Table 1 Characteristic of included studies (Randomized controlled trials)

Richter 2005 [23]

Germany

Prospective-RT

40 (n = 20 vs. n = 20)

Women, 31–42 years of age, between 18 to 24th week of gestation and with uterine contractions duration >30 s, rate ≥ 4/30 min. Cervical effacement >50 % and cervical dilatation of 0–3 cm (nulliparous), and 1–3 cm (primiparous and multiparous)

Atosiban

Placebo

Prolongation of pregnancy >48 h

(Initial intravenous infusion of 6.75 mg of atosiban in 0.9 ml of sodium chloride, and followed by high dosage of infusion (300 lg/ min) for 3 h and then low dosage (100 lg/min) up to 45 h.)

(Intravenous infusion of saline solution)

Prolongation of pregnancy >7 days

Romero 2000 [21]

USA

RCT

501 (n = 250 vs. n = 251)

Women between gestational age of 20 weeks to 33 weeks, with intact membranes, cervical dilatation of 1 to ≤3 cm, preterm labor required the presence of ≥4 uterine contractions over 30 min, each lasting at least 40 s.

Atosiban

Placebo

Prolongation of pregnancy >24 h

77 ^a (n = 43 vs. n = 34)

(Initial intravenous infusion of 6.75 mg of atosiban over 1 min and followed by an infusion of 300 μg/min of atosiban for 3 h, and then 100 μg/min for up to 45 h.)

(Matching placebo contained same formulation minus the 5 % mannitol solution of atosiban.)

Prolongation of pregnancy >48 h

Prolongation of pregnancy >7 days

Perinatal death

The Canadian PLIG 1992 [22]

Canada

RCT

708 (n = 352 vs. n = 356)

Women between gestational age of 20 to 35 weeks, with uterine contractions four per 20 min or six per 60 min or any uterine activity with ether rupture membranes or cervical dilatation by 2 cm or more.

Ritodrine

Placebo

Perinatal death

151 ^a (n = 76 vs. n = 75)

(Intravenous infusion of ritodrine in 5 % dextrose at a rate of 0.35 mg/min until the cessation of uterine activity, the failure of therapy, or occurrence of impermissible maternal side effects

(Dextrose solution alone without ritodrine)