The understanding of the biological mechanisms underlying preterm birth is very limited, making prevention of preterm birth difficult. The incidence of preterm birth worldwide varies between 6% to 11% in singleton pregnancies and 64-93% of preterm deliveries occur after the spontaneous onset of labor (preterm labor) (1). The risk factors associated with preterm birth include demographic variables such as ethnic group, past obstetric history, and complications of the current pregnancy such as infection and fetal congenital anomalies. The current study aims to investigate the basic mechanisms of preterm labor by systematically cataloging the changes in expression levels of all expressed genes whose sequences are available. The goals will be accomplished by using microarray technology followed by subsequent confirmative or complementary analyses.

• INCLUSION CRITERIA:

Consecutive patients admitted with the following diagnoses from four different ethnic groups (Hispanic, African American, Asian, and Caucasian):

1. Preterm labor with intact membranes and with

   1. acute inflammation;
   2. chronic villitis;
   3. vascular pathology;
   4. no identifiable lesions.

2. Preterm delivery without labor because of the following reasons:

   1. pre-eclampsia;
   2. abruptio placentae;
   3. fetal anomalies;
   4. Other complications (e.g. automobile accidents) that necessitate immediate delivery.

3. PROM leading to preterm delivery and with

   1. acute inflammation;
   2. chronic villitis;
   3. vascular pathology;
   4. no identifiable lesions.
4. Term delivery without labor and no identifiable lesions.
5. Term delivery in spontaneous labor and no identifiable lesions.
6. Term delivery with chorioamnionitis.
7. Term delivery with failed labor leading to ceasarean section.

EXCLUSION CRITERIA:

1. Refusal of written informed consent
2. Fetal or maternal conditions mandating immediate delivery (i.e. fetal distress, significant hemorrhage, etc.)