At 17, 24, 30, and 36 weeks of pregnancy small blood samples will be collected from their arm (approximately one tablespoon at each collection) for laboratory analyses. At the birth of their baby a sample of blood will be collected from the umbilical cord after their baby is delivered. All blood samples will be stored at Pennington Biomedical. Blood samples will be analyzed by the researchers who are involved in the study. Some analyses will take place at Pennington Biomedical and Louisiana State University (LSU). Deidentified (without subject names) samples will be sent to study researchers at Northeastern University in Boston, LSU Health Sciences Center in New Orleans, and DSM Nutritional Products in Columbia, Maryland for some of the analyses. At the end of the study remaining blood samples will be discarded unless women consent for their blood to be used for future research. Should women decide to withdraw from the study, any samples collected thus far will be included in the study since they will be deidentified and the investigators will not know which samples belong to each person. We will also collect information about the baby's birth weight, length, and health from the baby's hospital chart.