It is within the realm of possibility that your pregnancy may place you at risk for future heart problems. Two separate studies indicate there is some connection between pregnancy and heart health, although neither proves a direct cause-and-effect.

In one, data indicates that a woman's risk of an abnormal heart rhythm – also know as “atrial fibrillation” – increases with each pregnancy she has. The other study shows that women who experience a pre-term delivery have a 40 percent higher increased risk of heart attack or stroke later in life.

"There's something about pregnancy itself that predisposes women toward this risk," said Dr. Jorge Wong, lead author of the first study. He's a cardiologist with the Population Health Research Institute at McMaster University in Hamilton, Ontario.

Wong's team examined data from 34,639 participants in the Women's Health Study, an ongoing project conducted by Harvard Medical School and Brigham and Women's Hospital in Boston. After an average of 20 years of follow-up, the scientists discovered that 1,532 of the test subjects had developed atrial fibrillation, an irregular heart beat that increases the risk of stroke or heart failure. Controlling for other factors, women with a single pregnancy had a 15 percent increased risk of atrial fibrillation compared to women who were never pregnant. The risk increased with the number of pregnancies” a 20 percent increased risk after two or three pregnancies, 36 percent after four to five pregnancies, and a 46 percent increased risk of atrial fibrillation after six or more pregnancies.

The second study hinting at some connection between pregnancy and heart health involved more than 70,000 participants in a separate Harvard-led women's health research project, the Nurses' Health Study. The researchers discovered that women who deliver a baby before 37 weeks gestation in their first birth have a 40 percent greater risk of later heart disease, compared to women whose deliveries occurred on time, that is, at or after 37 weeks. They also learned that women who deliver before 32 weeks gestation are at twice the risk compared to full-term deliveries.

"The pre-term delivery is an early warning sign that these women may be at increased risk," said lead author Lauren Tanz.

What's the science that accounts for the link between pregnancy and heart health? Doctors still aren't quite sure.

"There are... documented cardiac changes that happen due to pregnancy which are always thought to completely resolve at the end of the pregnancy," Wong added. "But it's also been speculated that in women who have multiple pregnancies, these structural changes may take longer to resolve."

Tanz counsels caution, saying that it couldn't hurt for women who have delivered pre-term or have experienced multiple pregnancies to pay extra attention to their heart health. She urges them to eat right, exercise, never smoke and limit their alcohol consumption.

Sources: US National Library of Medicine