typically does not increase the risk for obstetric complications, and well-controlled disease can remain stable throughout pregnancy (a small subset of women may have a flare in the first trimester or postpartum).

Patients may continue to take acetylcholinesterase inhibitors (eg, pyridostigmine) during pregnancy; additional medications may be discontinued based on teratogenicity and disease control during the preconception period.

en obstetric complications do occur in patients with MG, management is tailored to avoid disease exacerbation (eg, respiratory muscle weakness).  This patient has a commonly seen obstetric complication, preeclampsia with severe features (eg, hypertension, headache, visual changes).  In patients without MG, management of preeclampsia with severe features includes magnesium sulfate for seizure prophylaxis.  However, in patients with MG, magnesium sulfate is contraindicated because it may trigger a myasthenic crisis (eg, oropharyngeal muscle weakness, respiratory failure requiring intubation) due to inhibition of acetylcholine release at the neuromuscular junction.  In these patients, seizure prophylaxis is with valproic acid.

(Choice A)  Acetaminophen is not contraindicated in pregnancy or in patients with MG and can be used to improve this patient's headache.

(Choice B)  Antihypertensive therapy is used in pregnant patients with severe hypertension (ie, systolic blood pressure ≥160 mm Hg or diastolic blood pressure ≥110 mm Hg) to decrease the risk of stroke.  Although some antihypertensives (eg, beta blockers, calcium channel blockers) can exacerbate muscle weakness in patients with MG, hydralazine does not and is not contraindicated in this patient.

(Choice D)  Oxytocin is used for labor augmentation and induction.  Contraindications to oxytocin include prior classical cesarean delivery (due to the risk of uterine rupture) or fetal heart rate decelerations, which are not seen in this patient.  MG is not a contraindication to oxytocin use.

(Choice E)  Intrapartum penicillin is administered to patients with positive rectovaginal screening for group B Streptococcus to decrease the risk of neonatal transmission.  Although some antibiotics (eg, azithromycin, gentamicin) can worsen symptoms of MG, penicillin typically does not and, therefore, is not contraindicated in this patient.