High Blood Pressure and Pregnancy

Dr. Jones: Most women who were trying to become pregnant and had a miscarriage are eager to try to get pregnant again. What have we learned about how women might prepare for the next try? This is Dr. Kirtly Jones from Obstetrics and Gynecology at University of Utah Health, and this is "The Seven Domains of Women's Health" on The Scope.

Announcer: Covering all aspects of women's health, this is "The Seven Domains of Women's Health" with Dr. Kirtly Jones on The Scope.

Dr. Jones: Early pregnancy loss, miscarriage, is pretty common. Rates vary from 15% to 30% depending on the age of the woman and how early a pregnancy is detected. Certainly, we know that some things are associated with higher rates of early miscarriage, such as age of the mom, especially after 40, and poorly controlled diabetes, for example. However, for young women who had one or two miscarriages, are there any new clues about causes or things women can do to increase the chance that the next pregnancy would be healthy and go to term?

Now, early miscarriage has been the focus of a lot of research in the past 15 years as well as the focus of a lot of cultural myths for thousands of years. We hear from our mothers, sisters, and aunties that we should eat this, don't eat that, do this, don't do that. One recommendation that had been around for about 15 years is that low-dose aspirin, a baby aspirin of 81 milligrams, would increase the chances of pregnancy and decrease the risk of miscarriage.

Several years ago, a large randomized trial done here at the University of Utah and in three other centers around the country looked at over 1,000 young women under 40 who are healthy and had a history of 1 or 2 early miscarriages. These women are randomized with baby aspirin and folic acid, or just folic acid, and their next pregnancies were studied very carefully. Overall, they found that the majority of women had successful pregnancies, about 58%, with the next try whether they took the aspirin or not, and aspirin didn't decrease the chance of miscarriage.

Now, this work was reported in 2014, but there have been some other interesting findings from this study and one that was reported recently. Women in this study were mostly white, often overweight, and the average was 29. The average blood pressure was 111/72. Now, that's a nice average blood pressure for young women. But here's what's new.

For every 10 points increase in the diastolic blood pressure, that's the lower number, there was an increase of 18% in the risk of miscarriage. This means that young women with slightly elevated blood pressure but not a diagnosis of hypertension were increased risk of miscarriage. The study in the journal "Hypertension" found no association of blood pressure with the ability to get pregnant or the rate to get pregnant. They controlled for smoking, body mass index, marital status, education, and other factors that are known to be independently related to miscarriage. And that means that the blood pressure alone or with other factors that they couldn't measure is associated with an increased risk of miscarriage.

Now, we know that hypertension before pregnancy is associated with a number of various very serious problems in pregnancy including still birth, pre-eclampsia, pre-term birth, and placental abruption where the placenta prematurely separates from the uterus before the birth of the baby. This finding that even what we might call pre-hypertension, just a medium elevation of blood pressure in young women, is associated with miscarriage is important. So what's the takeaway from this?

First of all, all pregnancy should be started with women in their best emotional, physical, social, and financial health. If you're thinking about getting pregnant, stopping smoking and maintaining a healthy weight are important because both of these conditions are associated with miscarriage, smoking, and being overweight. And if you can get your blood pressure checked before you get pregnant and if the lower number is between 70 and 80, you might consider increasing your exercise, being mindful to manage your stress, and consider a diet lower in salt and higher in vegetables and healthy fats, kind of that Mediterranean diet thing that we've talked a lot on The Scope a lot.

No matter what happens in your pregnancy, these changes are good for your current and long-term health. Of course, if you are hypertensive, with the lower number over 80, you should get your blood pressure under control before pregnancy with diet and exercise, or with medication. This is really important not just for you, but for the new person you hope to grow. And thanks for joining us on The Scope.

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