Introduction
Worldwide, iron deficiency is the most common nutritional deficiency(1,2). Approximately 20% of pregnant women worldwide
suffer from anaemia due to this(3).
During pregnancy, iron deficiency risk increases due to the requirement
of additional iron to sustain the expansion of red cell mass, and the
growth of the fetus and placenta(1). Iron deficiency
contributes to adverse pregnancy outcomes such as intrauterine growth
retardation and perinatal death(4,2). Some studies
have shown maternal iron deficiency at delivery to be associated with
lower serum ferritin levels in the cord blood of neonates, especially
when the mother’s serum ferritin level was below 13
μg/l(5,6,7). This perhaps explains why iron deficiency
impacts fetal and infant well-being by affecting brain development,
auditory neural maturation, and increasing the risk of poorer cognitive,
motor, social-emotional, and neurophysiologic
development(4,8,9).
Iron deficiency is progressive: iron stores in the body gradually
diminish, resulting in iron deficiency anaemia
(IDA)(5,10). Latent iron deficiency (LID) occurs when
iron stores are exhausted but the blood haemoglobin (Hb) levels are
within normal limits(11). Hence women with LID are at
a higher risk of developing IDA – associated with pregnancy
complications, if not for early detection and treatment.
Assessment of Hb level alone, however, is not adequate to identify
LID(12). Estimation of serum ferritin is the more
pertinent method to detect body iron stores(5,13),(5). A serum ferritin level of <30 ug/l in
pregnancy is considered as LID(5). Even though serum
ferritin is currently available in most general hospitals in Sri Lanka,
it is an expensive test and is not performed routinely. Therefore,
surrogate screening tests are needed to identify women with LID.
In LID, the mean corpuscular volume (MCV) usually remains within normal
limits, but a few microcytes may be detected on a blood
smear(14). Therefore, increased red cell distribution
width (RDW) may be an early indicator for LID(15,16).
Red cell indices and RDW are low-cost investigations included in the
full blood count (FBC), which can be undertaken in hospitals in Sri
Lanka and other developing countries.
The prevalence of LID among pregnant women in Sri Lanka is currently not
well known. Better awareness would enable clinicians to act within the
routine antenatal care plan. Thus, the primary objective of this study
was to assess the prevalence of LID in early pregnancy. Furthermore, the
secondary objective was to identify LID using red cell indices, RDW, and
blood films as surrogate screening tools.