Effect of maternal anticonvulsant treatment on neonatal blood coagulation.
OBJECTIVE
To investigate the impact of maternal anticonvulsant use on the ability of cord blood to coagulate.


METHODS
Cord blood prothrombin times were measured, over 15 years in a consecutive series of 137 term babies born to women taking phenobarbitone, phenytoin, and/or carbamazepine while pregnant. The response to parenteral vitamin K was measured in 83 neonates.


RESULTS
Only 14 of the 105 babies born to the mothers who had therapeutic anticonvulsant blood concentrations at birth had a prolonged prothrombin time (outside the 95% reference range). None had an overt bleeding tendency. The abnormality was corrected within 2 hours by 1 mg of parenteral vitamin K, but rapid intravenous prophylaxis produced complications in three infants.


CONCLUSIONS
A policy of giving vitamin K throughout the last third of pregnancy to all women being treated with anticonvulsants, as recently recommended, is not justified by the available evidence. The belief that there is a distinct, early form of neonatal vitamin K deficiency that is different from, and more dangerous than, the classic form of the disease, is not supported by a review of the published evidence.
Hey
E
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Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP. shey@easynet.co.uk
D000927:Anticonvulsants / Q000009:adverse effects*; D001777:Blood Coagulation / Q000187:drug effects*; D005260:Female; D005312:Fetal Blood; D006801:Humans; D007020:Hypoprothrombinemias / Q000209:etiology; D007231:Infant, Newborn; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000188:drug therapy; D011297:Prenatal Exposure Delayed Effects; D011517:Prothrombin Time; D014813:Vitamin K Deficiency / Q000097:blood*
D000927:Anticonvulsants