Evaluation of additive effect of quantitative fetal fibronectin to cervical length for prediction of spontaneous preterm birth among asymptomatic low-risk women.
BACKGROUND
Our objective was to evaluate the possible additive effect of quantitative fetal fibronectin to transvaginal ultrasound cervical length measurement between 18(0/7) and 23(6/7)  weeks for prediction of spontaneous preterm birth at <37(0/7)  weeks among asymptomatic low-risk women.


METHODS
A prospective observational study was performed of asymptomatic women with singleton gestations between 18(0/7) and 23(6/7)  weeks and no prior spontaneous preterm birth. Women with multiple gestations, rupture of membranes, vaginal bleeding, intercourse or vaginal exam within 48 h of enrollment were excluded. Physicians were blinded to the quantitative fetal fibronectin levels, but the cervical length measurements were made available. The primary outcome was spontaneous preterm birth at <37(0/7)  weeks.


RESULTS
Of the 528 asymptomatic low-risk women who were prospectively enrolled, 36 (6.82%) had spontaneous preterm birth at <37(0/7)  weeks. Using the receiver-operating characteristic curve, fetal fibronectin value of ≥5 ng/mL was identified as the optimal cut-off for predicting spontaneous preterm birth at <37(0/7)  weeks. As compared with cervical length ≥20 mm alone, with the use of cervical length ≤20 mm or quantitative fetal fibronectin ≥5 ng/mL as screening criteria for prediction of spontaneous preterm birth at <37(0/7)  weeks; sensitivity improved from 11.11 to 61.11%, specificity decreased from 99.59 to 55.08%, positive predictive value decreased from 66.67 to 9.05%, negative predictive value marginally improved from 93.87 to 95.09% and predictive accuracy decreased from 93.56 to 55.49%.


CONCLUSIONS
Although the sensitivity improved, other predictive statistics and predictive accuracy did not improve by the addition of mid-trimester quantitative fetal fibronectin to cervical length measurement. Therefore, addition of mid-trimester quantitative fetal fibronectin to cervical length measurement cannot be recommended at this time for prediction of spontaneous preterm birth at <37(0/7)  weeks in asymptomatic low-risk women.
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Obstetrix Medical Group, Seattle, WA, USA.
Sushma
S
Jwala
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
Tino L
TL
Tran
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
Courtney
C
Terenna
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
Ali
A
McGregor
Division of Biostatistics, Department of Pharmacology and Experimental Therapeutics, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
Jocelyn
J
Andrel
Division of Biostatistics, Department of Pharmacology and Experimental Therapeutics, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
Benjamin E
BE
Leiby
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
Jason K
JK
Baxter
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
Vincenzo
http://orcid.org/0000-0003-2854-0239
V
Berghella
D000328:Adult; D058070:Asymptomatic Diseases; D015415:Biomarkers / Q000378:metabolism; D054791:Cervical Length Measurement; D005260:Female; D005353:Fibronectins / Q000378:metabolism*; D005500:Follow-Up Studies; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D047928:Premature Birth / Q000175:diagnosis* / Q000378:metabolism; D011379:Prognosis; D011446:Prospective Studies; D012372:ROC Curve; D012306:Risk; D012680:Sensitivity and Specificity; D016037:Single-Blind Method
D015415:Biomarkers; C403421:FFN protein, human; D005353:Fibronectins
Asymptomatic; low-risk women; quantitative fetal fibronectin; spontaneous preterm birth; transvaginal ultrasound cervical length