Micronized progesterone reduces vasoconstriction in the placenta.

OBJECTIVE

To investigate if micronized progesterone (P4) has the ability to attenuate thromboxane mimetic U46619-mediated fetoplacental artery vasoconstriction.

METHODS

Paired cotyledons obtained from the same placenta of five-term subjects were analyzed. The fetal artery and maternal intervillous space of one cotyledon was infused with P4 while another cotyledon was infused with control perfusate. After 30 min, a bolus dose of U44619 was administered to both cotyledons.

RESULTS

The change in the measured fetoplacental vascular pressure caused by bolus administration of U46619 was less in the cotyledons infused with P4 (p = 0.009).

CONCLUSION

Continuous treatment with P4 significantly attenuates the U46619-mediated fetoplacental vasoconstriction.