The purpose of this study is to identify the influences of pregnancy on breast milk and the effects of these on the health of babies during the first 2 months of life. The investigators hypothesize that overweight and obese mothers will have lower serum n-3 to n-6 PUFA ratios during pregnancy and postpartum than normal weight mothers and will be positively correlated with TNF-α, IL-1β, resistin, and negatively correlated ghrelin levels both in serum and in breast milk in postpartum.