[Levels of fetal fibronectin in the cervix and vagina during pregnancy]

Fibronectin is a glycoprotein produced by different types of cells. It can be divided into two main groups--soluble fibronectin, found in human plasma and other body fluids (amniotic fluid) and tissue fibronectin, found in basal membrane and connective tissue between endothelial cells (2). There are three subtypes--plasmatic, cellular and onco-fetal fibronectin, the most important during pregnancy, with different concentrations during the course of pregnancy. The aim of the study is to establish normal distribution of fetal fibronectin in cervicovaginal fluid during pregnancy in our population and afterwards establish the relation between concentrations in different stages of pregnancy and the pregnancy outcome.

This prospective, observational study was done at the Department of Obstetrics and Gynaecology, Clinical Centre Novi Sad, during the period June-October 1988. The presented results are preliminary ones. The patients were randomly chosen from the population that came for routine consultations as well as the ones hospitalized at the Department, at the High Risk Pregnancy Unit, for reasons other than threatening miscarriage and preterm delivery. One-hundred and thirty two pregnant women were examined, divided into three groups, according to gestational age. In group I were women between 7-20 weeks, in group II between 21 and 37 weeks and in group III 38 and more weeks. In every case general and obstetric data were collected, and cervico-vaginal fibronectin was taken from the posterior vaginal fornix, using a special kit (Specimen Collection Package, Adeza Biomedical). Fetal fibronectin concentration was tested using enzyme immunoassay (Adeza Biomedical) and positive was considered the concentration of and above 0.05 microgram/ml.

The mean cervico-vaginal fibronectin concentration, uncorrected for the outcome of the pregnancy was as follows--in group I 0.045 (0-0.11) microgram/ml, group II 0.037 (0-1.22) microgram/ml, and in group III 0.226 (0.001-1.05) microgram/ml. The concentration trend was from weakly negative during the period 7-20 weeks, over highly negative (21-37 weeks) to very positive, after 38 weeks. The positive/negative relation in group I was 29.2%/70.8%, group II 11.7%/88.3% and group III 48.4%%/51.6%. After the correction of the results for miscarriages/preterm deliveries/failed induction in postterm pregnancies, the mean concentrations were somewhat different--group I 0.029 microgram/ml, II 0.019 microgram/ml and III 0.282 microgram/ml. The relations of positive and negative results were changed as well and in group I the relation was 27.3%/72.7%, group II 6.8%/93.2% and group III 71.4%/28.6%.

After the correction for duration and outcome of the pregnancy, our results differed from the results in the literature. Thus in the 1st trimester fetal fibronectin was positive in cervico-vaginal fluid of 27.3% pregnant women, which is double the number usually found in the literature, between 21 and 37 weeks, when a positive result (> 0.05 microgram/ml) would be expected in only 3% of cases, it was positive in 6.8%, whereas 2.3 of the women delivered at term had a positive concentration. The discrepancy in group II (21-37 weeks) cannot be explained neither with a higher incidence of late miscarriages, nor preterm deliveries, for the incidence of such complications was only 3%, which is far less than usually found in the non-selected population (10%) (9). It is also possible that the discrepancy in our results and the results found in literature is based on a fact that our population was not preselected, which was the case in other studies' populations that did not include women with heavy, non-treated vaginal discharge, nor the ones that had sexual intercourse within 24 hours from the moment of fibronectin sampling. (ABSTRACT TRUNCATED)