Birthweight outcomes among Asian American and Pacific Islander subgroups in the United States

Background. Information on birth outcome among the Asian and Pacific Islander populations in the US is limited. This report examines the risks of moderately low (MLBW) and very low birthweight (VLBW) among six Asian subgroups (Chinese, Japanese, Filipinos, Asian Indians, Koreans, Vietnamese) and three Pacific Islander subgroups (Hawaiians, Guamanians, Samoans) as compared with non-Hispanic whites. Methods. Data from the 1992 US Natality File were used to calculate the percentage of MLBW and VLBW births among each Asian American and Pacific Islander subgroup. Logistic regression was used to calculate odds ratios (OR) after adjustment for maternal characteristics. Results. VLBW OR ranged from 0.75 among Chinese to 1.59 among Asian Indians. MLBW OR ranged from 0.89 among Samoans to 2.12 among Asian Indians. Adjusted OR increased for most Asian American groups (e.g. VLBW OR=1.89 for Asian Indians) and decreased among Pacific Islander subgroups, indicating relatively favourable risk characteristics for Asian Americans and unfavourable characteristics for Pacific Islanders. Risk of VLBW was not necessarily related to risk of MLBW. For instance, the VLBW OR among Japanese was 1.07, compared to an MLBW OR of 1.47. Conclusions. Marked heterogeneity in birthweight outcome was observed between Asian American and Pacific Islander subgroups. This heterogeneity was not related to traditional demographic risk factors. Additionally, risks of VLBW and MLBW were not always related. These findings suggest that the Asian American and Pacific Islander populations should not be aggregated into a single category, and that traditional measures of risk and birth outcome may not be valid for those groups.