OBJECTIVE: To estimate the performance of combining cervical length measurement with fetal fibronectin testing in predicting delivery in women with symptoms of preterm labor.
METHODS: We conducted a prospective nationwide cohort study in all 10 perinatal centers in The Netherlands. Women with symptoms of preterm labor between 24 and 34 weeks of gestation with intact membranes were included. In all women, qualitative fibronectin testing (0.050-microgram/mL cutoff) and cervical length measurement were performed. Logistic regression was used to predict spontaneous preterm delivery within 7 days after testing. A risk less than 5%, corresponding to the risk for women with a cervical length of at least 25 mm, was considered as low risk.
RESULTS: Between December 2009 and August 2012, 714 women were enrolled. Fibronectin results and cervical length were available for 665 women, of whom 80 (12%) delivered within 7 days. Women with a cervical length of at least 30 mm or with a cervical length between 15 and 30 mm with a negative fibronectin result were at low risk (less than 5%) of spontaneous delivery within 7 days. Fibronectin testing in case of a cervical length between 15 and 30 mm additionally classified 103 women (15% of the cohort) as low risk and 36 women (5% of the cohort) as high risk.
CONCLUSION: Cervical length measurement, combined with fetal fibronectin testing in case of a cervical length between 15 and 30 mm, improves identification of women with a low risk to deliver spontaneously within 7 days.
LEVEL OF EVIDENCE: II
A combination of cervical length measurement and fetal fibronectin testing in threatened preterm labor improves identification of women who will not deliver within 7 days.
Departments of Obstetrics and Gynecology, Academic Medical Center and VU University Medical Center, Amsterdam, University Medical Center Utrecht, Utrecht, Maastricht University Medical Center, Maastricht, Máxima Medical Center, Veldhoven, Erasmus Medical Center, Rotterdam, Isala Clinics, Zwolle, University Medical Center Groningen, Groningen, Leiden University Medical Center, and Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands, Northwestern University Medical School, Chicago, Illinois, and The Robinson Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, Australia; Clinical Epidemiology, Biostatistics and Bioinformatics and the Clinical Research Unit, Academic Medical Center, Amsterdam, and the Department of Clinical Chemistry and Haematology, University Medical Center Utrecht, Utrecht, The Netherlands.
Corresponding author: Gert-Jan van Baaren, MD, Department of Obstetrics and Gynecology, Academic Medical Centre, 1105 DE, Amsterdam, The Netherlands; e-mail: firstname.lastname@example.org.
This investigator-initiated study was funded by The Netherlands Organization for Health Research and Development (ZonMw, grant number 80-82310-98-09056).
Presented at the 33rd Annual Meeting of the Society of Maternal Fetal Medicine, February 11–16, 2013, San Francisco, California.
Financial Disclosure The authors did not report any potential conflicts of interest.