Please select the eligibility criteria that correspond to the clinical trial below.
Title: Ritodrine in Oral Maintenance of Tocolysis After Active Preterm Labor: Randomized Controlled Trial
Brief Summary: This is a trial comparing the efficacy of oral ritodrine in the form of sustained release capsules for the maintenance of uterine quiescence after successfully treated episode of threatened preterm labor.


Options:
A: Inclusion Criteria:

* We will include pregnant women between 22 0/7 to 31 6/7 weeks gestation who present with regular uterine contractions defined as at least one contraction every 10 minutes for 30 minutes with at least one of the following:
* cervical change of at least 1 cm or
* cervical dilation of 2 cm at the time of initial exam or
* positive fetal fibronectin and transvaginal cervical length \<2.5 cm

Exclusion Criteria:

* We will exclude pregnant women with any contraindication to tocolysis:
* clinical chorioamnionitis (defined as a temperature of \>100.4 F and any of the following: fundal tenderness, maternal tachycardia, fetal tachycardia or purulent vaginal discharge)
* non reassuring fetal heart tones
* suspected placental abruption
* preterm premature rupture of membranes
* prior tocolytic treatment during the past 48 hours
* known adverse effect to indomethacin or nifedipine
* already receiving nifedipine for chronic hypertension
B: Inclusion Criteria:

* Pregnancy between completed 24 to 24 weeks
* Successfully treated episode of threatened preterm labour by intravenous preparations
* No uterine contractions

Exclusion Criteria:

* Uterine contractions (painful, clinically palpable, or present on cardiotocography)
* Cervical dilatation of ≥5 cm
* Clinical and laboratory signs of infection defined as offensive vaginal discharge on clinical examination, vaginal pH ≥5, white blood cell (WBC) count \>16×109/L, and C-reactive protein (CRP) \>10 mg/L
* Positive findings of microorganisms rather than normal vaginal flora on high vaginal swab
* Any signs of fetal distress according to cardiotocography, Doppler assessment of blood flow in umbilical artery, and biophysical profile of \<8.
C: Inclusion Criteria:

* . Gestational age between 24-37weeks

  * Symptoms such as low backache , cramping ,pelvic pressure, excessive vaginal discharge and vaginal spotting .
  * Regular uterine contractions at least of 30 seconds duration at a rate of more than 4/30 minutes
  * Cervical changes dilatation less than 3cm,effacement lessthan50%.
  * Intact membranes.

Exclusion criteria

* Active vaginal bleeding and placental abruption.
* Chorioamnionitis and intrauterine infection
* Fetal conditions : fetal death or distress, lethal congenital or chromosomal abnormalities and intra uterine growth restriction
* Maternal conditions indicate that pregnancy shouldn't be continued: eclampsia , severe preeclampsia and cardiac diseases
* Drug specific contraindications(contraindication of tocolysis)
D: Inclusion Criteria:

* Patients between 240/7-320/7 weeks gestation with findings consistent with preterm labor defined by at least one of the following criteria in accordance with regular uterine contractions (\>4 uterine contractions in 20 minutes):

  1. Cervix \> 2 cm in dilation or 80% effaced
  2. Positive fetal fibronectin (if performed).
  3. Demonstrated cervical change between two exams within 90 minutes.

Exclusion Criteria:

* Negative fetal fibronectin
* \> 5cm dilatation
* Multiple gestations
* Known fetal anomalies or chromosomal abnormalities
* Ruptured membranes
* Significant vaginal bleeding
* Suspected chorioamnionitis
* Preeclampsia or uncontrolled hypertension
* Non-reassuring fetal heart tracing
* Placenta previa and/or accreta
* Placenta abruption
* Intrauterine growth restriction
* Maternal renal disease
* Underlying maternal cardiac condition
* Symptomatic hyperthyroidism
* Significant maternal disease
* Contraindication to nifedipine or magnesium
* Cerclage presence
* Tocolytic use within the last 12 hours
* Hypotension (defined as average blood pressure of \<70/40's unresponsive to 1000 cc fluid bolus

Answer: B