Department of Obstetrics and Gynaecology, Gazi University Faculty of Medicine, Ankara, Turkey.
East Mediterr Health J. 2020 Oct 13;26(10):1227-1232. doi: 10.26719/emhj.20.021.
Iron deficiency is the most common cause of anaemia in pregnancy. Guidelines recommend different threshold values for iron supplementation.
To determine trimester-specific reference ranges for haematological values (haemoglobin, hematocrit and ferritin) in healthy pregnant women who have not used any iron supplementation during pregnancy to guide future iron treatment.
A prospective cross-sectional study was carried out on 168 pregnant women aged 18-45 years, with singleton pregnancies in the first trimester, Hb ≥ 11 g/dL and ferritin ≥ 12 μg/L, and not using iron supplementation. Multiple pregnancies, pregnancies with obstetric complications and smokers were excluded from the study. Mean haemoglobin (Hb) and ferritin values, trimester-specific reference ranges and percentile values of Hb and ferritin were determined for each trimester. The normality of the variables was tested using the Kolmogorov-Smirnov test.
Mean Hb decreased significantly between trimesters from 12.6 to 11.9 and then 11.5 g/dL. In addition, Hb, hematocrit and ferritin decreased significantly from the first to the second trimester (P < 0.001 for all) but stayed comparable between the second and third trimesters (P = 0.246, P = 0.575, P = 0.408, respectively). The lower reference value for Hb was calculated as 10.67, 10.08 and 9.18 g/dL for 10-14, 20-24 and 30-34 gestational weeks respectively.
This pioneer study allows us to understand that iron supplementation may not be needed as any decrease is due to physiological haemodilution. These results may prevent unnecessary iron prescription during pregnancy.
缺铁是妊娠贫血最常见的原因。指南建议针对铁补充的不同阈值。
确定未在妊娠期间使用任何铁补充剂的健康孕妇在妊娠期间特定孕期的血液学值（血红蛋白、血细胞比容和铁蛋白）参考范围，以指导未来的铁治疗。
对 168 名年龄在 18-45 岁之间、初孕期 Hb≥11g/dL 和铁蛋白≥12μg/L、且未使用铁补充剂的单胎妊娠孕妇进行前瞻性横断面研究。排除多胎妊娠、产科并发症和吸烟者。确定每个孕期的平均血红蛋白（Hb）和铁蛋白值、孕期特异性参考范围和 Hb 和铁蛋白的百分位数值。使用 Kolmogorov-Smirnov 检验测试变量的正态性。
平均 Hb 从 12.6 降至 11.9，再降至 11.5g/dL，各孕期间显著下降。此外，Hb、血细胞比容和铁蛋白从第一孕期至第二孕期显著下降（所有 P<0.001），但第二孕期与第三孕期间无差异（P=0.246、P=0.575、P=0.408）。Hb 的较低参考值分别计算为 10.67、10.08 和 9.18g/dL，适用于 10-14、20-24 和 30-34 孕周。
这项开创性研究使我们能够理解，可能不需要补充铁，因为任何下降都是由于生理血液稀释。这些结果可能有助于避免在妊娠期间不必要的铁剂处方。
