Woman gives birth to healthy child while on Spinraza treatment
Case may inform future guidelines for pregnancy and SMA, researchers say
A 33-year-old woman with spinal muscular atrophy (SMA) type 3 became pregnant while on Spinraza (nusinersen) treatment, and subsequently gave birth to a healthy child, according to a case report.
The case “helps to elucidate new approaches for future guidelines in the management of pregnancy and SMA,” the researchers wrote in the study, “Successful pregnancy of an SMA type 3 sitter on Nusinersen therapy – a case report,” published in BMC Neurology.
Nearly all SMA cases are caused by mutations in the SMN1 gene, leading to the loss of nerve cells that control muscle movement. This results in progressive muscle weakness and atrophy (wasting), mainly affecting motor function. It can also cause problems with speaking, swallowing, and breathing.
Due to advances in disease-modifying therapies (DMTs), or those that slow disease progression, more SMA patients are reaching childbearing age. “While extensive data on pregnant SMA patients from the pre-treatment era is not available, even less is known with regard to pregnancy and DMT,” the scientists wrote.
The research team at the Ludwig-Maximilians-University of Munich described the case of a 33-year-old woman with SMA type 3 who became pregnant while taking Spinraza.
SMA progression
Early development was normal for the woman. She sat up at six months and walked independently by one year. After reaching all motor milestones by age 2, however, she experienced weakness when climbing stairs.
Her symptoms progressively worsened until age 13, when she could no longer stand or walk and was assigned to a wheelchair. Difficulties raising her arms above her head had been reported for several years.
She began Spinraza treatment at 27. By that time, she had weakness in all four limbs, contractures of both knee joints and Achilles tendons, and areflexia (when muscles don’t respond to stimuli). Her breathing was unaffected.
The woman received Spinraza for three years without any relevant side effects. During treatment, her overall motor function improved, as assessed with the Hammersmith Functional Motor Scale-Expanded (HFMSE), as did her upper limb function, as indicated by the Revised Upper Limb Module (RULM). While her lung function remained stable, her hand grip slightly worsened.
At 30, she became pregnant while receiving Spinraza, which was administered for the last time during the third week of pregnancy. Treatment was paused after 13 doses. In the 25th week of pregnancy, HFMSE scores slightly worsened, but RULM scores remained stable.
Due to HELLP syndrome, a rare pregnancy complication that affects the blood and liver, she gave birth at 34 weeks by cesarean section. “HELLP syndrome was not mentioned as a complication in former studies of SMA patients, and can be seen as a coincidence in this patient,” the scientists noted.
Her newborn daughter appeared normal in size for her gestational age. Her breathing was normal, and she reached all motor milestones over the next two years.
After a short period of breastfeeding, the SMA patient restarted Spinraza treatment. At that time, she reported deterioration in motor function, particularly in the arms, which was confirmed with lower RULM scores but stable HFMSE scores. Again, her breathing remained stable.
Four months after restarting treatment, the RULM scores slightly improved. Although HFMSE and RULM scores stabilized over the next two years of treatment, they remained below pre-pregnancy values. She also reported a gradual decline in upper arm strength with reduced endurance.
“Our case shows that although [Spinraza] treatment was applied in the third gestational week prior to proof of pregnancy, outcome was positive for mother and child,” the scientists wrote. “Future studies will have to determine whether ongoing treatment with [Spinraza] during pregnancy should be recommended.”