Intravenous (IV) Nitroglycerin for Versions in Nulliparous Women (INVERT (01))

• Success of ECV (ie fetus in cephalic presentation) at time of delivery [ Time Frame: At time of delivery ] [ Designated as safety issue: No ]
• Mode of delivery [ Time Frame: At time of delivery ] [ Designated as safety issue: No ]
• Maternal side effects and adverse events [ Time Frame: During ECV ] [ Designated as safety issue: Yes ]

Breech presentations (where a baby presents with feet or bottom down) have an increased risk of perinatal and neonatal complications, and are usually delivered by cesarean section. As an alternative, so that the baby can be delivered vaginally, an attempt can be made to turn the baby so that it is head down: this manoeuvre is called an external cephalic version (ECV).

Drugs that relax the uterus (tocolytic agents) are sometimes used to help improve ECV success rates. Nitroglycerin is a tocolytic agent, but intravenous nitroglycerin has not been tested as an agent to help ECV. There is some suggestion that nitroglycerin may be more helpful in women who have not previously been pregnant (nulliparous women) than in women who have been pregnant more than once (multiparous women), and so we have planned two trials.

This study is designed to answer the following questions for nulliparous women:

Will administration of IV nitroglycerin for uterine relaxation improve ECV success rates? Will an increase in ECV success result in a decreased cesarean section rate?

• Breech Presentation
• Complication of Pregnancy

• Drug: IV Nitroglycerin
  IV injection, initial dose of 1ml, with further doses of 1-3mL, up to a recommended maximum of 10mL
• Drug: Normal saline
  IV injection, initial dose of 1ml, with further doses of 1-3mL, up to a recommended maximum of 10mL

• Active Comparator: 1
  Treatment solution consisted of 100 micrograms/mL of nitroglycerin. After an initial 1ml dose, further doses could be given in 1-3mL increments until uterine relaxation was achieved, or up to a recommended maximum of 10mL
  Intervention: Drug: IV Nitroglycerin
• Placebo Comparator: 2
  Placebo solution was saline. After an initial 1ml dose, further doses could be given in 1-3mL increments until uterine relaxation was achieved, or up to a recommended maximum of 10mL
  Intervention: Drug: Normal saline

Inclusion Criteria:

• any non-cephalic presentation
• singleton pregnancy
• >/= 37 weeks gestational age
• normal amniotic fluid volume
• reassuring fetal heart rate

Exclusion Criteria:

• labor
• ruptured membranes
• history of third trimester bleeding
• any pre-existing uterine scar
• pregnancy induced hypertension and gestational diabetes
• oligohydramnios and polyhydramnios
• intrauterine growth restriction or macrosomia
• hypotension or any serious medical illness
• inability to comprehend the consent form