A study recently published in the Orphanet Journal of Rare Diseases suggests that thymectomy before delivery strongly correlates with clinical improvement in the postpartum period for pregnant patients with myasthenia gravis (MG).

Myasthenia gravis often affects women of childbearing age, and Su and colleagues aimed to determine the clinical factors linked to outcomes in MG pregnancies. They did a meta-analysis by searching PubMed and EMBASE for cohort and case-control studies reporting MG status during or after pregnancy and related clinical variables.

Across 15 eligible articles, the researchers identified 734 pregnancies with 193 worsening and 51 improved MG episodes. The total worsening proportion was 0.36, with 0.23 during pregnancy and 0.11 after pregnancy. 

The authors evaluated for multiple elements, such as thymectomy before and during pregnancy, steroid use before pregnancy, preterm delivery, parity history, ocular MG, delivery with forceps, complete remission before pregnancy, Cesarean section, anticholinesterase treatments before pregnancy, and acetylcholine receptor (AChR) antibody positivity. None of these elements were associated with MG worsening. 

The total proportion of MG pregnancy improvements was 0.28, with 0.07 during pregnancy and 0.14 after pregnancy. From all the evaluated elements, only thymectomy before delivery was a strong predictor of MG improvement in the postpartum period (odds ratio, 4.85; 95% CI, 1.88-12.50; P =.001). 

Read more about MG prognosis

“As one of the mainstays in the treatments of myasthenia gravis, thymectomy has been accepted as a beneficial and effective treatment that is recommended for all patients concurrence with thymoma or refractory generalized MG with positive AChR antibodies,” the authors stated. “For MG patients who are preparing or undergoing pregnancy, one of the most critical clinical decisions is the timing, safety and benefits of thymectomy. It has been reported that the incidence of neonatal MG was much lower if the mother had thymectomy before delivery (P =.03)”

Although publication bias and heterogeneity of the studies were recognized in this analysis, the authors concluded that “Thymectomy before delivery did not significantly [decrease] the risk of worsening but was found to improve the prognosis. For the better management of MG around pregnancy, thymectomy can be recommended to pursue a better short-term prognosis.”

Reference

Su M, Liu X, Wang L, et al. Risk factors for pregnancy-related clinical outcome in myasthenia gravis: a systemic review and meta-analysisOrphanet J Rare Dis. 2022;17(1):52. doi:10.1186/s13023-022-02205-z