Randomized controlled trial of transcranial magnetic stimulation in pregnant women with major depressive disorder

Major depressive disorder (MDD) affects 10% of pregnancies. Because transcranial magnetic stimulation (TMS) is a nonmedication option, psychiatric patients who do not tolerate or prefer to avoid antidepressants are good candidates for TMS.

In a randomized controlled trial of twenty-two women with MDD in the second or third trimester of pregnancy, subjects were randomized to active TMS (n=11) or sham TMS (n=11). This study took place at a single academic center. Subjects received 20 sessions of TMS to the right dorsolateral prefrontal cortex at 1 Hz as a single train of 900 pulses per session at 100% motor threshold. Estradiol and progesterone and were measured before session 1 and after session 20.

Results demonstrated significantly decreased Hamilton Depression Rating Scale (HDRS-17) scores for the active compared to the sham group (p=0.003). Response rates were 81.82% for the active and 45.45% for the sham coil (p=0.088). Remission rates were 27.27% for the active 18.18% for the sham coil (p=0.613). Late preterm birth (PTB) occurred in three women receiving active TMS. All other maternal and delivery outcomes were normal.

Right-sided, low frequency TMS was effective in reducing depressive symptoms in this sample of pregnant women. There may be a possibility that TMS is associated with late PTB although a larger sample size would be needed for adequate power to detect a true difference between groups. This study demonstrated that TMS is low risk during pregnancy although larger trials would provide more information about the efficacy and safety of TMS in this population. This trial shows that an RCT of a biologic intervention in pregnant women with psychiatric illness can be conducted.