Reduction of thromboxane A2 synthesis in pregnancy by polyunsaturated fatty acid supplements

High-dose supplements of fish oil reduce thromboxane synthesis in nonpregnant human subjects and were therefore proposed as a means of preventing various small-vessel disorders, including preeclampsia. The effect of fish oil on thromboxane metabolism in pregnancy was investigated in our study.

Sixteen normal pregnant women in the third trimester of pregnancy were treated with a daily ingestion of 6 gm fish oil capsules containing 1.6 gm of n-3 fatty acid. In five patients the treatment was stopped because of severe-flavored reflux and hiccups. Eleven patients completed 3 weeks of treatment. Twenty-four-hour urinary 11-dehydro-thromboxane B2 was measured by means of radioimmunoassay before and after completion of the study protocol in these 11 patients and in seven control pregnant women who did not receive the oil treatment.

A decrease ranging from 32% to 71%, in 24-hour urinary 11-dehydro-thromboxane B2 excretion (mean reduction from 1606 pg/mg creatinine to 779 pg/mg creatinine, p < 0.001) was found among the 11 fish oil-treated women. No change in excretion was found among the control women. No maternal, fetal, or neonatal bleeding disturbances occurred, and no laboratory changes in coagulation markers were observed.

High-dose n-3 fatty acid intake in pregnancy significantly reduces maternal thromboxane A2 synthesis. These results may provide a basis for a possible role of fish oil in managing patients at risk for preeclampsia.