SAN FRANCISCO — Women with generalized myasthenia gravis (gMG) who become pregnant face sharply higher risks for preterm birth and cesarean delivery — and much higher healthcare costs — a new analysis of health claims data showed.

Pregnant patients with gMG were 2.5 times more likely to have a preterm birth (P = .021) and 2.64 times more likely to have a cesarean delivery (P = .006) than those without the disease, said study investigator Nolan Campbell, PhD, medical director of Autoantibody Neuroimmunology at Johnson & Johnson, Horsham, Pennsylvania, and colleagues.

“These are obviously outcomes we would hope to avoid, and they speak to the need to improve disease management for these patients with the goal of avoiding such outcomes,” Campbell told Medscape Medical News.

The findings were presented on October 29 at the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) 2025.

Unique Clinical Challenges

Pregnancy in women with gMG presents unique clinical challenges, but data on real-world outcomes remain sparse. The investigators sought to fill this gap, as evidence on how gMG affects maternal and neonatal outcomes, as well as associated healthcare costs, remains limited despite the condition’s higher incidence among women of reproductive age.

“In the modern treatment era for MG in the US, there is still unmet need for this population of women who are pregnant,” said Campbell.

The study included 97 pregnant patients with gMG and 970 pregnant individuals without the disease. Participants, aged 18-49 years, were treated between January 1, 2016, and March 30, 2023, and were identified through the Komodo Research database. The cohorts were weighted by age, race, region, insurance type, and index year to ensure comparability.

Demographic characteristics were similar between groups: The mean age was 32 years, and racial distribution was 37% White, 13.4% Black or African American, 19.6% other, and 28.9% unknown. Participants were geographically distributed across the US, with 38.1% residing in the South, 28.9% in the Northeast, 18.6% in the Midwest, and 14.4% in the West.

Most patients (72.2%) had commercial insurance, followed by Medicare Advantage (19.6%) and Medicaid (8.2%). Preterm birth occurred in 21.1% of those with gMG vs 9.6% of those without, and cesarean delivery rates were 21.1% and 9.9%, respectively.

There were no statistically significant differences between the groups in live birth, abortion (induced or spontaneous), or ectopic pregnancy.

Mean gestational age among those with live births was lower in the gMG cohort (37.0 weeks) than in the non-gMG cohort (38.2 weeks; P = .008).

Researchers found no significant difference in mean pregnancy-related costs per month between the gMG and non-gMG groups ($1016 vs $890; P = .264). However, mean overall healthcare costs were markedly higher among patients with gMG ($5269 vs $2099; P < .001).

Campbell noted that in patients with poorly controlled disease, fatigue and muscle weakness may contribute to the higher rates of preterm birth and cesarean delivery observed in the gMG cohort because these symptoms can complicate carrying a pregnancy to term or completing a vaginal birth.

Experts Weigh in

Commenting on the research for Medscape Medical News, neurologist Kavita M. Grover, MD, of Henry Ford West Bloomfield Hospital in West Bloomfield, Michigan, who was not involved in the study, said that MG itself is not considered an indication for cesarean delivery.

However, she added that obstetricians may be more likely to choose cesarean delivery out of caution, given the potential risks to both mother and infant in the setting of neuromuscular weakness.

She also noted that the causes of both cesarean delivery and preterm birth could be due to more than one cause. Potential factors could include gMG and medications, she said.

Also commenting on the findings, Jenny Linnea Victoria Lindroos, MD, of the University of Bergen, Bergen, Norway, noted that the results are consistent with those of her 2025 nationwide study on pregnancy in women with gMG, which included 134 births from 1999 to 2022 in women with the disease.

In that study, the rate of cesarean delivery was higher among women with MG, largely due to a greater proportion of planned procedures. The odds of elective cesarean delivery were nearly twice as high in the myasthenia cohort as in the control group (adjusted odds ratio [aOR], 1.8).

The investigators also observed elevated risks for neonatal complications, particularly feeding difficulties (aOR, 4.9) and transfer to a neonatal care unit (aOR, 5.1).

“We also found a higher risk for preterm birth — 8% in MG vs 5% in non-MG — although this did not reach statistical significance in our registry-based study,” she said.

Regarding management of gMG in women who may become pregnant, Lindroos recommended performing thymectomy — the surgical removal of the thymus gland — as early as possible in women of childbearing potential. Thymectomy can improve long-term disease control and reduce the need for immunosuppressive therapy, which may carry risks during pregnancy.

For managing pregnancy in women with MG, Grover emphasized the importance of avoiding medications that pose risks to the fetus, noting that safe options exist for treating disease exacerbations.

Patients showing signs of worsening disease can be treated effectively and safely with intravenous immunoglobulin or plasmapheresis, she said, adding that there is no reason to avoid either therapy during pregnancy or in cases of myasthenic crisis.

Lindroos also recommended at least two routine ultrasounds during uncomplicated pregnancies, with serial scans in the third trimester when possible.

She also emphasized the importance of close postnatal observation, advising that all newborns be monitored in hospital for at least 3 days for signs of transient neonatal myasthenia. When both mother and baby are otherwise healthy, she added, this monitoring can be done in a mother- and baby-friendly setting that allows rooming-in and encourages breastfeeding.

The study was funded by Johnson & Johnson, and several authors disclosed having relationships with the company or Analysis Group, which provides consulting services. Grover disclosed having a relationship with Johnson & Johnson. Lindroos disclosed having relationships with UCB, the Norwegian Association for Muscle and Nerve Disorders, and the General Medical Research Fund at the University of Bergen.