Figure 1.

Superoxide (${\text{O}}_2{\hspace{0.17em}}^{•-}$) levels (means and standard errors of the means) over time for maternal–fetal medicine (▴: MFM) and general obstetrics practice (▪: GOP) groups. Changes over time were significant for ${\text{O}}_2{\hspace{0.17em}}^{•-}$ levels in MFM pregnancies, χ²(4) = 12.8, p = .012, with a trend toward a significant difference from the 12–20 weeks and the umbilical cord time points (z = −2.72, p = .06). There were no significant changes over time in the GOP pregnancies. Reported p values for the pairwise comparisons include the Bonferroni correction.