February 2001 - The Implications of Migration to the U.S. Mainland for Infant Mortality Among Puerto Ricans

 

It has been widely documented that foreign-born mothers of various ethnic backgrounds have better birth outcomes than their US-born counterparts. This has been attributed to the protective influence of the mother culture and the waning of that influence over time as migrants assimilate into the U.S. society. Selectivity in who migrates has also been offered as an explanation for the foreign- versus US-born differentials in birth outcomes. The contention being that migrants are more intelligent, healthy, and resourceful than the non-migrant peers they have left behind.

An NICHD/MCHB jointly supported investigation, Puerto Rican Maternal and Infant Health Study (PRMIHS), sought to test both of these assumptions using pooled vital statistics records and in person interviews, and based on a complex sample design that involved stratification by state, month, and birth outcome and the over sampling of infant deaths and low birthweight infants. Selected findings from the study are reported in an article entitled "Migration and Infant Death: Assimilation or Selective Migration Among Puerto Ricans?" that appeared in the December 2000 issue of the journal American Sociological Review (Vol. 65, pages 888-909). The authors of the article are: Nancy S. Landale, Ph.D., R.S. Oropesa, Ph.D., and Bridget K Gorman, Ph. D. from The Pennsylvania State University and the University of North Carolina at Chapel Hill.

Specifically, the PRMIHS: (1) compared the infant mortality rate of first- and second-generation Puerto Rican women residing in six states on the U.S. mainland (Connecticut, Florida, Massachusetts, New jersey, New York City, and Pennsylvania) with those of the offspring of women in Puerto Rico; (2) assessed the role of selective migration in producing the generational pattern of infant mortality observed for Puerto Rican women residing in the U.S.; and, (3) focused on the implications of the duration of the Puerto Rican mother's exposure to U.S. society for infant health as well as the mechanisms through which exposure was theorized to exert its effects. Testing of a series of logistic regression models with increasing number of explanatory and control variables characterized the statistical analyses part of the study.

Overall, findings from the PRMIHS study lend support to the waning cultural influence and selective migration hypotheses. The PRMIHS data indicate that both mainland-born women and long-standing mainland residents from Puerto Rico have higher rates of infant mortality than do recent migrants to the mainland. This pattern persists after controlling for an extensive set of demographic and socioeconomic variables. Findings also indicate that the risk of infant mortality is substantially lower among migrants with relatively few years of residence on the mainland than it is among women who remain in Puerto Rico. This latter finding enhances the validity of the selective migration hypothesis and undermines that of the protective culture one. If, argue the study investigators, beliefs and practices drawn from the origin culture are central to the favorable birth outcomes of migrants living on the mainland, then non-migrants at the origin should be similarly protected. That is not the case for the PRMIHS data. The data indicate that the risk of infant mortality for non-migrant Puerto Rican women is roughly similar to that for U.S. born mainland Puerto Rican women and considerably higher than that of recent migrant women.

Other interesting, mainly bivariate, findings reported by the study are: (1) education and income are unlikely to play key roles in explaining nativity differences in infant mortality among mainland Puerto Ricans; (2) those who live in a predominantly Latino neighborhood have higher risks of infant mortality than others, and; (3) participants of WIC program have a significantly lower rate of infant mortality than do non-participants.

A companion article focusing on the determinants of the use of prenatal care among the participants of the PRMIHS appear in the most recent issue of Social Science and Medicine (November 2000, Vol. 51, pages 1723-1739). Copies of both of these articles are available from the Research Program Office upon request: Telephone: (301) 443-2190, e-mail: rhaggerty@hrsa.gov.

 

Prepared by Gontran Lamberty

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