Pregnancy and SMA

**Pregnancy **

As noted earlier, all SMA types are associated with a restrictive, progressive respiratory insufficiency. Thus, pregnancy in women with SMA is associated with increased risk because of impaired respiratory function, which is further limited in many cases by kyphoscoliosis and wheel chair dependency. In addition, limited retrospective data suggest that pregnancy in women with SMA is often complicated by preterm labor and an increased frequency of urinary tract infections.

Despite these issues, no deleterious effects have been detected with respect to fetal outcome. Successful pregnancies have been reported in women with SMA who have forced vital capacities of 50 to 70 percent of predicted values.

Ideally, such pregnancies should be managed by obstetricians and anesthesiologists familiar with neuromuscular disorders. There are no guidelines regarding mode of delivery. Successful outcomes have been reported with both cesarean section and vaginal delivery. Spinal and epidural anesthesia may be difficult because of severe spine deformity. However, there is no evidence of an increased risk of malignant hyperthermia in SMA.

Women with SMA may experience worsening of muscle weakness after the second trimester and/or delayed postpartum recovery. In one report, an uneventful pregnancy and cesarean section was followed by extreme muscle weakness with dyspnea and bulbar involvement lasting one to two weeks. Motor function then improved to baseline.