The role of prophylactic iron supplementation in pregnancy

Abstract

The prevalence, causes and role of iron prophylaxis in pregnant women was studied. All women delivered at the National University Hospital, Singapore in 1993 had their haemoglobin estimated. If it was less than 11 g/dl, blood was taken for serum iron, ferritin, transferrin, red cell zinc protoporphyrin, serum folate, vitamin B₁₂ and thalassemia screen to establish cause of anaemia. Data was also collected with regards to their antenatal progress and iron prophylaxis. Logistic regression, Chisquare test, Fischer's exact test and Mantel-Haenszel tests were also used to assess the relationships between categorical variables. The prevalence of anaemia at first antenatal visit was 20.6% while the prevalence of anaemia at delivery was 15.3%. The commonest cause of the anaemia in pregnancy was due to iron deficiency (81.3%). In the non-anaemic group, 90.7% were on prophylactic iron supplements compared to 50.6% in the anaemic group (P < 0.001). Of the 752 women found to be anaemic at booking, 591 received prophylactic iron supplements while 161 women did not. A total of 166 (28.1%) of those with iron supplements were anaemic at delivery, whereas 140 (87.0%) of those who did not receive prophylactic iron remained anaemic at delivery (P < 0.001). Of the 2516 non-anaemic women who received prophylactic iron, 118 (4.7%) developed anaemia at delivery while 133 (34.1%) out of the 390 women who did not receive prophylactic iron were anaemic at delivery (P < 0.001). Multivariate logistic regression analysis revealed the odds of anaemia for a woman not on iron therapy was about 11 times that of her counterpart on prophylactic iron therapy (95% CI 8.76 to 14.13). A 55% reduction in odds of anaemia was estimated per 1 gm% increase in haemoglobin at booking. Prophylactic antenatal iron supplements not only prevent a fall but also improved haemoglobin levels during pregnancy. Those who were not on any iron supplements were 11 times more likely to develop anaemia in the present pregnancy.