Pregnancy oral anticoagulants

Oral anticoagulants should not be used during pregnancy as they can be the cause of birth defects and abortion. 

Oral anticoagulants are ordinarily contraindicated in the presence of active or past gastrointestinal ulceration thrombocytopenia hepatic or renal disease malignant hypertension recent brain, eye, or spinal cord surgery bacterial endocarditis chronic alcoholism and pregnancy. These agents also should not be prescribed for individuals with physically hazardous occupations. 

Meclofenamate and mefenamic acid (Table 36-1) inhibit both COX and phospholipase A2. Meclofenamate appears to have adverse effects similar to those of other NSAIDs, though diarrhea and abdominal pain may be more common it has no advantages over other NSAIDs. This drug enhances the effect of oral anticoagulants. Meclofenamate is contraindicated in pregnancy its efficacy and safety have not been established for young children. 

When chemotherapeutic mercaptopurines are being given concomitantly with allopurinol, their dosage must be reduced by about 75%. Allopurinol may also increase the effect of cyclophosphamide. Allopurinol inhibits the metabolism of probenecid and oral anticoagulants and may increase hepatic iron concentration. Safety in children and during pregnancy has not been established. 

In patients with artificial heart valves, management in pregnancy is problematic, because the efficacy of heparin has not been established. Two approaches have been recommended. One can use heparin in a therapeutic dosage throughout pregnancy or use heparin until the 13th week, followed by an oral anticoagulant until the middle of the third trimester, and then heparin until delivery. 

Other consequences of oral anticoagulation during pregnancy are spontaneous abortion, stillbirth, and premature birth (87). 

Stevenson RE, Bmton OM, Ferlauto GJ, Taylor HA. Hazards of oral anticoagulants during pregnancy. JAMA 1980 243(15) 1549-51. 

Long-term anticoagulation Oral anticoagulation therapy (target INR 2.5 range 2.0-3.0) should be continued for at least 3 months. If oral anticoagulation therapy is contraindicated (e.g., pregnancy), a treatment dose of FMWH or adjusted-dose UFH should be used. 1A... 

Pettifor, J. M. and Benson, R. (1975) Congenital malformations associated with the administration of oral anticoagulants during pregnancy. J. Pediat., 86, 459. 

Any underlying cause should be addressed for example, patients with a definite thrombophilia should probably take anticoagulation drugs for life oral contraceptives should never be used again, but a further pregnancy may be safe (Preter et al. 1996). 

---