PLASMA FERRITIN AND PREGNANCY OUTCOME

OBJECTIVE: Plasma ferritin is considered the best measure of total bod y iron, with low levels diagnostic of iron deficiency. High levels hav e been associated with inflammation and infection. We determined the r elationship between plasma ferritin, birth weight, and preterm deliver y. STUDY DESIGN: Plasma ferritin and hematocrit values were measured a t 19, 26, and 36 weeks' gestational age and correlated with birth weig ht and preterm delivery (less than or equal to 32 and <37 weeks) in 58 0 indigent black women. RESULTS: Hematocrit levels measured at any ges tational age did not correlate significantly with birth weight or pret erm delivery. Regardless of the gestational age of sampling, ferritin levels in the lowest quartile did not correlate significantly with sub sequent preterm delivery. However, at 26 weeks, compared with the thre e lower quartiles, ferritin levels in the highest quartile were signif icantly associated with preterm delivery less than or equal to 32 week s, 6.5% versus 2.3% (p = 0.02), with preterm delivery <37 weeks, 14% v ersus 8% (p = 0.04), and with birth weight <1500 gm, 6.5% versus 2.0% (p = 0.01). Plasma ferritin levels in the highest quartile at 19, 26, and 36 weeks were associated with birth weight less than or equal to 2 500 gm, 14% versus 8% (p = 0.03), 12% versus 7% (p = 0.05), and 10% ve rsus 2% (p = 0.0001), respectively compared with the lower quartiles. Ferritin levels in the highest quartile were always associated with a lower mean birth weight than were those in the lower three quartiles: 19 weeks, 2999 gm versus 3225 gm, (p = 0.002); 26 weeks, 3065 gm versu s 3257 gm, (p = 0.005); and 36 weeks, 3182 gm versus 3323 gm, (p = 0.0 09). Regression analyses controlling for multiple potential confounder s confirmed that at 26 weeks ferritin levels in the highest quartile h ad an odds ratio and 95% confidence interval for preterm birth <37 wee ks of 2.0 (1.1 to 3.8), preterm delivery less than or equal to 32 week s of 2.7 (0.99 to 7.6), birth weight less than or equal to 1500 gm of 3.9 (1.2 to 12.2), and birth weight less than or equal to 2500 gm of 2 .0 (1.0 to 4.0) compared with the three lower ferritin quartiles. CONC LUSION: High, but not low, plasma ferritin levels, especially at 26 we eks, were strongly associated with subsequent preterm delivery and bir th weight.