Inclusion Criteria:

• * Pregnant as defined by positive test for elevated ß-HCG and having a live, appropriate sized embryo by ultrasound, but \<8 weeks gestation;
• * Antiphospholipid syndrome (APS);
• * Positive for LAC on two or more occasions greater than 12 weeks apart within the previous 18 months. If a candidate for the study is newly diagnosed (\<12 weeks) with APS, meets clinical criteria for APS and has one positive LAC confirmed by review of the medical record, she may be consented and screened. At baseline, LAC will be measured at the study core lab and she will be enrolled if it is found to be positive. The LAC measurement will be repeated 12 weeks after the initial determination and, if positive, she will remain in the study.
• * Age 18-40 (+364 days) years of age and able to give informed consent
• * Laboratory hematocrit \>26% at time of screening.
• the diagnosis of APS and LAC will be confirmed by one of the Co-PI's for each case by a review of the medical records.

Exclusion Criteria:

• * Hypertension (BP \>140/90) present at screening;
• * Multifetal gestation;
• * Type 1 or Type 2 diabetes antedating pregnancy;
• * SLE patients requiring prednisone \>10 mg/day;
• * Platelet count \<100,000 per microliter;
• * Women currently taking prednisone greater than 10 mg daily for an autoimmune disorder, other than immune thrombocytopenia;
• a. More than 60 mg once daily in a tapering regimen or 20 mg once daily in a maintenance regimen for immune thrombocytopenia
• * Women with urinary excretion with greater than 500 mg (0.5 g) per day (spot urine protein/creatinine ration 0.5);
• * Serum creatinine \>1.2 mg/dL
• * History of tuberculosis or untreated positive PPD;
• * Women with a tuberculin skin test induration of 5 mm or greater; or positive quantiFERON-gold test
• * Women with HIV, Hepatitis B or Hepatitis C positive status;
• * Known contraindications or relative contraindications to certolizumab:
• 1. Active infection, e.g., chronic hepatitis B
• 2. History of recurrent infection, e.g., recurrent cellulitis, or opportunistic infection
• 3. History of prior active/treated endemic mycoses in the last two years (including coccidioidomycosis, blastomycosis, or histoplasmosis)
• 4. History of heart failure
• 5. History of peripheral demyelinating disease or Guillian-Barre syndrome
• 6. History of hematologic malignancy
• 7. Prior adverse reaction to certolizumab or o ther anti-TNF-α agent