Similar to the authors’ present results, Motazedian et al reported that a 48-hour prolongation of pregnancy was achieved in 87% patients receiving terbutaline and 84% patients receiving salbutamol.10 Likewise, the study at Siriraj Hospital, Bangkok, Thailand, revealed that the success rate in threatened preterm labor inhibition for 12 hours with nifedipine was about 80%.11 However, in cases of women with advanced cervical dilatation (4–8 cm) who received one or more tocolytics (magnesium sulfate, indomethacin, or nifedipine), only 23% could prolong pregnancy at least 48 hours after admission.12 Similarly, in cases of women with the diagnosis of preterm labor based on the presence of uterine contraction with documented cervical change, success rate by nifedipine was 70%.13 In these two studies with the lower success rates, the patients presented as preterm labor with apparent cervical changes.