The first thing to know is that having a heart attack during pregnancy is very rare. The risk is about one in 10,000. The next thing to know is that the risk is 25 percent higher now than it was back in 2002. That’s according to a 2018 study published in the medical journal Mayo Clinic Proceedings. 
You might be surprised to know that heart disease is the number one cause of death for pregnant women. [2,3] Heart attack is on the rise and so is an even more common type of heart disease called cardiomyopathy, which causes weakening of heart muscles. 
You don’t want to worry needlessly, but you do need to be aware. Studies show that only six percent of women with pregnancy-related heart disease have a prior history of heart disease and two-thirds of pregnant women with heart disease are not diagnosed early enough during pregnancy to prevent complications. 
Why Heart Disease and Heart Attack Increases During Pregnancy
The main reason is that pregnancy puts increased stress on your heart. By the time you are in your third trimester, you blood volume has gone up by 50 percent. That means a lot more work for your heart. That increased stress could uncover a lurking risk for heart disease. 
Researchers suspect the rise in heart attacks and heart disease since 2002 is mainly due to two changes. Women are getting pregnant at older ages and more women are obese or overweight during pregnancy.
The recent study on heart attacks found that pregnant women ages 35 to 39 were five times more likely to have a heart attack than women in their 20s. Women over age 40 were ten times more likely. [1-3]
The rise in heart attacks follows a similar rise in the rate of obesity in pregnant women, which is up about 10 percent since 2000. Obesity adds extra work for your heart and is likely to add other heart disease risk factors like diabetes and high blood pressure.  One-fourth of pregnant women who die from heart problems develop high blood pressure during pregnancy. 
What Can You Do?
Start by being aware of your risk factors. The increased risk occurs pregnancy and the two months after pregnancy. Heart attacks occur most commonly around the time of delivery. Risk factors include: 
- Older age
- High blood pressure
- Being African American
- Substance abuse
- A history of heart disease
- A family history of heart disease
One reason heart disease is missed during pregnancy is that the symptoms are similar to symptoms that normally occur during pregnancy. These include shortness of breath, heart palpitations, heartburn, and swelling of your legs. If these symptoms are getting worse and interfering with your daily activities, let you doctor know. 
The good news is that many pregnancy-related heart attacks can be prevented with early diagnosis and treatment. Talk to your doctor about your heart disease risk factors. Maintain a healthy weight. Work with your doctor to manage high blood pressure or diabetes. 
The risk of a heart attack during pregnancy is still extremely low, but this new study is a red flag. Knowing about the danger is the best way to avoid it.
- ScienceDaily, Heart attack risk on the rise for pregnant women and death rate remains high.
- Cleveland Clinic, Pregnant? Why Your Heart (Not Just baby) Needs Your Attention, Too.
- American Heart Association, Heart Disease Causes Pregnancy Related Deaths.