Correspondence

High Cervical Fetal-Fibronectin Concentrations and Birth within 3 Days in Pregnancies of 41 Weeks or More

N Engl J Med 1995; 332:1105April 20, 1995

Article

To the Editor:

Preterm birth has been reported to occur shortly after the appearance of substantial amounts of fetal fibronectin in vaginal and cervical secretions.1,2 Fetal fibronectin, a component of the extracellular matrix of fetal membranes, leaks into the cervix when the interaction between the fetal membranes and the uterine wall weakens. However, if the vaginal fetal-fibronectin concentration remains low at 39 weeks of gestation, then the pregnancy is likely to progress beyond 41 weeks,3 with an increased risk of perinatal morbidity and mortality.4 If the approximate day of parturition could be predicted, it would aid in deciding whether to induce labor, thereby averting unnecessary interventions.

After obtaining informed consent, we measured the fetal-fibronectin concentrations in cervical secretions from 35 women at 41 weeks' gestation or more (287 to 304 days). All the women had intact membranes, and none were in labor. Specimens were obtained at intervals of three to five days. The fetal-fibronectin concentrations in 58 samples were determined by means of a quantitative immunoassay (Adeza Biomedical, Sunnyvale, Calif.).

Twenty-one women delivered spontaneously, and in 14 women labor was induced. The reasons for induction of labor were a post-term pregnancy of at least 301 days (in eight women), a reduced volume of amniotic fluid (in two), cardiotocographic abnormalities (in one), and psychosocial indications (in three). All the newborn infants were healthy.

In 4 of the 21 women who delivered spontaneously, specimens were not obtained during the last three days before parturition. Sixteen of the 17 women with fetal-fibronectin concentrations of at least 500 ng per milliliter delivered within three days. The sensitivity was 94 percent (95 percent confidence interval, 71 to 100), the specificity was 100 percent (95 percent confidence interval, 72 to 100), and the positive predictive value (delivery in three or fewer days) was 100 percent (95 percent confidence interval, 79 to 100). Eleven samples obtained four or more days before birth had fetal-fibronectin concentrations under 500 ng per milliliter (negative predictive value, 92 percent; 95 percent confidence interval, 74 to 100).

Five of the 14 women with induced labor had fetal-fibronectin concentrations of at least 500 ng per milliliter on the day preceding delivery, whereas 9 had concentrations under 500 ng per milliliter. More than three days before spontaneous or induced parturition, all samples (n = 27) had fetal-fibronectin concentrations under 500 ng per milliliter. We assume that the five women with high fetal-fibronectin values might have gone on to deliver spontaneously if labor had not been induced.

Lockwood et al.3 found that pregnancies continued if vaginal fetal-fibronectin levels remained low. In general, our results show that in pregnancies of 41 weeks or more, birth will usually not take place if cervical fetal-fibronectin values are low. Furthermore, spontaneous delivery will usually take place within three days if the values are at least 500 ng per milliliter. Thus, both low and high values for cervical fetal fibronectin may aid in making the decision to induce labor or wait for spontaneous delivery.

Ronald J.C. Mouw, M.D.
Johannes Egberts, D.V.M., Ph.D.
Jos J.M. van Roosmalen, M.D., Ph.D.
Leiden University Medical Center, 2300 RC, Leiden, the Netherlands

Harry Kragt, M.D., Ph.D.
Diaconessen Hospital, 2275 CX, Voorburg, the Netherlands

4 References

1. 1

   Lockwood CJ, Senyei AE, Dische MR, et al. Fetal fibronectin in cervical and vaginal secretions as a predictor of preterm delivery. N Engl J Med 1991;325:669-674
   Full Text | Web of Science | Medline

2. 2

   Morrison JC, Allbert JR, McLaughlin BN, Whitworth NS, Roberts WE, Martin RW. Oncofetal fibronectin in patients with false labor as a predictor of preterm delivery. Am J Obstet Gynecol 1993;168:538-542
   Web of Science | Medline

3. 3

   Lockwood CJ, Moscarelli RD, Wein R, Lynch L, Lapinski RH, Ghidini A. Low concentrations of vaginal fetal fibronectin as a predictor of deliveries occurring after 41 weeks. Am J Obstet Gynecol 1994;171:1-4
   Web of Science | Medline

4. 4

   Rosen MG, Dickinson JC. Management of post-term pregnancy. N Engl J Med 1992;326:1628-1629
   Full Text | Web of Science | Medline

Citing Articles (2)

Citing Articles

1. 1

   Jane E. Mijovic, Nestor Demianczuk, David M. Olson, Tamas Zakar. (2000) Prostaglandin endoperoxide H synthase mRNA expression in the fetal membranes correlates with fetal fibronectin concentration in the cervico-vaginal fluids at term: evidence of enzyme induction before the onset of labour. BJOG: An International Journal of Obstetrics and Gynaecology 107:2, 267-273
   CrossRef

2. 2

   Regine Ahner, Petra Kub-Csizi, Harald Heinzl, Diana Bikas, Michaela Rabl, Peter Wagenbichler, Peter Husslein. (1997) The fast-reacting fetal fibronectin test: A screening method for better prediction of the time of delivery. American Journal of Obstetrics and Gynecology 177:6, 1478-1482
   CrossRef