Safety of the 2010-11, 2011-12, 2012-13, and 2013-14 seasonal influenza vaccines in pregnancy: Birth defects, spontaneous abortion, preterm delivery, and small for gestational age infants, a study from the cohort arm of VAMPSS.

INTRODUCTION: There is a need for pregnancy safety information overall and for each seasonal formulation of the influenza vaccine. METHODS: As part of the cohort arm of the Vaccines and Medications in Pregnancy Surveillance System, vaccine-exposed and unexposed women in the U.S. or Canada were recruited during pregnancy in the 2010-2014 vaccine seasons and followed to pregnancy outcome. For the four seasons combined, crude and adjusted relative risks (RRs) were estimated with 95% confidence intervals (CIs) for major birth defects overall and infants small for gestational age. Crude and adjusted hazard ratios (HRs) were estimated with 95% CIs for spontaneous abortion and preterm delivery. Specific influenza season subanalyses were also conducted. RESULTS: Of 1730 women, 1263 were exposed to an influenza vaccine and 467 were unexposed to any influenza vaccine. Among pregnancies with first-trimester exposure excluding lost-to-follow-up, 26/457 (5.7%) resulted in an infant with a major birth defect compared to 13/427 (3.0%) in the unexposed (RR 1.87, 95% CI 0.97, 3.59). No specific pattern of defects was evident in the vaccine-exposed cohort. The overall risk of spontaneous abortion was not elevated (HR 1.09, 95% CI 0.49, 2.40). Adjusted HRs for preterm delivery approximated 1.0 (adjusted HR 1.23, 95% CI 0.75, 2.02). RRs for small for gestational age infants on weight, length and head circumference ranged from 1.19 to 1.49 with all CIs including 1. Season-by-season analyses resulted in variation by season; however, estimates were based on small numbers. CONCLUSIONS: Combining the 2010-2014 influenza seasons, we found a moderately elevated RR for major birth defects overall, but no evidence of a specific pattern; 95% CIs included 1, and this finding could be due to chance. In the combined seasons, we found no meaningful evidence of an increased risk for spontaneous abortion or preterm delivery following exposure to the seasonal influenza vaccine.

Birth outcomes in women who have taken leflunomide during pregnancy.

OBJECTIVE: In preclinical reproductive studies, leflunomide was found to be embryotoxic and teratogenic. Women treated with leflunomide are advised to avoid pregnancy; those who become pregnant are advised to reduce fetal exposure through a cholestyramine drug elimination procedure. The present study was undertaken to investigate pregnancy outcomes in women who received leflunomide and were treated with cholestyramine during pregnancy. METHODS: Sixty-four pregnant women with rheumatoid arthritis (RA) who were treated with leflunomide during pregnancy (95.3% of whom received cholestyramine), 108 pregnant women with RA not treated with leflunomide, and 78 healthy pregnant women were enrolled in a prospective cohort study between 1999 and 2009. Information was collected via interview of the mothers, review of medical records, and specialized physical examination of infants. RESULTS: There were no significant differences in the overall rate of major structural defects in the exposed group (3 of 56 live births [5.4%]) relative to either comparison group (each 4.2%)(P = 0.13). The rate was similar to the 3-4% expected in the general population. There was no specific pattern of major or minor anomalies. Infants in both the leflunomide-exposed and non-leflunomide-exposed RA groups were born smaller and earlier relative to infants of healthy mothers; however, after adjustment for confounding factors, there were no significant differences between the leflunomide-exposed and non-leflunomide-exposed RA groups. CONCLUSION: Although the sample size is small, these data do not support the notion that there is a substantial increased risk of adverse pregnancy outcomes due to leflunomide exposure among women who undergo cholestyramine elimination procedure early in pregnancy. These findings can provide some reassurance to women who inadvertently become pregnant while taking leflunomide and undergo the washout procedure.