State-Specific Trends in US Live Births to Women Born Outside the 50 States and the District of Columbia—United States, 1990 and 2000 FREE

MMWR. 2002;51:1091-1095

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Persons born outside the 50 states and the District of Columbia (DC)* comprised an estimated 11.1% (31.1 million) of the U.S. population in 2000,¹ and approximately one fifth of all U.S. births in 2000 were to women in this population. Racial/ethnic disparities in U.S. health outcomes are of public health concern,² and the increasing cultural and linguistic diversity of the U.S. population poses challenges to the delivery of maternal and child health services. This report presents state-specific comparisons of live births in 1990 and 2000 to women born outside the 50 states and DC and compares maternal characteristics and live-birth outcomes for these women with those of state-born mothers (i.e., women born inside the 50 states and DC). The findings indicate that women born outside the 50 states and DC had better birth outcomes than their state-born racial/ethnic counterparts. However, a larger percentage of these women began prenatal care later and had other problems accessing health care, which might reflect economic, cultural, and language barriers. The U.S. public health system and maternal health-care providers should understand and address the health needs of an increasingly diverse population.

Data for 1990 and 2000 were obtained from CDC's National Center for Health Statistics natality files, which are based on birth certificates for all births occurring in the 50 states and DC. These certificates record the mother's place of birth. Previous analyses indicated that maternal characteristics and birth outcomes differed for women born in the 50 states and DC compared with those born elsewhere.^3- 4 Because maternal characteristics and birth outcomes for state-born Puerto Ricans differed from those born elsewhere, results for these two groups are reported separately. Records with missing information on the mother's place of birth (0.2% of all U.S. live births in 1990 and 0.3% in 2000) were excluded from the analysis. Data were analyzed by race/ethnicity. Reported birth outcomes analyzed were preterm (i.e., <37 weeks' gestation) and low birthweight (i.e., <2,500 g). Late prenatal care was defined as care received in the third trimester of pregnancy. Gestational age was computed from the date of the mother's last menstrual period; when the date was missing or inconsistent with birthweight, the clinical estimate of gestation was used.⁵ Unless otherwise noted, all differences reported in this report are statistically significant at p<0.0001.

In 1990, a total of 15.6% of all live births in the United States were to women born outside the 50 states and DC; in 2000, such births represented 21.4% of all U.S. births. In both 1990 and 2000, births to Hispanics comprised the majority of U.S. births to women born outside the 50 states and DC (57.2% in 1990 and 58.6% in 2000); Mexicans accounted for 65.5% of Hispanic births in 1990 and 72.2% in 2000. From 1990 to 2000, among women born outside the 50 states and DC, the percentages of live births to Mexicans increased from 5.7% to 9.0% of all U.S. live births, and births to Central and South Americans increased from 1.9% to 2.5%. Births to Puerto Ricans declined from 0.6% to 0.5% of all U.S. births, and births to Cubans and other Hispanics born outside the 50 states and DC remained the same. Births to non-Hispanics increased from 6.7% to 8.8% overall; births to whites increased from 2.7% to 3.2%, births to blacks increased from 1.1% to 1.6%, and births to Asians/Pacific Islanders (APIs) increased from 2.8% to 4.1%.

In 1990, six states (California, Florida, Illinois, New Jersey, New York, and Texas) accounted for 75.7% of live births to women who were born outside the 50 states and DC. These states accounted for 65.8% of Hispanic births in 2000. During 1990-2000, the percentage of births to women born outside the 50 states and DC increased ≥10% in six states (Arizona, Colorado, Georgia, Nevada, North Carolina, and Oregon); births to Hispanics accounted for the majority of these increases.

In 2000, births to women born outside the 50 states and DC represented a substantial proportion of all births in some population groups. At the state level, approximately 66% of births to APIs in 49 states, >50% of births to Hispanics in 42 states, and >33% of births to non-Hispanic blacks in six states were to women born outside the 50 states and DC. Among non-Hispanics born outside the 50 states and DC, the largest absolute increases in births occurred among whites in New Hampshire (3.4%) and Vermont (2.4%), blacks in DC (2.5%) and Florida (2.5%), and APIs in New York City (4.9%), New Jersey (4.5%), and Hawaii (4.2%).

Because lower levels of education are associated with poor birth outcomes, CDC compared maternal education levels of women who gave birth in 2000. The analysis indicates that women born outside the 50 states and DC were more than twice as likely as their state-born racial/ethnic counterparts to have less than a high school education (38.9% versus 17.0%) and were less likely to have completed 12 years of education (26.2% versus 33.4%). Approximately 59% of Hispanic women born outside the 50 states and DC had less than a high school education compared with 33.4% of state-born Hispanic women. State-born API women did not differ significantly from API women born outside the 50 states and DC in having less than a high school education (11.7% versus 11.3%). However, Chinese women born outside the 50 states and DC were four times as likely as their state-born counterparts to have less than a high school education (12.5% versus 2.9%). State-born women overall, state-born API women, and state-born Hispanic women were more likely than those born outside the 50 states and DC to have completed ≥1 year of college. Puerto Rican, white, black, Filipina, and other API women† born outside the 50 states and DC were more likely than their state-born counterparts to have completed college.

State-born women were more likely than those born outside the 50 states and DC to be teenagers when they gave birth (12.8% versus 8.1%). The magnitude of the difference varied by race/ethnicity, with the largest intragroup differences occurring among other APIs (19.7% versus 2.8%), blacks (21.5% versus 5.8%), and Filipinas (13.2% versus 3.1%). State-born women were more likely to be unmarried than those born outside the 50 states and DC (34.1% versus 29.7%). This finding was consistent across all racial/ethnic groups, with the largest intragroup differences occurring among blacks (72% versus 41%), Filipinas (34.4% versus 16.1%), and whites (22.7% versus 10.7%). Except for Puerto Ricans, Cubans, Filipinas, and other APIs, women born outside the 50 states and DC were more likely than their state-born counterparts to begin prenatal care late or to have no prenatal care.

Overall, state-born women were more likely to give birth to a preterm infant (11.9% versus 10.5%) or an infant with low birthweight (7.9% versus 6.4%) than were those born outside the 50 states and DC. For preterm delivery, this finding was consistent for all racial/ethnic populations except Filipinas, Cubans, and Central/South Americans born outside the 50 states and DC. Among Mexicans, who comprised the largest group of Hispanics, the difference was 11.9% versus 10.5%. For low birthweight, this finding was consistent for all racial/ethnic groups except for Cubans and Puerto Ricans born outside the 50 states and DC. The largest intragroup difference occurred between state-born blacks and those born outside the 50 states and DC, for both preterm births (17.8% versus 14.0%) and low birthweight (13.5% versus 9.8%). The preterm difference among Mexicans was 6.8% versus 5.5%.

B Sappenfield, MD, C Ferré, MA, S Iyasu, MMBS, Div of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion; JA Martin, MPH, SJ Ventura, MA, National Center for Health Statistics; DR Allen, PhD, EIS Officer, CDC.

Approximately one in five live births in the United States in 2000 were to women born outside the 50 states and DC. State-specific comparisons of the number and distribution of such births from 1990 and 2000 reveal a shift to states in the West and the South; births to Hispanic women accounted for most of this increase.

Overall, women born outside the 50 states and DC had better birth outcomes than their state-born racial/ethnic counterparts. Previous research has indicated similar differences, even after adjustment for differences in age, education, and marital status.^3- 4 Although better birth outcomes among immigrants might reflect a "healthy immigrant effect" (i.e., healthier persons might be more likely to immigrate), immigrant status also might serve as a proxy for various protective behavioral, cultural, and psychosocial factors that influence pregnancy outcome positively.³ For example, immigrants might have more extensive social support networks to draw upon during their pregnancies. The process of acculturation, which includes the adoption of new values, attitudes, and behaviors that affect health, such as tobacco use and pregnancies at an earlier age, might reduce these protective benefits and result in poorer pregnancy outcomes among immigrants over time.

An analysis of pregnancy-related mortality in the United States during 1991-1997 indicated an increased risk for maternal death among Hispanic and API immigrants compared with nonimmigrant whites.⁶ Although few studies have focused specifically on access to maternal health-care services among immigrant women in the United States, studies indicate that recent immigrants face various economic, cultural, and language barriers when trying to access health care.⁷ Recent epidemiologic investigations underscore the need for maternal and child health services that are responsive to changing immigration patterns. Studies have demonstrated an increased prevalence of congenital rubella syndrome among infants born to women who migrate from countries that have no mandatory rubella vaccination programs⁸ and an association between the consumption of raw milk products and poor pregnancy outcomes among a community of recent immigrants.⁹

The findings in this report are subject to at least two limitations. First, how race/ethncity and mother's place of birth are reported might vary between 1990 and 2000. Second, caution should be used when comparing some reported estimates because of the small numbers of births in some states and among some racial/ethnic populations.

This report highlights the need for U.S. maternal health services to adapt to changing immigration patterns by providing culturally competent maternal and child health services to an increasingly diverse population. Such services should include language interpretation; cross-cultural training to increase health practitioners' awareness of the impact of health beliefs, cultural practices, and perceptions of health risks on health outcomes; and programs that educate patients to access care and participate in treatment decisions.^2,10

*This terminology is used instead of "foreign-born" because persons who were born in U.S. territories and in Puerto Rico are U.S. citizens and thus by definition are not "foreign-born."

†"Other API women" include Asians/Pacific Islanders other than Chinese, Japanese, and Filipinas (e.g., Asian Indians, Koreans, and Vietnamese).