Depression after pregnancy is called postpartum depression and may be caused by a rapid change in hormone levels during and immediately after pregnancy. Researchers believe that it is one of the most common complications linked to pregnancy. This type of depression occurs in 10 to 15% of women within the first 3 months of giving birth and it can negatively affect both mothers and their children. Mothers with postpartum depression may experience low energy, difficulty concentrating, irritability, and inability to meet their children's needs for love and affection. Research shows that children of mothers with postpartum depression may have delays in language development, difficulty with emotional bonding to others, behavioral problems, lower activity levels, sleep problems, and distress. Many women who have suffered from postpartum depression in the past are worried about a repeat episode with the birth of their next baby. This study will determine the effectiveness of taking sertraline within 24 hours of giving birth in preventing a recurrence of postpartum depression.