Nitric oxide metabolites in preterm and induced labor.
BACKGROUND
Nitric oxide has potent relaxant effects on the pregnant uterus and has been associated with a quiescent uterus in animal and human studies. Nitric oxide donors have been used to arrest preterm labor and a reduction in nitric oxide production has been reported before the onset of labor.


OBJECTIVE
The aim of the study was to estimate the serum levels of nitrate and nitrite in women undergoing spontaneous preterm labor and induced labor.


METHODS
Venous blood was drawn from 39 patients before the onset of labor (control) and also from 17 patients undergoing induction of labor who were in active labor (study group A), and 24 patients in spontaneous preterm labor (study group B). Serum concentrations of nitrate and nitrite were estimated in the samples using the HPLC method.


RESULTS
The maternal age of the patients was similar in all the groups. There was no significant difference in the mean gestational age at delivery between the control and group-A patients (38.86 vs. 38.29 weeks); however, there was a significant difference between the control and group-B patients (38.86 vs. 30.92; p < 0.0001), and between study groups A and B (38.29 vs. 30.92 weeks; p < 0.0001). The mean serum levels of nitrite in groups A and B (0.563 +/- 0.15 and 0.512 +/- 0.13, respectively) were significantly lower than the level in the control group (0.915 +/- 0.13; p < 0.0001). Although the serum nitrate levels in study groups A and B were lower than in the control group, this difference was not significant. The maternal outcome was satisfactory but, as expected, the mean birth weight of the babies in group B (1,665.73 +/- 863.84 g) was significantly lower than the birth weights in the control and group-A patients (p < 0.0001).


CONCLUSIONS
There is a drop in nitric oxide production in active preterm labor and induced labor. These findings need to be confirmed in larger studies to establish the role of nitric oxide in the initiation of labor.
Department of Obstetrics and Gynaecology, Faculty of Medicine, Kuwait University, Safat, Kuwait. michaeldiejo@hotmail.com
Michael F E
MF
Diejomaoh
Alexander E
AE
Omu
Sami
S
Taher
Nasser
N
Al-Busiri
Tunde
T
Fatinikun
Sanjit
S
Fernandes
Saed
S
Al-Othman
D001724:Birth Weight; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005865:Gestational Age; D006801:Humans; D007751:Labor, Induced; D009566:Nitrates / Q000097:blood; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000097:blood; D007752:Obstetric Labor, Premature / Q000097:blood*; D011247:Pregnancy; D011256:Pregnancy Outcome
D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide