IV Acetaminophen vs IV Morphine for Pain Control in Pregnant Women

Rationale for this clinical trial The goal of analgesia in pregnancy is to reduce pain while
minimizing both maternal and fetal adverse effects. Current opioids used in pregnancy provide
minimal pain relief and are associated with adverse effects. IV acetaminophen has been shown
to significantly improve pain control following cesarean section and in the first stage of
labor. Moreover, IV acetaminophen reduces the need and consumption of opioids following
surgery. If IV acetaminophen can be as effective in controlling pain associated with maternal
medical conditions and uterine contractions with labor, then the use of parenteral opiods in
pregnant women and its exposure to the fetus could be reduced. This could provide new
opportunities in the medical management of pain in pregnancy. Thus we propose a comparative
effectiveness trial of IV acetaminophen compared to IV morphine.

Hypothesis:

We hypothesize that IV acetaminophen is as effective as IV morphine in reducing pain in
pregnant women. In doing so, IV acetaminophen can reduce the amount of narcotics needed in
women with pain.

Objectives:

To determine if IV acetaminophen can:

1. Decrease pain in pregnant women

2. Reduce the amount of opioid use in pregnant women who encounter pain

3. Reduce maternal and fetal adverse effects compared to opioids

Study Design:

For this comparative effective trial, we propose a randomized, controlled trial of IV
acetaminophen vs. IV morphine in pregnant women. Prior studies have confirmed that IV
acetaminophen is effective in controlling pain compared to placebo.[14,20] Thus,
administering just a placebo for pain control is not justified at this time.

We will include 3 different groups of pregnant populations who encounter pain for different
reasons.

Group 1: Pregnant women with uterine contractions, but not in labor Group 2: Pregnant women
with uterine contractions in the first stage of labor Group 3: Pregnant women with a medical
condition associated with pain.

Inclusion criteria:

Group 1. We will include pregnant women greater than 24 weeks of pregnancy who present with
uterine contractions, but are not in labor and who are warranting treatment with
intravenous medication for pain control as part of their routine treatment. This will be
defined as the presence of uterine contractions documented on the tocodynanometer. However,
the cervix remains less than 2 cm dilated and has not changed after 1 hour after
re-examining her cervix.[23]

Group 2. We will include pregnant women greater than 34 weeks of pregnancy who present with
uterine contractions and are in the first stage of labor and who are warranting treatment
with intravenous medication for pain control as part of their routine treatment. This will
be defined as the presence of uterine contractions documented on the tocodynanometer and
cervical dilation greater than 2 cm, but less than 6 cm. [23]

Group 3. We will include pregnant women greater than 16 weeks of pregnancy who present with
pain due to a maternal medical condition including sickle cell crisis, pyelonephritis,
pancreatitis, cholecystitis, nephrolithiasis or headache and who are warranting treatment
with intravenous medication for pain control as part of their routine treatment.

Exclusion criteria:

We will exclude women less than 18 years of age, less than 16 weeks gestation, with weight
less than 50 kg, and contraindications to acetaminophen including reported elevated liver
function tests, hepatic injury, hepatic disorder, active liver disease, alcoholism, chronic
malnutrition, known coagulapathy, hemorrhage, creatinine > 1.0, or known allergy or
hypersensitivity to acetaminophen. We will also exclude women who have received any opioids
within the last 24 hours.