The effect of acculturation on progesterone/estriol ratios and preterm birth in Hispanics

OBJECTIVE: To examine the Hispanic acculturation paradox by identifying the effect of acculturation on serum progesterone and estriol levels, the progesterone/estriol ratio, and preterm birth. METHODS: We used an observational, prospective design with 468 self-identified, low-income, pregnant Hispanic women. We used the Language Proficiency Subscale (from the Bidimensional Acculturation Scale for Hispanics) to measure acculturation. We measured progesterone and estriol in maternal serum at 22-24 weeks of pregnancy. We defined preterm birth as birth before 37 weeks of gestation. Statistical analysis was by Wilcox-Mann-Whitney and Kruskal-Wallis tests, analysis of variance, t tests, logistic regression,. and structural equation modeling. RESULTS: English proficiency had an adjusted odds ratio of 4.03 (95% confidence interval 1.44-11.25), P<.001, and the lowest quartile of the progesterone/estriol ratio had an adjusted odds ratio of 2.93 (95% confidence interval 1.25-6.89), P<.001, to predict preterm birth. English proficiency was associated with a decrease in progesterone/estriol ratio and an increase in preterm birth. In structural equation modeling, the progesterone/estriol ratio mediated the relationship between acculturation and preterm birth. CONCLUSION: Hispanic woman have four times the risk of a preterm birth if they are more acculturated (ie, proficient in English). These findings demonstrate another possible aspect of obstetric risk, that of acculturation. Further refinement of the risk of acculturation is essential to clarify how we can adjust our clinical care to prevent increasing preterm birth with the increasing Hispanic population.