All pregnant women with a gestational age of 12 to 20 weeks, who had lived in Narathiwat province for at least one year prior to the study and had attended their first
antenatal visit in one of the study hospitals during January-December 2008, were included in the study. High risk pregnancies such as severe anemia of less than seven gm/dl, heart disease, AIDS, or any mental problems were criteria for exclusion.