Prostaglandin F2 alpha metabolite levels in plasma, amniotic fluid, and urine during pregnancy and labor.

Levels of 13, 14-dihydro 15-keto-prostaglandin F2alpha (dhk PGF2alpha) in the plasma of 30 patients as well as in the amniotic fluid of 17 patients, and 5alpha,7alpha-dihydroxy 11-keto tetranor-prostane 1,16-dioic acid (the main urinary metabolite of PGF2alpha [PGF2alpha MUM]) levels in the urine of 30 patients were measured by radioimmunoassay during pregnancy, labor, and the puerperium. During pregnancy, no increase in dhk PGF2alpha (ng/ml) in plasma was detected as the time of delivery approached. The levels of dhk PGF2alpha during the second stage (0.64 +/- 0.15) and also at delivery (0.88 +/- 0.27) were significantly elevated over those in the first stage (0.38 +/- 0.29) (P less than 0.025 and P less than 0.005, respectively). Its level 2 hours after delivery was reduced to predelivery levels. Its levels in umbilical arterial and venous blood were 0.71 +/- 0.26 and 0.67 +/- 0.26, respectively. A significant elevation (P less than 0.01) of dhk PGF2alpha from 0.89 +/- 0.21 before labor to 6.16 +/- 2.40 at delivery was found in amniotic fluid. The hourly excretion of PGF2alpha MUM (microgram/hour) increased significantly from pregnancy levels to 1.06 +/- 0.45 in the first stage (P less than 0.01), to 7.67 +/- 4.31 (P less than 0.005) for the first 2 hours after delivery, and 2.37 +/- 1.08 from 2 to 12 hours after delivery (P less than 0.01). The excretion of PGF2alpha MUM decreased to pregnancy levels 12 hours post partum. These data indicate that during labor the production of PGF2alpha is remarkably increased.