The stroke rate for pregnant women and new mothers in the U.S. jumped about 54 percent, possibly because more women are obese and suffer from high blood pressure, diabetes and congenital heart disease, according to an American Heart Association study.

The heart association said that pregnancy-related hospitalizations rose 54 percent, to about 6,300 in 2006-7, from about 4,100 in 1994-95, extrapolating figures from a large federal database.

"That is a very, very alarm-raising statistic that we need to take extremely seriously," Dr. Olajide Williams, a neurologist at Columbia University and Harlem Hospital and an American Stroke Association spokesman, told Forbes. "We need to be more aggressive in screening these women for these risk factors."

Elena V. Kuklina, the study's lead author and an epidemiologist at the Centers for Disease Control and Prevention's Division for Heart Disease and Stroke Prevention, said in a statement she that the increase was "substantial."

"When you're relatively healthy, your stroke risk is not that high," Kuklina said. "Now more and more women entering pregnancy already have some type of risk factor for stroke, such as obesity, chronic hypertension, diabetes or congenital heart disease. Since pregnancy by itself is a risk factor, if you have one of these other stroke risk factors, it doubles the risk."

The study was published on Thursday in the American Heart Association's journal Stroke.

Researchers gathered information from a large national database of between five and eight million discharges from 1,000 hospitals and compared the stroke rates from 1994-95 to 2006-07 in women who were pregnant, delivering a baby and who had recently had a baby.

"What we found was there was approximately a 50% increase in all stroke," Kuklina added.

The Associated Press said that the number of strokes is small, considering that around 4 million babies are born each year in the U.S, although pregnancy raises a woman's risk of a stroke because of all the hormone and blood changes that occur.

The study also found that in expectant mothers, the rate of stroke-related hospitalizations rose by 47 percent; while in pregnant women and in women in the post-partum stage, the stroke rate rose to 83 percent.

The rate, however, continued to remain the same for stroke hospitalizations that occurred immediately after childbirth. Pregnant women who were hospitalized following a stroke typically had high blood pressure, the study noted.

Data gathered said that 17 percent of expectant mothers -- prior to childbirth -- had high blood pressure in 2006-07 compared to 11.3 percent in 1994-95. Blood pressure rates in expectant mothers, who are closer to delivery, was 28.5 percent in 2006-07 compared to 23.4 percent during 1994-95.