This research project is studying the causes for low platelet levels in preterm infants. Platelets are a component of blood that helps with clotting. The purpose of this study is to determine whether the cause for low platelet levels is the same in infants who are born to mothers with preeclampsia and infants who are small for gestational age.

Thrombocytopenia is a common entity in infants who are born to mothers with preeclampsia and in infants who are small for gestational age. There have been several theories to the mechanism underlying thrombocytopenia in these groups of patients. One mechanism suggests that thrombocytopenia in these populations may be secondary to underproduction of platelets. Other studies have implied that low platelet levels may be due to endothelial activation causing platelet consumption. This study is being performed to help determine the mechanism causing thrombocytopenia in infants born to mothers with preeclampsia and comparing it to the mechanism of thrombocytopenia in infants who are small for gestational age.

Inclusion Criteria:

• Infants who are less than 34 weeks gestation
• Infants born to mothers with preeclampsia
• Infants who are born small for gestational age whose mother did not have preeclampsia

Exclusion Criteria:

• Infants who are greater than 34 weeks gestation
• Infants with known congenital anomalies or known congenital infections

In utero infants who are small for gestational age or who are exposed to maternal pre-eclampsia