Methods
This cross sectional study was conducted in the obstetrics and
gynaecology units of North Colombo Teaching Hospital, Sri Lanka from
December 2014 to January 2017. All pregnant women with normal Hb levels
(≥110 g/l in <12 weeks, >105 g/l in 13-20 weeks
of gestation), booked for antenatal care within <20 weeks of
gestation, were the potential study subjects(5). Among
them, those with haematological diseases, active infections, liver
disease, chronic connective tissue disorders, malignancies, and
haemoglobinopathies were excluded(4). Written informed
consent was obtained from the selected subjects. Data were gathered from
interviews and antenatal records. The study was approved by the Ethics
Review Committee, Faculty of Medicine, University of Kelaniya, Sri
Lanka.
Blood samples were collected for FBC, blood film, and serum ferritin
level. Any further treatment or follow-up was in accordance with routine
clinical practice. Full blood count was analysed by a five-part Beckman
Coulter analyser, while serum ferritin was estimated by a two-step
immune metric technique. Blood film morphology was reported by three
independent observers. If a blood film showed features of the exclusion
criteria listed above, the subject’s data were excluded. Existing data
from a similar Sri Lankan population at the booking visit estimated the
LID to be 18%(10,17).
The sample size of the cross-sectional study was 355, calculated on the
basis of 4% acceptable difference at a 95% confidence interval. The
preliminary statistical analysis was limited to descriptive statistics.
IBM SPSS (version 16) was used for socio-demographic, FBC, and
morphology data analysis. Pearson’s chi squared test was applied to
determine statistical significance. The independent t-test analysed the
effect of prophylactic use of haematinics. Receiver Operating
Characteristic (ROC) curves were constructed to identify optimal cut off
values for red cell indices (4,12). Statistically significant P value
was taken as <0.05.