This can cause a bias toward the null, diluting an existing risk see more because of inclusion of cases that were not exposed during embryogenesis. However, in August of 2013, Andersen et al9 from Denmark presented a second study using the same Danish registries covering more years (1997-2010) and more pregnant women (897,018 vs 608, 835). In contrast to Pasternak et al,8 Andersen’s study detected a 2-fold increased risk of cardiac malformations with ondansetron (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.3–3.1),

leading to an overall 30% increased risk of major congenital malformations. To rule out confounding by indication, Andersen et al9 also examined metoclopramide taken for morning sickness, detecting no increase in teratogenic risk. The fact that the same large registry can be investigated to yield such opposing results is concerning. There

is an exponential rise in use of prescription database linkage to birth registries. None of these were designed specifically to address fetal drug safety, and there may be flaws in the quality and completeness of the available data. Of potential importance, a recent large case control study by the Sloan epidemiology unit and the Centers of Disease Control and Prevention, has reported a 2-fold increased risk for cleft palate associated with ondansetron taken for NVP Regorafenib in the first trimester of pregnancy

(OR, 2.37; 95% CI, 1.28–4.76).10 The maternal safety of ondansetron has been challenged in June 2012, when the FDA issued a warning of possible serious cardiac output (QT) prolongation and Torsade the Pointe among people receiving ondansetron. 11 As a result, the FDA requires strict workup of patients receiving ondansetron, to rule out long QT, electrolyte imbalance, congestive heart failure or taking concomitant medications that prolong the QT interval. 12 Because this drug is not approved by the FDA for pregnant women, the FDA did not specifically address precautions in pregnancy. However, in the context of NVP, women with severe NVP often exhibit electrolyte abnormalities (hypokalenia or hypomagnesemia). Idoxuridine Presently, counseling of women who receive ondansetron for morning sickness suggests that these FDA precautions are not being followed. Serotonin syndrome is a life-threatening disorder of excessive serotonergic activity, typically occurring when 2 or more serotonin-modifying agents are used simultaneously, although it may also occur with a single agent.12 From Jan. 1, 1998, to Dec. 30, 2002, Health Canada received 53 reports of suspected serotonin syndrome, most often reported with the use of selective serotonin reuptake inhibitors (SSRIs), monoamine oxidase inhibitors and selective serotonin- norepinephrine reuptake inhibitors.