Uninsured Mothers and the Increased Risk of Poor Birth Outcomes: Do Biochemical Markers Play a Role?

Context: About 20% of the US population lacks health insurance. Epidemiological data show that pregnant women without medical insurance have poorer birth outcomes.

Objective: This study compares blood levels in insured vs. uninsured women of biochemical markers known to affect birth outcomes to determine whether differences can explain the poorer outcomes. Types of insurance and demographic variables were evaluated for confounding.

Design: All women of reproductive age in NHANES 1999-2002 (a representative sample of the U.S. population) with data on health insurance status and selected biochemical markers (n = 3,540) were included in this cross sectional study.

Outcome Measures: Maternal mean RBC folate, serum iron, and total serum mercury.

Results: Demographics associated with poorer outcomes were: age (<18 years and >40 years), marital status (unmarried), income (<$4,000), education (< high school) and race/ethnicity (non-Hispanic whites). Controlling for these confounders, the mean folate level (ng/mL) was 286.7 for the insured group and 274.6 for the uninsured group (p = 0.02). The mean iron level (ug/dl) was 85.5 for the insured group and 78.7 for the uninsured group (p = 0.01). Mercury showed no statistically significant difference between the groups. Women with Medicaid had a significantly lower level of folate than women with private insurance or uninsured women (p < 0.01).

Conclusions: Mean serum folate and iron levels are lower in uninsured women vs. insured women after controlling for demographic confounders. This difference may partially explain the poorer birth outcomes in uninsured women vs. insured women.