The main finding of our investigation is that private insurance did not benefit all race/ethnicity groups equally. Specifically, having private insurance did not protect Black/Non-Hispanic mothers. Black/Non-Hispanic mothers with private insurance had higher NICU admission odds among teenagers and intermediate group women than age-matched women with public insurance. From our data we can not determine whether our findings directly resulted from differences in health care provision based on insurance or whether insurance was a proxy for other important factors including absence of poverty. We speculate that the etiology of the paradoxical relationship of higher NICU admission odds among Black/Non-Hispanics with private insurance compared to public insurance is likely secondary to ecological experiences, which adversely affect the mother and are potentially exacerbated by higher socioeconomic status among certain minority groups. Our study is unique in investigating NICU admission, a variable indicative of physiologic instability of the newborn and a marker for long term health care utilization, in a large multicenter study sample.
Our data suggest that among Black/Non-Hispanic mothers, private health insurance, acting as a direct effect or proxy, does not mitigate the adverse effects of life-course stressors. This finding is consistent with other studies demonstrating a lack of protective effect from improved neighborhood characteristics and income on Black/Non-Hispanic birth outcomes.
These findings are consistent with other literature that shows a wider racial gap in poor birth outcomes among women at seemingly lower risk. A stark racial disparity in the unadjusted rates of preterm birth and very low birth weight exists among women with a lifelong residence in high-income urban neighborhoods
. It has also been reported that the positive effects of a better socioeconomic context may be mitigated among minority women by adverse effects of racism or racial stigma
. In addition, Black/Non-Hispanic infants in hyper segregated areas are more likely to be preterm than in non-hyper segregated areas
. Higher isolation has also been associated with lower birth weight, higher rates of prematurity and higher rates of fetal growth restriction, in contrast with higher clustering being associated with more optimal outcomes
. There are larger racial disparities among the non-poor than the poor in the black population and among women than men
Controlling the analysis for gestational age or limiting the study population to gestational age ≥ 35 weeks did not alter our findings. The lack of influence of gestational age on the findings suggests that the increased odds of NICU admission in this population are related to factors independent of premature birth. We speculate that Black/Non-Hispanic mothers with advanced age may have an increase in physiologic compromise that goes beyond the known increase in premature birth. These data are important in showing an increase in NICU admission possibly secondary to concomitant physiologic instability in infants born to Black/Non-Hispanic women. The study data provide further support of the “weathering hypothesis,” adverse maternal health may be secondary to persistent life course stressors that are not modifiable, and in fact may be exacerbated, with private insurance at the time of childbirth.
Hispanic women, when compared to the White/Non-Hispanic population, had decreased odds of NICU admission in the intermediate and advanced maternal age population for both private and public insurance. Hispanic women have lower odds for preterm birth compared to White/Non-Hispanic women. When compared to African-American women, Hispanic women are less likely than African-American women to experience any adverse pregnancy event
. Latina mothers in the United States have been shown to have favorable birth outcomes despite their social disadvantages. Proposed explanations for this can be classified as migratory selection processes, cultural protective factors, and increased social support
. There was an increased risk of NICU admission with AMA among Hispanic and White/Non-Hispanic in the public insurance group that was not seen in the private insurance group. This suggests that the “weathering hypothesis,” cumulative life course stressors affecting later health, may apply to White/Non-Hispanic and Hispanic mothers.
The results of this study were obtained without controlling for pregnancies conceived by assisted reproductive technology. Of approximately 62 million women of reproductive age in 2002, about 1.2 million, or 2%, had had and infertility related medical appointment within the previous year
. The risk of preterm birth is higher among infants conceived through assisted reproductive technology than for infants in the general population. This increase in risk is due, in large part, to the higher percentage of multiple-fetus pregnancies resulting from assisted reproductive technology cycles
. The influence of assisted reproductive technology would not be able to fully explain the differences seen due to small percentage of pregnancies conceived with this technology.
Our study has a number of important limitations. The CSLD may not be generalizable to other populations. This possibility was minimized as the database represents 19 hospitals in the United States from wide geographic regions and weighted to reflect national US nativity. Maternal insurance status may not correlate accurately with the actual socioeconomic level of each mother. There may have been other important factors influencing maternal health and wealth that we were unable to control for including maternal education level. The study also did not account for institutional policies and clinical biases that may have influenced NICU admission rates. We can not rule out the possibility that Black/Non-Hispanic mothers were more likely to deliver an infant in hospitals where NICU admission was more likely. In addition, we were only able to study insurance status at the time of birth. Length of private insurance coverage may be an important factor in estimating its effect on maternal health.
In our study, NICU admission was used as a primary outcome variable in order to investigate physiologic compromise and supplemental health care needs at birth. NICU admissions are not restricted to extremely premature infants or infants with congenital anomalies. Late preterm, term, and normal birthweight infants represent a significant percentage of NICU admissions and NICU-related health care costs
. In addition to the immediate health cost burden, NICU admissions are associated with increased risk for altered school-age behavior and achievement, accelerated development of health compromise, and reduced economic potential when becoming an adult. The daily NICU costs exceed $ 3,500 per infant, and it is not unusual for costs to top $ 1 million for a prolonged stay
. The annual societal economic burden associated with preterm birth in the United States was at least $26.2 billion in 2005, or $51,600 per infant born preterm