Discussion
death, PTB, Antenatal corticosteroids
RESPIRATORY DISTRESS SYNDROME
Our results, in a predominantly Chinese population are consistent with existing literature We show that in women with TPTL; there is a high NPV (100%, 97.3%) with fFN testing allowing the clincian to rule out delivery in the following 2 weeks when using a cut-off of 10ng/ml and < 50ng/ml respectively [Previous qualitative fFN testing with a single threshold of 50 ng/ml limited its widespread clinical use due to the low sensitivity and PPV [Our results have indicated that a cut-off of < 10 ng/ml can be used to rule out PTB. A double blinded study on fFN in some countries may be difficult since fFN testing is already a standard recommendation for suspected PTB [The average length of hopital stay for patients with TPTL in our unit is approximately 2 days, whilst labour ward management is up to 4 days for the use of corticosteroid and tocolytic therapy. Up to USD$3000 could be saved per admission if the woman is stratified as low risk for PTB with fFN testing [Antenatal corticosteroids has been proven to reduce neonatal mortality (9.3 versus 11.9%, RR 0.78, 95% CI 0.70–0.87), perinatal death (13.3 versus 15.6%, RR 0.85, 95% CI 0.77–0.93) and respiratory distress syndrome (10.5 versus 14.8%, RR 0.71, 95% CI 0.65–0.78) [Patients with results that are not in discriminatory zones of < 10 ng/ml or > 200 ng/ml may benefit from combined testing using transvaginal cervical length measrement (TVCL). Some studies have investigated the use of a combined test to identify pregnancies at risk of PTB. With the use of TVCL measurement, the combined test appeared to perform well in patients with singleton pregnancies [fFN testing is useful even in high risk patient groups. A history of PTB is strongly associated with subsequent PTB [fFN testing has shown utility for PTB prediction within 14 days [The strength of our study would be that all women recruited continued to participate in our study, this is likely due to fFN testing being a simple vaginal swab test performed along with other standard investigations and did not require an additional examination. The attending physician and the women themselves were blinded to the result of fFN test; enabling unbiased management of the women. Regarding the outcomes evaluated, all had been defined in the study protocol at the beginning to evaluate the prediction of the test.Our pilot study has some limitations. Firstly, this cohort has a small sample size which impact the NPV in particular as the background risk of PTB is relatively low in Hong Kong. Clinical validation of a larger sample will remain necessary in the future. Nevertheless, we show that in a Chinese-dominant cohort our results were consistent with published literature that mainly includes Caucasian subjects [