Material and Methods
This study was conducted retrospectively with women who had delivered at a high-volume tertiary care center between July 2014 and January 2015. Our study was performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki, and the research protocol was approved by the Ethics Committee of our center. Informed consent was obtained from all participants. The study population consisted of singleton pregnancies that delivered between 37 and 42 weeks of gestation and were monitored in the obstetric unit of our center after delivery. Chronic diseases leading to anemia such as renal, cardiac, and lung diseases and hemoglobinopathy were excluded. The minimum sample size required for this study was estimated by assuming a confidence interval of 95%, a 5% margin of error, and a prevalence of 32.6% for anemia among pregnant women. Accordingly, the minimum sample size required for the study was 333. A total of 1221 women were enrolled in the study, and all of them were recruited to increase the power of the study.
Before discharge, all the women who had delivered were interviewed using a questionnaire to collect their socioeconomic and demographic data. Furthermore, the following information was obtained from the computerized medical record system of our hospital: hemoglobin value within 24 h prior to delivery, maternal age, number of parity and abortus, body mass index before pregnancy, weight gain during pregnancy, educational level, occupational status, household monthly income per person, smoking habit, alcohol consumption, number of antenatal care visits, number of ultrasonography examinations done during pregnancy, gestational age at first admission, gestational age at delivery, and duration of iron and folic acid supplementation. Household monthly income per person was calculated as the total household monthly income divided by the total number of family members living together. Adverse perinatal outcomes were recorded as dichotomous variables (yes or no) and included antenatal bleeding, hypermesis gravidarum, placenta previa, gestational diabetes, preeclampsia, intrauterine growth restriction, and congenital anomalies. We categorized patients into two groups according to the presence or absence of anemia within 24 h before the onset of delivery. Anemia was defined as a hemoglobin level of