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Abstract

We thank Dr Heyborne for his interest in our work. As he says, we did state in our meta-analysis on women with threatened preterm labor (PTL),1Berghella V. Saccone G. Fetal fibronectin testing for prevention of preterm birth in singleton pregnancies with threatened preterm labor: a systematic review and metaanalysis of randomized controlled trials.Am J Obstet Gynecol. 2016; 215 (Society for Maternal-Fetal Medicine Preterm Birth Toolkit. Available at:) (Accessed Feb. 9, 2017): 431-438https://tinyurl.com/hvn2fdzAbstract Full Text Full Text PDF PubMed Scopus (82) Google Scholar that “further study must be undertaken to better understand whether and under what circumstances the predictive characteristics of the fetal fibronectin [FFN] test can be translated into better clinical management.” This is for several reasons, of which we want to highlight at least two. First, as Dr Heyborne states, protocols were not used in all randomized controlled studies (RCTs) included. FFN is predictive of preterm birth (PTB) in women with PTL, but we might not have studied the right interventions for those with positive results. Second, our meta-analysis might have been underpowered to detect an effect. The incidence of spontaneous PTB <37 weeks was 20.7% in the FFN knowledge group and 29.2% in the no FFN knowledge group, with a relative risk of 0.72 (so a 28% decrease in spontaneous PTB), but the 95% confidence intervals just crossed 1 (0.52–1.01).1Berghella V. Saccone G. Fetal fibronectin testing for prevention of preterm birth in singleton pregnancies with threatened preterm labor: a systematic review and metaanalysis of randomized controlled trials.Am J Obstet Gynecol. 2016; 215 (Society for Maternal-Fetal Medicine Preterm Birth Toolkit. Available at:) (Accessed Feb. 9, 2017): 431-438https://tinyurl.com/hvn2fdzAbstract Full Text Full Text PDF PubMed Scopus (82) Google Scholar A bigger sample size, which can be achieved by further and larger RCTs, might certainly make FFN eventually associated with significant benefits. Unfortunately, until further studies are done, in 2017 so far one cannot recommend FFN to be routinely done for women with PTL. That is why neither the Society for Maternal-Fetal Medicine2American College of Obstetricians and GynecologistsManagement of preterm labor. ACOG Practice bulletin no.127.Obstet Gynecol. 2012; 119: 1308-1317Crossref PubMed Google Scholar nor the American College of Obstetricians and Gynecologists3Ness A. Visintine J. Ricci E. Berghella V. Does knowledge of cervical length and fetal fibronectin affect management of women with threatened preterm labor? A randomized trial.Am J Obstet Gynecol. 2007; 197: 426.e1-426.e7Abstract Full Text Full Text PDF Scopus (100) Google Scholar recommend FFN use alone for women with PTL. The use of transvaginal ultrasound (TVU) cervical length (CL) in women with PTL has instead been better supported by evidence from RCTs.4Berghella V. Palacio M. Ness A. Alfirevic Z. Nicolaides K.H. Saccone G. Cervical length screening for prevention of preterm birth in singleton pregnancy with threatened preterm labor: systematic review and meta-analysis of randomized controlled trials using individual patient-level data.Ultrasound Obstet Gynecol. 2017 Mar; 49 (Epub 2017 Feb 8. Review): 322-329https://doi.org/10.1002/uog.17388Crossref PubMed Scopus (85) Google Scholar The best evidence for use of FFN in women with PTL is for those with TVU CL 20–29 mm when a positive FFN can lead to more aggressive management with admission, steroids, and possibly tocolysis, while a negative FFN can lead to a discharge home.4Berghella V. Palacio M. Ness A. Alfirevic Z. Nicolaides K.H. Saccone G. Cervical length screening for prevention of preterm birth in singleton pregnancy with threatened preterm labor: systematic review and meta-analysis of randomized controlled trials using individual patient-level data.Ultrasound Obstet Gynecol. 2017 Mar; 49 (Epub 2017 Feb 8. Review): 322-329https://doi.org/10.1002/uog.17388Crossref PubMed Scopus (85) Google Scholar, 5SMFM PTB Toolkit. Available at: https://www.smfm.org/publications/231-smfm-preterm-birth-toolkit. Accessed April 20, 2017.Google Scholar This is part of a PTL management algorithm based mostly on TVU CL screening, as shown in the Figure and suggested in the Society for Maternal-Fetal Medicine PTB Toolkit, both on the website5SMFM PTB Toolkit. Available at: https://www.smfm.org/publications/231-smfm-preterm-birth-toolkit. Accessed April 20, 2017.Google Scholar and on the app.6SMFM Preterm Birth Toolkit App. Available at: https://appsto.re/us/AYOjeb.i. Accessed on April 20, 2017.Google Scholar In conclusions, we do agree with Dr Heyborne that “the more appropriate conclusion should be that further study of FFN within a strict clinical protocol, possibly in conjunction with cervical sonography, is warranted.”