The objective of this study to assess the impact of Myasthenia Gravis (MG) serological status on pregnancy-related and neonatal outcomes.

Pregnancy has a variable effect on the course of MG.  Current knowledge describes an increased likelihood of flares in the first trimester and the postpartum period, an increased risk of caesarean section and ICU admission, transient neonatal MG and arthrogryposis. It's unknown if serological status impacts pregnancy and neonatal outcomes.

An onlinesurvey was developed in conjunction with patient representatives from the MyastheniaGravis Foundation of America. Respondents who have (or had) ovaries, uterus, and/or cervix with a diagnosis of MG. For the current analysis, those with at least one pregnancy in prior 10 years were included. Information on disease course, pregnancy complications, antibody status, fetal and neonatal outcomes was collected.

157 opened the survey, and 142 met entry criteria for a response rate of 90%. 96 pregnancies were analyzed. MG symptoms appeared to worsen regardless of antibody status in the first trimester and postpartum. Antibody negative vs AchRAB and MUSK participants respectively, reported a greater risk of ICU admission (23% vs 16% and 12% , P =0.058 ) intubation ( 50% vs 4% and 17% P value 0.007) C-section ( 92% vs 23% and 42%, put p-0.001), neonatal MG rates (67% vs 8% and 0%,  P value 0.001), and unplanned pregnancy (75% vs 21% and 50% , put p-value 0.004).

This is the first know study of the association between negative serological status and poor pregnancy outcomes and although limited in size, may influence future preconception counselling and pregnancy monitoring. Highlighting the importance of interdisciplinary preconception and antenatal care including Neurology, Maternal-Fetal-Medicine and Neonatology. Findings of transient neonatal myasthenia gravis and arthrogryposis in seronegative individuals suggests that another, currently unknown antibody or biological process may be present in the seronegative group. Future, larger studies are warranted.