Mexican women in California: differentials in maternal morbidity between foreign and US-born populations

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.