Omega-3 Supplementation Decreases Inflammation and Fetal Obesity in Pregnancy

Inclusion Criteria: * BMI (wt/ht2) \> or = 25 at first antenatal visit * Gestational age at randomization between 8-16 weeks * No medical problems such as hyperlipidemia, hypertension, or pregestational diabetes * Between the ages of 18 and 40 years old * Non-smokers * No obstetrical problems such as a history of preeclampsia or gestational diabetes * Confirmed singleton pregnancy Exclusion Criteria: * Major fetal anomaly * Regular intake of fish oil supplements (defined as greater than 500 mg per week within the last four weeks). This is due to the placebo group receiving fish oil outside of the study. * Daily use of nonsteroidal anti-inflammatory agents * Allergy to fish or fish products, gluten intolerant (because the placebo contains wheat germ oil, which is not gluten free). * Women who are vegetarians and do not eat any fish. * Infants born preterm (less than 36 weeks gestation) or less than 2kg. * Heparin use or known thrombophilia (thrombophilias include homozygous for Factor V Leiden). * Moderate or high titer IgG anticardiolipin antibodies or prolonged activated PTT or other indication of presence of lupus anticoagulant, homozygous for prothrombin gene (G20210A) mutation, antithrombin III deficiency. * Protein S (low levels outside of pregnancy) or Protein C deficiency. * Hyperhomocysteinemia (due to safety concerns because n-3 may affect bleeding time). * Hemophiliacs including von Willebrand's disease (because of safety concerns associated with the hemophilia treatment combined with the n-3 supplements). * Planned termination of pregnancy. * Current hypertension or current use of antihypertensive medication (including diuretics), due to increased risk of adverse pregnancy outcome. * Pregestational diabetes due to increased risks of affecting fetal growth. We will not exclude women who develop GDM during pregnancy but consider a sub-analyses of these women depending on the number of subjects. Known maternal medical complications: cancer (including melanoma but excluding other skin cancers). * Current hyperthyroidism if not adequately controlled. * Renal disease with altered renal function (serum creatinine \> 1.5). * Epilepsy or other seizure disorder. * Systemic lupus (not discoid lupus), scleroderma, polymyalgia rheumatic. * Active liver disease (acute hepatitis, chronic active hepatitis, persistently abnormal liver enzymes). * Platelet or red blood cell disorder (including idiopathic thrombocytopenia purpura, a history of alloimmune thrombocytopenia in a previous offspring, significant anemia due to hemoglobinopathy but not sickle cell trait. Iron deficiency anemia will NOT be an exclusion as long as the hemoglobin is \> 8 gm/dl). * Chronic pulmonary disease (asthma of any degree of severity is NOT an exclusion). * Structural, functional or ischemic heart disease. Neither mitral valve prolapse nor paroxysmal supraventricular tachycardia are considered exclusions. * Known HIV positive with viral load greater than 1,000 copies/ml or CD4 count less than 350/mm3. * Current or planned cerclage due to interference with the natural cause of delivery. * Illicit drug or alcohol abuse during current pregnancy. * At the time of birth, all infants will be evaluated by a pediatrician to make sure that they are healthy. Infants will be excluded from further study if they have any medical problems such as respiratory distress syndrome. * Infants will also be excluded if they have any problems that exclude them from having estimation of body composition, for e.g. birth weight less than 2 kg.