Association of Acculturation With Adverse Pregnancy Outcomes.

Objective: To evaluate the relationship between acculturation and adverse pregnancy outcomes, and whether these relationships differ across racial or ethnic groups.

Methods: This is a planned secondary analysis of the nuMoM2b study (Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be), a prospective observational cohort study of 10,038 pregnant women at eight academic health care centers in the United States. Nulliparous pregnant women with singleton gestations were recruited between 6 0/7 and 13 6/7 weeks of gestation from October 2010-September 2013. Acculturation was defined by birthplace (United States vs non-United States), language used during study visits (English or Spanish), and self-rated English proficiency. The adverse pregnancy outcomes of interest were preterm birth (less than 37 weeks of gestation, both iatrogenic and spontaneous), preeclampsia or eclampsia, gestational hypertension, gestational diabetes, stillbirth, small for gestational age, and large for gestational age. Multivariable regression modeling was performed, as was an interaction analysis focusing on the relationship between acculturation and adverse pregnancy outcomes by maternal race or ethnicity.

Results: Of the 10,006 women eligible for this analysis, 8,100 (80.9%) were classified as more acculturated (eg, born in the United States with high English proficiency), and 1,906 (19.1%) were classified as having less acculturation (eg, born or not born in the United States with low proficiency in English or use of Spanish as the preferred language during study visits). In multivariable logistic regression modeling, more acculturation was significantly associated with higher frequency of preterm birth (odds ratio [OR] 1.46, adjusted odds ratio [aOR] 1.50, 95% CI 1.16-1.95); spontaneous preterm birth (OR 1.54, aOR 1.62, 95% CI 1.14-2.24); preeclampsia or eclampsia (OR 1.39, aOR 1.31, 95% CI 1.03-1.67); preeclampsia without severe features (OR 1.44, aOR 1.43, 95% CI 1.03-2.01); and gestational hypertension (OR 1.68, aOR 1.48, 95% CI 1.22-1.79). These associations did not differ by self-described race or ethnicity.

Conclusion: In a large cohort of nulliparous women, more acculturation, regardless of self-described race or ethnicity, was associated with increased odds of several adverse pregnancy outcomes.

Clinical Trial Registration: ClinicalTrials.gov, NCT01322529.