Urinary cGMP levels during pregnancy with and without uterine contractions

The purpose of this study was to investigate the nitric oxide-cGMP (NO-cGMP) system by urinary cGMP level determinations in pregnant women with and without uterine contractions.

cGMP expressed in nmol/mmol of creatinine was performed by radio immuno-assay (Amersham UK) in urine samples obtained from 94 pregnant women with non-complicated pregnancies. Population A without contractions (n = 62) was divided into three groups according to the gestational age (group I, < or = 15 weeks; group II, 16-33 weeks; group III, > 33 weeks). The group III from A population was compared to B population (of the same gestational age) presenting uterine contractions (n = 32).

In A population, no significant urinary cGMP level differences were observed whatever the gestational age. Nevertheless, the comparison between patients with or without uterine contractions (A III and B populations) showed a significant difference by a variance analysis (P < 0.05). Lower levels of cGMP were seen when uterine contractions occurred.

Urinary cGMP levels are significantly decreased in pregnant women with uterine contractions, without any difference from early to late pregnancy. These results, completed by more precise investigations, could suggest that the NO-cGMP system might be implicated in uterine quiescence.