This study aims to assess the analgesic effect of two different doses of epidural morphine for postpartum analgesia management. Previous studies have shown that conventional management of postpartum pain (acetaminophen, NSAIDs) is insufficient, in the investigators country is wasted using the epidural catheter is placed as part of the analgesic management of pregnant women in labor.

The intervention is the epidural administration of morphine in two doses 2mg and 3mg different vs placebo 1 hour after delivery care maternal vaginal in patients who received epidural analgesia in labor, in order to evaluate the analgesic effectiveness post operations of the different doses vs placebo.

In the analysis to determine whether the proposed levels are effective for postpartum pain control was carried out by determining the differences between experimental groups and control group, and in examining the statistical significance of the differences found by applying the relevant tests according to whether the variable is normally distributed or not.

The main variables analyzed were:

rating of pain intensity, number of analgesics required required dose of analgesics used to achieve adequate control pain, number of pain episodes and percentage of patients free of these episodes, duration of action of the dose used.

Similar analysis was determined by the incidence of side effects, in particular those described in classic form, pruritus, nausea and vomiting, urinary retention, and respiratory depression

Were classified into three groups: two experimental and one control group.

Experimental Group 1 will receive 10 ml of solution prepared as follows:

2 mg of morphine diluted in 0.9% normal saline

Experimental Group 2 will receive 10 ml of solution prepared as follows:

3 mg of morphine diluted in 0.9% normal saline

The control group will receive 10 ml of normal saline (SSN).

The randomization codes were kept in a sealed envelope so individual, and the envelopes were guarded and uncovered after a eligible to participate in the study agreed to be included and signed the informed consent.

Anesthesia Technique for the Study

In ASA II patients in labor who were initiates of labor analgesia with epidural catheter has been placed ideally at the level of L3-L4 (Tuohy catheter conventional number 18, introduced by loss of resistance technique) .

The patients were started a conventional dose of analgesia with bupivacaine 0.5% + fentanyl 100mcg 10mg 10cc carried in a bolus. Administered bupivacaine + 10 mg bolus of fentanyl 100mcg as needed to strengthen the epidural analgesia

or Infusion Bupivacaine 0.125% + Fentanyl 100mcg%

In a 10cc bolus then 8-16CC hours

In patients 1 hour after having her expulsive morphine were previously applied in laboratory and packaged in disregard of the anesthesiologist applied morphine 2mg - 3mg or saline placebo.

The dose will be applied 1 hour after birth in search of having no residual analgesic effect of local anesthetic and opioid epidural analgesia initially applied.

All patients will be managed with conventional analgesia performed in the institution acetaminophen 1 g every 6 hours VO

If additional merit the first choice analgesic diclofenac 75mg IM is, if no answer will apply a dose of 100mg tramadol or morphine IV in titrated only if warranted more analgesia.

For all patients will have availability of naloxone in case of respiratory depression.

Patients will be observed for 24 hours with monitoring the consumption of other analgesics, pain visual analog scale, which is evaluated at the time of the application of morphine, 2h, 4h, 6h 12h and 24h after application of morphine. Also evaluated variables such as development of pruritus, nausea, vomiting, urinary retention and assessment of respiratory rate.

Inclusion Criteria:

• Patients postpartum vaginal conventional analgesia management of your labor
• ASA II
• Do not include patients with history of allergy to morphine.
• Patients who agreed to be included in the study but did not sign informed consent.

Exclusion Criteria:

• Submit a complication that makes it difficult postoperative pain assessment or adverse effects after surgery.
• Patients who, after having been included, express their desire to be excluded. Patients with incomplete follow-up.id
• Did not include patients who have absolute contraindications for epidural anesthesia, or could not provide informed consent, as in the following cases: local infection at the site of administration, systemic infection, bleeding disorders, disease of the spine , mental patients, drug history, sleep apnea, history of headache post-puncture headache or frequent any kind.