Maternal, Pregnancy, and Birth Characteristics of Asians and Native Hawaiians/Pacific Islanders --- King County, Washington, 2003--2008

In 1997, the Office of Management and Budget issued revised standards for reporting race and ethnicity in federal datasets (1). In addition to permitting the reporting of two or more races for each record, the revised standards separated the "Asian or Pacific Islander" category into two categories: "Asian" and "Native Hawaiian or other Pacific Islander" (NHPI). To quantify the health status of NHPI mothers and infants in King County, Washington, 2003--2008 vital statistics for NHPI disaggregated from Asians were used to assess several key maternal and birth outcome indicators. This analysis determined that, compared with Asians in King County, NHPI mothers were significantly more likely to be adolescents, overweight or obese before pregnancy, or to have smoked during pregnancy, and their infants were more likely to be born preterm, weigh >4,500 g, or receive either third trimester only or no prenatal care. These results identify important differences and support routine presentation of health data separately for Asians and NHPIs.

To conform to the federal standards for collecting and reporting data on race and ethnicity (1), the Washington State Department of Health (DOH) adopted the 2003 revision of the U.S. Standard Certificate of Live Birth (2). Using the new reporting categories, the person completing the data collection form can check one or more races to indicate which the mother considers herself to be. Following the standards, DOH reports data for Asians and NHPIs separately. Under federal guidelines (1), Asian refers to a person having ancestral origins in any of the original peoples of the Far East, Southeast Asia, or the Indian subcontinent (e.g., Cambodia, China, India, Japan, Korea, Malaysia, Pakistan, the Philippine Islands, Thailand, or Vietnam). NHPI refers to a person having origins in any of the original peoples of Hawaii, Guam, Samoa, or other Pacific Islands (including Fiji, Tonga, Micronesia, Melanesia, French Polynesia, Palau, the Northern Mariana Islands, and the Marshall Islands). Information on birth weight, length of gestation, maternal prepregnancy height and weight, initiation of prenatal care, maternal age, and smoking status during pregnancy are collected on the birth certificate.

The DOH birth certificate statistical file was used to calculate population health measures of maternal characteristics and birth risk factors for Asians and NHPIs in King County. Comparisons were made using a Pearson chi-square test. All persons identified as only Asian race or as multiple races that included Asian as one of the races were included in the Asian category. Similarly, single and multiracial persons identified as only NHPI or as NHPI in combination with another race were included in the NHPI reporting category. Prevalences are presented for single race and multiracial persons combined because of identification as a single community. However, multiracial persons reporting both Asian and NHPI race were excluded from this analysis. Self-reported height and weight data were used to calculate prepregnancy body mass index (BMI) (weight [kg] / height [m2]). Respondents were considered overweight if their BMI was 25.0--29.9 and obese if their BMI was ≥30.0. Infants were considered preterm if born at <37 completed weeks of gestation. Prenatal care initiation in the third trimester was considered to be late initiation.

Washington had the third-largest NHPI community in the United States (43,000 single or multiracial NHPI persons), after Hawaii (283,000) and California (221,000), according to U.S. Census counts for 2000 (3). Approximately 22,000 NHPI and 303,000 Asian single race and multiracial persons lived in King County in 2009, based on U.S. Census Bureau estimates.*

Combining data from 2003--2008, King County recorded 142,350 births, of which 2,442 were to NHPI mothers (79.2% NHPI only and 20.8% NHPI in combination with another race). During that period, 26,229 births in the county were to Asian mothers (92.4% Asian only and 7.6% Asian in combination with another race). A total of 242 births were to multiracial women who considered themselves to be both Asian and NHPI and were excluded from further analyses.

In King County, NHPI mothers were significantly more likely than Asian mothers to be overweight (23.9% versus 19.5%; p<0.001) or obese (49.9% versus 7.6%; p<0.001) before pregnancy. NHPI mothers also were more likely than Asian mothers to smoke during pregnancy (9.8% versus 1.4%; p<0.001) or to be adolescents (aged 15--17 years) (2.4% versus 0.6%; p<0.001). Infants born to NHPI mothers were significantly more likely than infants of Asian mothers to be born preterm (12.6% versus 9.7%; p<0.001), at high birth weight (>4,500 g) (3.0% versus 0.6%; p<0.001), or to have received either late or no prenatal care (15.8% versus 4.2%; p<0.001). No significant differences were observed for very low birth weight (<1,500 g; p=0.2), and infants of Asian mothers were more likely to be born at low birth weight (<2,500 g; p<0.001) (Table).

Reported by

EY Wong, PhD, D Solet, PhD, Assessment, Policy Development, and Evaluation Unit, Public Health--Seattle & King County, Washington.

Editorial Note

Although the 1997 revised federal guidelines on collection of race/ethnicity data separated the "Asian or Pacific Islander" race categories, many published analyses have continued to present data for the combined Asian/Pacific Islander group rather than present data separately for Asians and NHPIs. Differences between NHPIs and Asians resulting from cultural heterogeneity between these groups, variations in income and poverty, and historical discrimination and immigration patterns support routine disaggregation of health data for these racial groups in public health planning and reporting of data (4). The results of this analysis quantify important health concerns among the NHPI population in King County and support wider reporting of the new race categories for population-level health indicators.

Because the King County Asian population is approximately 10 times larger than the NHPI population, separate reporting categories are critical to accurately assess local NHPI population health and identify disparities. In King County, the prevalence of high infant birth weight, preterm births, and late or no initiation of prenatal care was higher among NHPI mothers than Asian mothers. NHPI mothers also were more likely to be overweight or obese before pregnancy, to be adolescents, or to have smoked during pregnancy. Identification of such health disparities in the local NHPI population is critical for validating community concerns and developing local programs to address health problems.

NHPI maternal and child health indicators differ from those for Asians, not only in King County, but also in other geographic areas. A limited number of prior studies, mainly from Hawaii and California, have identified elevated risks for preterm birth (5,6), low birth weight (5,6), high birth weight (5), smoking during pregnancy (5), and teen births (5,7) among Pacific Islanders. High birth weight might be influenced by high rates of obesity and diabetes (8). A high prevalence of either third trimester initiation or a complete lack of prenatal care during pregnancy might be caused by more frequent logistical, financial, and personal barriers to early prenatal care access (9).

Although this report focused on maternal and child health indicators, important health disparities among NHPIs can be identified for other vital statistics (e.g., deaths), adverse health outcomes, and health risk behaviors (e.g., smoking and unhealthy weight) (8). Data for these other population health measures are of high interest, but are outside the scope of this report.

The findings in this report are subject to at least four limitations. First, differences in maternal and child health indicators have been identified not only between Asians and NHPIs, but also within Asian and NHPI reporting categories (6,7,9) and among single and multiple race persons (6). Further analyses by subgroup will be needed to design appropriate programs and to describe disparities accurately. Second, this report presents data combined for the 2003--2008 period to provide precise prevalence estimates. Any underlying trends during this period might be masked by using combined data. Third, these analyses did not consider the role of potential confounders, which might affect the differences in maternal, pregnancy, and birth characteristics reported between Asian and NHPI women. Finally, the heterogeneity of local populations might affect the generalizability of these findings to other areas and nationally.

At the end of 2009, a total of 32 states and the District of Columbia reported birth certificate data with disaggregated race information (2). The findings in this report support the use of separate Asian and NHPI data collection categories by other states. This would allow federal and local agencies to report disaggregated data. Without key assessment data describing health disparities between racial groups, public health agencies and community partners cannot accurately and efficiently design and implement policies and programs to address national public health priorities.

Acknowledgments

This report is based, in part, on contributions by M Ro, L Alfonsi, B Lacet, M Smyser, M Valenzuela, Public Health--Seattle King County; M Taualii, Urban Indian Health Institute, Pacific Islander Women's Association; and the Native Hawaiian and Pacific Islander community of King County, Washington.

References

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2. Hamilton BE, Martin JA, Ventura SJ. Births: preliminary data for 2009. Natl Vital Stat Rep 2010;59(3).
3. Grieco EM. The Native Hawaiian and other Pacific Islander population: 2000. Washington, DC: US Census Bureau; 2001. Available at http://www.census.gov/prod/2001pubs/c2kbr01-14.pdf. Accessed February 17, 2011.
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8. Asian and Pacific Islander American Health Forum. Native Hawaiian and Pacific Islander health disparities. San Francisco, CA: Asian and Pacific Islander American Health Forum; 2010. Available at http://www.apiahf.org/index.php/component/content/article/818.html. Accessed February 15, 2011.
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