Please select the eligibility criteria that correspond to the clinical trial below.
Title: Tocolysis for Preterm Labor
Brief Summary: Preterm birth is the most common and costly complication in obstetrics. It complicates up to 11% of all pregnancies and it is responsible for 70% of sick babies. The ideal way to stop preterm labor when it occurs (which drug to use) is not known. Currently magnesium sulfate is used by about 95% of all practitioners, but recent data suggest magnesium given this way may be harmful for the baby's future development. Other drugs such as antiprostaglandin agents are very effective in stopping uterine activity, but particularly when used for \>48 hours have been associated with both maternal and fetal sides effects. Lastly, calcium channel antagonists are effective in stopping contractions and have very little in the way of maternal and fetal side effects, but less data is available in the United States on their use. Because there is no FDA approved drug to stop preterm labor, we purpose to randomize all women with preterm labor (20-34 weeks) to receive one of the above three methods of stopping preterm labor. The primary outcomes will be to see which agent stops the uterine contractions most effectively, for the longest period of time with fewest relapses and results in significant prolongation of pregnancy. If one of these agents is clearly superior to the other two it would help women avoid early delivery or have significant extension of their pregnancy to avoid some of the complications of preterm birth in the baby.


Options:
A: Inclusion Criteria:

• Singleton pregnancy women between 22 and 34 weeks of gestation who presented with threatened preterm labor.

Exclusion Criteria:

* Multiple pregnancies
* Women with Preterm Prelabour Rupture of Membrane
* Fetal death
* Women with bad obstetric history
* Women with history of cervical incompetence
* Contraindication to Nifedipine such as cardiovascular disease, hyperthyroidism, severe pre eclampsia or to Utrogestan
* Maternal or fetal indication for immediate delivery, such as fetal distress, bleeding placenta previa, abruption placenta
* Contraindication for tocolysis, for example severe pre eclampsia, intrauterine growth restriction, fetal anomaly, chorioamnionitis, significant antepartum haemorrhage
* Cervical dilatation of 3cm or more
* Patients with previous tocolytic treatment during this pregnancy
* Women who refuse to participate in this study
B: Inclusion Criteria:

* Singleton pregnancy. A twin pregnancy reduced to singleton (either spontaneously or therapeutically) before 140 weeks by gestational age (see dating below) is acceptable.
* Gestational age at randomization between 240 weeks to 315 weeks by using the dating determinations as below
* Preterm labor with intact membranes. Preterm labor is defined as at least 6 regular uterine contractions in 60 minutes either seen on tocodynamometer, palpated by health providers and/or subjectively felt by the patient and at least one of the following:

  1. Associated with cervical change by cervical dilation greater than or equal to 1cm OR effacement greater than or equal to 25 to 50%
  2. Cervix greater than or equal to 2cm dilated on initial digital exam
  3. At least 75% effaced on initial digital exam
  4. Short cervical length (defined by each institution's policy) as obtained by transvaginal cervical sonography \[in general, this is defined as a measurement of 2.0 - 2.5 cm or less\] and/or a positive fetal fibronectin test (defined as a level greater than 50ng/mL).
* Intact membranes
* 18 years of age or older

Exclusion Criteria:

* Fetal demise, or known major fetal anomaly, including cardiac anomaly and hydrops
* Maternal contraindication to nifedipine: preload cardiac lesions or maternal hypotension (systolic blood pressure less than 100 or diastolic blood pressure less than 60). A delayed dose can be given if blood pressure improves - it will be documented if dose is delayed, how long from scheduled dose it was delayed and reason for delay.
* Maternal contraindication to indomethacin: platelet dysfunction or bleeding disorders, hepatic dysfunction, gastrointestinal ulcerative disease, renal dysfunction and asthma
* Obstetrical contraindication to tocolysis not already mentioned: non reassuring fetal status, severe preeclampsia or eclampsia, maternal bleeding with hemodynamic instability, chorioamnionitis, preterm premature rupture of membranes
* Participation in another interventional study that influences neonatal morbidity or mortality
* Participation in this trial earlier in the pregnancy
* Maternal allergy to either indomethacin or nifedipine
* Maternal allergy to aspirin and other NSAIDs.
* Maternal hypertension requiring treatment.
* Maternal kidney disorder that would require adjustment in magnesium dosing.
C: Inclusion Criteria:

* Pregnancies with intact membranes in confirmed preterm labor;
* 20 - 32 weeks' gestation;
* Cervical dilatation 0 - 3cm versus 4 - 6cm;
* No conditions contraindicating continued pregnancy (severe IUGR, chorioamnionitis, non-reassuring fetal tracing - physician judgement); AND
* Able and willing to consent to the study protocol.

Exclusion Criteria:

* Failure to meet admission criteria;
* Known serious fetal malformations;
* Severe maternal/obstetric disease affecting the mother or fetus (severe cardiac disease, placental abruption/previa, severe diabetes, severe preeclampsia, etc. - physician judgment);
* Allergic to magnesium, antiprostaglandin or calcium channel antagonist;
* Refusal or inability to consent to the study
D: Inclusion Criteria:

* Placenta previa is diagnosed when the lowest placental edge is located within 5 cm of the internal os at ultrasonography
* Placenta previa may be symptomatic with at least one episode of bleeding
* Estimated gestational age within 24 to 34 weeks
* Maternal age \> 18 years
* Informed consent after received an explanation of the study and an information sheet
* Social affiliation

Exclusion Criteria:

* Premature rupture of membranes
* Severe bleeding requiring an immediate termination of pregnancy
* Abnormal fetal heart rates requiring an immediate termination of pregnancy
* Intrauterine fetal death
* Pre-eclampsia, chorioamnionitis, liver disease, severe chronic renal disease, heart disease
* Abruptio placentae
* Nifedipine sensibility
* Drugs interaction with nifedipine

Answer: C