Frequency of Performing Umbilical Artery Doppler in the Third Trimester in High Risk Pregnancy

Inclusion Criteria: * I-Singleton pregnancy. II-In the third trimester (starting from 28 weeks of gestation till the time of delivery), Gestational age will be determined by the date of the last menstrual period and early ultrasound. III-Patient considered as high-risk pregnancies will be included in this study. The following will be considered as high-risk status: 1. Previous obstetric history of preeclampsia or eclampsia, abruptio placenta, intra-uterine growth restriction or still birth. 2. Pre-existing medical disorders like: 1. Pregestational diabetes (Ang et al., 2006) 2. Renal diseases (such as nephrotic syndrome, chronic renal failure, renal transplant and hemodialysis) (Divon and Ferber, 2012). 3. Autoimmune diseases (such as systemic lupus erythromatosis and rheumatoid arthritis) (Divon and Ferber, 2012). 4. Acquired thrombophilias (such as antiphospholipid syndrome). On the other hand, inherited thrombophilias (such as protein C or S deficiency) are not associated with IUGR (Reeves and Galan, 2012). 5. Chronic maternal hypoxemia due to pulmonary disease (such as uncontrolled asthma, chronic obstructive pulmonary disease and cystic fibrosis), cardiac disease (such as cyanotic heart disease) or hematologic disorders (such as severe anemia, sickle cell anemia and β-thalassemia) (Baschat et al., 2012). 3. Current preeclampsia or pregnancy-induced hypertension (PIH). PIH is diagnosed in women whose blood pressure reaches 140/90 mm Hg or greater for the first time after midpregnancy, but proteinuria is not identified. Preeclampsia is best described as pregnancy-specific syndrome that can affect virtually every organ system.It is much more than simply gestational hypertension with proteinuria (Cunningham et al, 2010). IV- Obtaining valid informed consent to participate in the study Exclusion Criteria: * I-Patients with congenital anomaly of the fetus. As this will affect fetal outcome with no effect of Doppler changes. II- Patients with multiple gestations. As they have different growth pattern. III- Patients with unconfirmed Gestational age due to lack of sure reliable date and absent early trimesteric scan. As we cannot diagnose small for gestational age without sure date. IV- Withdrawal of consent.