The harms of prolonged postpartum magnesium infusion
The harms of prolonging treatment with postpartum magnesium infusion are generally not emphasized in the medical literature. However, side effects that can occur are flushing, nausea, vomiting, and muscle weakness, delayed early ambulation, delayed return to full diet, delayed discontinuation of a bladder catheter, and delayed initiation of breastfeeding.5,15 In one large clinical trial, 1,113 patients with preeclampsia with severe features who received intrapartum magnesium for ≥8 hours were randomized after birth to immediate discontinuation of magnesium or continuation of magnesium for 24 hours.15 There was 1 seizure in the group of 555 patients who received 24 hours of postpartum magnesium and 2 seizures in the group of 558 patients who received no magnesium after birth. In this trial, continuation of magnesium postpartum resulted in delayed initiation of breastfeeding and delayed ambulation.15
Balancing the benefits and harms of postpartum magnesium infusion
An important clinical point is that magnesium treatment will not prevent all seizures associated with preeclampsia; in the Magpie trial, among the 5,055 patients with preeclampsia treated with magnesium there were 40 (0.8%) seizures.5 Magnesium treatment will reduce but not eliminate the risk of seizure. Clinicians should have a plan to treat seizures that occur while a woman is being treated with magnesium.
In the absence of high-quality data to guide the duration of postpartum magnesium therapy it is best to use clinical parameters to balance the benefits and harms of postpartum magnesium treatment.16-18 Patients may want to participate in the decision about the duration of postpartum magnesium treatment after receiving counseling about the benefits and harms.
For patients with preeclampsia without severe features, many clinicians are no longer ordering intrapartum magnesium for prevention of seizures because they believe the risk of seizure in patients without severe disease is very low. Hence, these patients will not receive postpartum magnesium treatment unless they evolve to preeclampsia with severe features or develop a “red flag” warning postpartum (see below).
For patients with preeclampsia without severe features who received intrapartum magnesium, after birth, the magnesium infusion could be stopped immediately or within 12 hours of birth. For patients with preeclampsia without severe features, early termination of the magnesium infusion best balances the benefit of seizure reduction with the harms of delayed early ambulation, return to full diet, discontinuation of the bladder catheter, and initiation of breastfeeding.
For patients with preeclampsia with severe features, 24 hours of magnesium may best balance the benefits and harms of treatment. However, if the patient continues to have “red flag” findings, continued magnesium treatment beyond 24 hours may be warranted.
Red flag findings include: an eclamptic seizure before or after birth, ongoing or recurring severe headaches, visual scotomata, nausea, vomiting, epigastric pain, severe hypertension, oliguria, rising creatinine, or liver transaminases and declining platelet count.
The hypertensive diseases of pregnancy, including preeclampsia often appear suddenly and may evolve rapidly, threatening the health of both mother and fetus. A high level of suspicion that a hypertensive disease might be the cause of vague symptoms such as epigastric discomfort or headache may accelerate early diagnosis. Rapid treatment of severe hypertension with intravenous labetalol and hydralazine, and intrapartum plus postpartum administration of magnesium to prevent placental abruption and eclampsia will optimize patient outcomes. No patient, patient’s family members, or clinician, wants to experience the grief of a preventable maternal, fetal, or newborn death due to hypertension.19 Obstetricians, midwives, labor nurses, obstetrical anesthesiologists and doulas play key roles in preventing maternal, fetal, and newborn morbidity and death from hypertensive diseases of pregnancy. As a team we are the last line of defense protecting the health of our patients. ●