Nitric oxide levels in women with missed and threatened abortion: results of a pilot study.

The aim of this study was to evaluate the systemic production of nitric oxide (NO) in missed and threatened abortion and in nonpregnant and regular pregnant controls with the purpose of defining its role in the mechanisms regulating the first-trimester pregnancy toward either positive or negative evolution. Patients with missed abortion showed serum NO levels clearly decreased compared with nonpregnant patients and patients with regular pregnancy and threatened abortion, supporting a direct functional role of the NO mediator in early embryonic development and confirming its importance in the uterus and cervix during abortion.