THURSDAY, Jan. 26 (HealthDay News) -- A new survey finds that Hispanic-American mothers have lower rates of pre-term delivery and fewer low birth weight babies, compared to either their non-Hispanic white or black peers. The study is the first conducted in a primarily non-Mexican Hispanic population. It confirms that findings previously noted in Hispanics of Mexican origin are also true for other Hispanics, said study author Dr. Victor Hugo Gonzalez-Quintero, director of maternal fetal medicine at the University of Miami School of Medicine.
"We know that immigrants may have more traditional risk factors, but we fail to acknowledge that they also have many positive factors," added Jane L. Delgado, president and CEO of the National Alliance for Hispanic Health. "This may explain why Hispanic immigrants have better health measures than the first generation that is born in the United States."
The findings appear in the January issue of the Journal of Reproductive Medicine.
As the study pointed out, Hispanics are the fastest-growing minority population in the United States, currently constituting 12.5 percent of the nation's population. Hispanics also represent the majority of residents in Florida's Miami-Dade county, where the study took place.
Hispanics often have lower socioeconomic status than other groups, but they also have better health outcomes, particularly in pregnancy. This phenomenon is known as the "epidemiologic paradox." Overall rates of illness and death are lower in Hispanics than black Americans and comparable to those of whites.
Most of the previous research on the subject had focused on the U.S. West Coast, where the Hispanic population, like that of the overall United States, is primarily Mexican, explained Gonzalez-Quintero.
"Hispanics are a very heterogeneous population," Gonzalez-Quintero said. "The East is a more transitional population in the sense that many people are newly arrived, the levels of acculturation are different. Our population [South Florida] is mostly from the Caribbean, and Central and South America."
Gonzalez-Quintero wanted to see if the phenomenon was true across Hispanic groups.
To that end, he and his colleagues looked at the records of all women who delivered at Jackson Memorial Hospital in Miami over an 11-year-period, covering the entire decade of the 1980s. During the study period, half of all deliveries for the county took place at this hospital, which also handles most of the county's indigent population.
The sample represented close to 81,000 deliveries. Slightly more than one-third (35 percent) of the women were Hispanic, mainly of Caribbean, Central American and South American origin.
The rate of low birth weight babies was just 9 percent for Hispanic mothers, much lower than that of the other two groups included in the study: black non-Hispanics (18 percent) and white non-Hispanics (11 percent).
Hispanic women were also less likely to deliver prematurely, the study found.
"We confirmed that the epidemiological paradox is present as well in this area of the country, and that it's something we should look at," Gonzalez-Quintero said.
Most likely, a number of factors collide to explain why Hispanics have lower rates of pre-term delivery. Understanding the reasons, however, could be important.
"If we could figure out why Hispanics have this low rate, there might be something we could do with other minorities," Gonzalez-Quintero said.
Smoking during pregnancy is associated with higher rates of pre-term delivery and lower birth weight. The Hispanic mothers in this study had the lowest rates of smoking during pregnancy, the researchers noted. They also had the highest rates of prenatal care. The exact reasons, however, are unclear.
"Hispanics are such a heterogeneous group. Even though they can be neighbors, their genetic makeup is totally different," Gonzalez-Quintero said. "Despite this, they all have better outcomes. This is something we need to look at."
In a related study, researchers reporting in this week's issue of the federal Morbidity and Mortality Weekly Report noted that women living in Puerto Rico have much higher rates of Cesarean-section deliveries compared to Puerto Rican mothers on the U.S. mainland.
Between 1992-2002, women giving birth in Puerto Rico underwent C-sections at a rate 72 percent higher than their peers in the continental U.S., according to researchers at the U.S. Centers for Disease Control and Prevention (CDC).
"Efforts to reduce the Cesarean-delivery rate in Puerto Rico should focus on lowering the rate of primary Cesearean deliveries, especially among women with low-risk pregnancies," the CDC experts said.
For more on Hispanic health issues, visit the National Alliance for Hispanic Health.