RETRACTED: Nifedipine alone or combined with sildenafil citrate for management of threatened preterm labour: a randomised trial (Publication with Expression of Concern. See vol. 127, pg. 914, 2020) (Retracted article. See vol. 128, pg. 144, 2021)

Objective To study the tocolytic action of nifedipine combined with sildenafil citrate (SC) and if the combination is superior to nifedipine alone in inhibiting threatened preterm labour (PTL). Design Prospective randomised study. Setting An Egyptian university hospital. Population Women with threatened PTL who received either nifedipine with SC or nifedipine alone. Methods Patients were randomly allocated to receive either (1) nifedipine 20 mg orally (stat dose), followed by 10 mg orally every 6-8 hours at the same time as vaginal administration of SC (25 mg at 8-hourly intervals) or (2) nifedipine alone. Medications were continued for 48-72 hours. Main outcome measures The percentage of women who remained undelivered during hospitalisation. Results From January 2015 to November 2016, 239 women were randomised. The baseline characteristics of participants were similar. Nifedipine combined with SC was associated with more women remaining undelivered (81.8 versus 68.6%; P = 0.018) during hospitalisation. Regarding secondary outcomes, the addition of SC was also associated with fewer deliveries within 7 days of admission (9.1 versus 20.3%; P = 0.014), prolonged latency (29 versus 7 days; P = 0.002), fewer admissions to neonatal intensive care units (31.4 versus 44.1%; P = 0.043), fewer very preterm deliveries (from 28 to <32 weeks, 20.7 versus 38.1%; P = 0.043), and increased neonatal birthweight (1900 versus 1500 g; P = 0.018). Conclusions Vaginal SC combined with nifedipine is an effective option for tocolytic therapy during threatened PTL. Tweetable abstract Vaginal SC enhances the tocolytic effect of nifedipine.