Despite the low rates of heart attack in women of reproductive age, the risk is increased by three or four times compared with women who are not pregnant, according to a new study.
Overall, the researchers estimate that 6 in 100,000 pregnant women will have a heart attack.
The findings, published in the journal Circulation, also suggest that risks increase with age, with pregnant women over 40 years old 30-times more likely to have a heart attack than pregnant women under the age of 20.
"Even if numbers are low, this represents a dramatic increase," lead author Dr Andra James, from Duke University Medical Center in Durham, North Carolina, told Reuters Health. "However, obstetrician-gynecologists haven't thought much about the problem."