• INCLUSION CRITERIA:

Gestational age between 6 and 22 weeks for the first visit.

High risk group: presence of specific risk factors for preterm delivery, pregnancy-induced hypertension or intrauterine growth retardation.

Low risk group: normal pregnancy with no risk factors for either preterm delivery, pregnancy-induced hypertension or intrauterine growth retardation (control population, selected between 6 and 22 weeks at the prenatal care clinic). The rationale to include this group is that 50-70% of preterm deliveries occur in patients without risk factors for preterm birth.

Consent to participate in the study.

Patient should be able to attend to the Perinatal Research Center for prenatal care and participation in this study.

EXCLUSION CRITERIA:

Preterm labor, preterm PROM, preeclampsia or impaired fetal growth at the time of recruitment.

Any maternal of fetal condition that requires termination of pregnancy.

Known major fetal anomaly or fetal demise.

Active vaginal bleeding.

Multifetal pregnancy with greater than or equal to 3 fetuses.

Serious medical illness (renal insufficiency, congestive heart disease, chronic respiratory insufficiency, etc.).

Severe chronic hypertension (requiring medication).

Asthma requiring systemic steroids.

Patient requiring anti-platelet or non-steroidal anti-inflammatory drugs.

Active hepatitis.

Lack of consent.