The primary aim of this study is to determine how prenatal exposure to malaria influences development of humoral and cellular immune responses to malaria blood stage antigens from birth to 3 years of age. In addition, the study will determine the risk factors and mechanisms associated with congenital malaria or exposure of the fetus to malaria blood stage antigens, assess how prenatal exposure to malaria affects susceptibility to malaria infection during infancy, and evaluate how perinatal exposure to malaria affects growth and development during infancy. A primary goal of this research will be to examine a cohort of infants from birth to 36 months of age; the predictive value of allele-specific invasion inhibitory antibodies to Merozoite Surface Protein 1 (MSP1) and antibody titers to MSP1 will be evaluated with respect to type and magnitude of neonatal cellular and humoral immune response to MSP1. An understanding of natural immunity to MSP1, and the influence of prenatal exposure, may be critical to informed interpretation of immunologic, parasitologic, and clinical endpoints of vaccine trials using blood stage antigens that will be ultimately directed to infants and children. Healthy adult pregnant women (greater than or equal to 15 years of age) and their healthy offspring (beginning at birth) will be followed until they are 36 months old. Newborns will be examined at birth and at 6, 12, 18, 24, 30 and 36 months of age. Enrollment will occur at time of first visit to the antenatal clinic during the second trimester when peripheral blood, stool, and urine samples will be obtained from each pregnant woman. A finger stick blood sample will be obtained from the mothers at each subsequent antenatal visit to assess the presence of malaria during pregnancy. An ultrasound examination will be done on the mothers at the initial antenatal visit to assess gestational age and at 26-30 weeks to assure proper growth and development of fetus and to screen for any potential problems. At delivery venous and finger stick blood, stool, and urine will be obtained from the mother. Umbilical cord and placental blood, and a placental biopsy will be obtained, and thereafter infants will be followed every 6 months (plus or minus 2 months). A physical examination of infants will be done and peripheral blood, stool, and urine will be obtained from infants. The study population will also include about 20 healthy adult North American control subjects with no malaria exposure or infection and about 40 adult Kenyans who either have been exposed to malaria or have asymptomatic malaria infection.