Is induction of labor a risk factor for postpartum hemorrhage (PPH)?

From the Guidelines

Induction of labor is not a significant risk factor for hemorrhage, as the evidence suggests that spontaneous delivery in women receiving therapeutic low molecular weight heparin (LMWH) might be associated with an increased risk of postpartum hemorrhage, not induction of labor. The available data from the 2018 study 1 indicates that women with spontaneous onset of labor had a 1.9-fold increase in the risk of postpartum hemorrhage compared to those who had planned induction of labor. Key points to consider include:

• The risk of major hemorrhage within 24 hours of delivery was 1.2% in pregnant women receiving therapeutic anticoagulation for treatment of venous thromboembolism 1.
• Postpartum hemorrhage occurred in 21 (29.6%) of 71 women receiving LMWH who had a vaginal delivery compared to 50 (17.6%) of 284 control women not receiving anticoagulants 1.
• There was no difference in the risk of postpartum hemorrhage after vaginal delivery in women whose last dose of therapeutic LMWH was less than 24 hours previously compared to those with a ≥24-hour time interval 1. However, it is essential to note that the use of prostaglandin E2 for induction of labor or oxytocin for augmentation of the second and third stages has not been associated with worsening lung function or asthma exacerbation 1. In terms of management, healthcare providers should be prepared for the possibility of postpartum hemorrhage by having uterotonics readily available, including additional oxytocin, methylergonovine, carboprost, or misoprostol. The physiological explanation involves receptor desensitization, where prolonged exposure to oxytocin during induction can reduce the uterus's responsiveness to the hormone after delivery, making it harder for the uterus to contract effectively to prevent bleeding. Overall, the decision to induce labor should be made based on obstetric indications, and modification of the birth plan in women with significant airways disease may be required to ensure specialist staff are available and to minimize the risk of complications 1.

From the FDA Drug Label

Misoprostol can induce or augment uterine contractions A major adverse effect of the obstetrical use of misoprostol is uterine tachysystole which may progress to uterine tetany with marked impairment of uteroplacental blood flow, uterine rupture (requiring surgical repair, hysterectomy, and/or salpingo-oophorectomy), or amniotic fluid embolism and lead to adverse fetal heart changes Maternal shock, maternal death, fetal bradycardia, and fetal death have also been reported with the use of misoprostol The use of misoprostol for the management of postpartum hemorrhage has been associated with reports of high fevers (greater than 40 degrees Celsius or 104 degrees Fahrenheit), accompanied by autonomic and central nervous system effects, such as tachycardia, disorientation, agitation, and convulsions. Overdosage with oxytocin injection (synthetic) depends essentially on uterine hyperactivity whether or not due to hypersensitivity to this agent Hyperstimulation with strong (hypertonic) or prolonged (tetanic) contractions, or a resting tone of 15 to 20 mm H2O or more between contractions can lead to tumultuous labor, uterine rupture, cervical and vaginal lacerations, postpartum hemorrhage, uteroplacental hypoperfusion and variable deceleration of fetal heart, fetal hypoxia, hypercapnia or death Maternal deaths due to hypertensive episodes, subarachnoid hemorrhage, rupture of the uterus and fetal deaths due to various causes have been reported associated with the use of parenteral oxytocic drugs for induction of labor and for augmentation in the first and second stages of labor

Induction of labor is a risk factor for hemorrhage, as it can cause uterine hyperactivity, uterine rupture, and postpartum hemorrhage. Key points to consider include:

• Uterine tachysystole and tetany can lead to marked impairment of uteroplacental blood flow and adverse fetal heart changes.
• Maternal shock, maternal death, fetal bradycardia, and fetal death have been reported with the use of misoprostol and oxytocin for induction of labor.
• Hyperstimulation of the uterus can lead to tumultuous labor, cervical and vaginal lacerations, and uteroplacental hypoperfusion.
• The use of misoprostol and oxytocin for induction of labor requires careful monitoring and management to minimize the risk of complications 2, 3, 3.

From the Research

Induction of Labor and Hemorrhage Risk

• Induction of labor is a common procedure that may be associated with a higher risk of postpartum hemorrhage (PPH) 4.
• A study found that labor induction was associated with a significantly higher risk of PPH, with an adjusted odds ratio of 1.22 4.
• The excess risk of PPH was found for induction with both oxytocin and prostaglandins, with adjusted odds ratios of 1.52 and 1.21, respectively 4.
• Another study discussed the use of misoprostol for induction of labor, which may be associated with an increased risk of uterine hyperstimulation and fetal heart rate changes 5.

Methods of Induction and Hemorrhage Risk

• The method of induction may also play a role in the risk of PPH, with oxytocin and prostaglandins being commonly used methods 4.
• Misoprostol, a synthetic prostaglandin E1 analog, has been used off-label for labor induction and may be associated with an increased risk of uterine hyperstimulation and fetal heart rate changes 5, 6.
• The route of administration of misoprostol, whether vaginal or oral, may also affect the risk of PPH 5.

Guidelines and Recommendations

• Various medical societies have published guidelines on induction of labor, including recommendations on clinical indications and methods 7.
• The guidelines may differ in their recommendations on contraindications, timing, and methods of induction, highlighting the need for an international consensus 7.
• The World Health Organization's guidelines seem to be the most evidence-based, with recommendations based mainly on Cochrane reviews 7.