Background/Purpose: During pregnancy, women with fibromyalgia (FM) often experience worsening of symptoms, which include widespread pain, fatigue, sleep disturbances, cognitive difficulties, and reduced daily functioning. Although the safety and efficacy of milnacipran in FM patients has been demonstrated in large clinical trials, these studies excluded pregnant women and milnacipran safety in this population is largely unknown. Milnacipran is a serotonin and norepinephrine reuptake inhibitor approved in the US for the management of FM. As with other drugs in this class, milnacipran is currently designated by the FDA as a Pregnancy Category C drug. As FM disproportionally affects women and, as a result, there is potential for exposure to milnacipran in women of child-bearing age, a pregnancy registry was established in October 2009. 

Methods: This ongoing, voluntary, prospective, observational, US-based registry employs an exposure-registration cohort design that allows for the evaluation of birth defects and other pregnancy outcomes in women ≥18 years exposed to milnacipran at any time during pregnancy. Women are followed throughout pregnancy, with their infants followed until 1 year of age. Enrollment in the Registry is initiated by the woman or by her healthcare provider. Pregnancies with evidence of birth defects prior to enrollment are considered retrospective and excluded from the primary analysis to minimize selection bias. All data are reviewed at least yearly by the Registry’s Scientific Advisory Committee. 

Results: To date, 2 prospective subjects have enrolled in the Registry. Both gave birth to premature infants (at 32 and 35 weeks of gestation, respectively). No birth defects have been reported at this time. Enrollment is considerably lower than projected, and is far from the goal of 350 exposed pregnancies and 196 live births. Postmarketing surveillance data from 01Nov11 to 31Oct12 indicate that milnacipran was primarily prescribed to women (88.7%); however, only 21.5% of these women were 18-40 years of age (ie, women with the highest childbearing potential). Healthcare utilization data suggest that the pregnancy rate in women prescribed milnacipran may be <0.5% per year, well below the estimated general population rate of 7%. Other reasons for low enrollment may include pregnancy avoidance due to FM symptoms, the Category C classification, or lack of interest in participating in a voluntary registry. 

Conclusion: Possibly due to the demographics of the target population, enrollment in the Registry has been challenging. The sample size is insufficient to reach conclusions about milnacipran safety in pregnancy. However, the Registry will continue to monitor milnacipran-exposed pregnancies for teratogenicity signals or other negative pregnancy outcomes. Increasing awareness of the Registry among pregnant women who have taken milnacipran and healthcare providers remains a major focus.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/fibromyalgia-and-pregnancy-challenges-of-the-savella-milnacipran-pregnancy-registry/