead of vasodilation. This is what we consider as a failed stress test for women when they have these adverse pregnancy outcomes of hypertension and preeclampsia. This is really sort of a signal or the first sign that may be linked to future heart disease.

We have seen promises in the role of aspirin. We really look for, what are the risk factors for preeclampsia so we can identify those at moderate and high risk that may benefit for some intervention. The highest risk features are going to be any chronic medical conditions like diabetes, hypertension, lupus, renal disease, and moderate risk factors are going to be things like obesity, family history, advanced maternal age, or other risk factors that could be associated like personal history of low birth weight in the past. And so the reason why aspirin is thought to be important is because it can increase vascular relaxation through the nitric oxide pathway, but we're really looking to increase blood flow through the uterine artery.

The NICE guidelines and the USPSTF guidelines are pretty congruent in their recommendations. If there is one or more moderate risk factor, it advocates for aspirin for preeclampsia prophylaxis beginning at 12 weeks, and if there is one high risk factor, then that also advocates for the use of aspirin for preeclampsia prophylaxis after 12 weeks. I think, most commonly, we're using 81 milligrams in the US, but you may see sometimes where I will recommend the use of 162 milligrams because the data is strongest with 100 milligrams.

Also down the pike are statins. These are good for preeclampsia because, as we looked at studies of human carotid plaques, we can see that statins can decrease plaque inflammation, they reduce platelet reactivity and inflammatory cells. So this is how it may be used in preeclampsia prophylaxis.

Again, I leave you with these key management goals that really encompass blood pressure, lifestyle, and future cardiovascular risk, and I thank you so much for your time.

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