In the US, the majority of deaths and serious complications of pregnancy occur during childbirth and are largely preventable. We conducted a population-based study to assess disparities in maternal health between Mexican-born and Mexican-American women residing in California and to evaluate the extent to which immigrants have better outcomes. Mothers in these two populations deliver 40% of infants in the state. We compared maternal mortality ratios and maternal morbidities during labour and delivery in the two populations using linked 1996–98 hospital discharge and birth certificate data files. For maternal morbidities, we calculated frequencies and observed and adjusted odds (OR) ratios using pre-existing maternal health, sociodemographic characteristics and quality of health care as covariates.
Approximately 19% of Mexican-born women suffered a maternal disorder compared with 21% of Mexican-American women (Observed OR = 0.89, [95% CI 0.88, 0.90]). Despite their lower education and relative poverty, Mexican-born women still experienced a lower odds of any maternal morbidity than Mexican-American women, after adjusting for covariates (OR = 0.92, [95% CI 0.90, 0.93]). These findings suggest a paradox of more favourable outcomes among Mexican immigrants similar to that found with birth outcomes. Nevertheless, the positive aggregate outcome of Mexican-born women did not extend to maternal mortality, nor to certain conditions associated with suboptimal intrapartum obstetric care.