Effect of Maternal Cigarette Smoking on Newborn Iron Stores.

Background: Maternal smoking has been known to have a negative impact on the well being of the developing fetus. Prenatal smoking has been associated with premature births, low birth weight and with certain birth defects. Small research studies have also found a negative correlation between maternal smoking and neonatal body iron.

Objectives: To study and compare the relationship between maternal and infants' body iron in smokers and non-smokers in a large matched-pair cohort.

Methods: This was a prospective cohort study involving 144 mothers - 72 smokers and 72 non-smokers and their respective infants. Samples were obtained from maternal and infants' cord blood at delivery for Serum transferrin receptor (sTfR) and ferritin levels. Serum TfR and ferritin were measured by RAMCO ELISA and RIA assays. Total Body Iron (TBI) was calculated using the sTfR/ferritin ratio in a previously described formula by Cook et al.

Results: Women who smoked had lower sTfR, higher ferritin and higher body iron compared to nonsmoking women. In contrast to their respective mothers, we found a small, but statistically significant negative correlation between smoking and infants' total body iron. The number of packs per day smoked was also negatively correlated with infants' ferritin and total body iron. Lower birth weight was noted in babies of smokers compared to nonsmokers (mean /- SD =3270 +/-475 vs. 3393 g +/- 475 g, p=0.03).

Conclusion: Women who smoked during pregnancy had higher iron stores but their newborn infants had lower iron stores than those of non-smoking mothers. The more packs per day (PPD) and more days smoked during pregnancy led to lower total body iron of the babies. There may be a negative dose-dependent response between fetal smoke exposure and infant iron stores.