Nausea during pregnancy and congenital heart defects: A population-based case-control study

The authors investigated the possible association between a mother's nausea during pregnancy and her child's risk for a congenital heart defect using data from the population-based Atlanta Birth Defects Case-Control Study con ducted in 1982-1983. Case infants (n = 998) had nonsyndromic congenital hea rt defects and control infants (n = 3,029) had no congenital defects. Nause a during pregnancy (NP) was graded in eight levels of "severity" based on i ts onset, frequency, and duration. Level 1, the most severe NP, was associa ted with a lower risk for a congenital heart defect in the child (odds rati o (OR) = 0.81, 95% confidence interval (CI) 0.67-0.99) compared with no nau sea. The lower risk tended to disappear with less severe levels of nausea, and the trend was statistically significant. Overall, early NP (levels 1 to 4 combined) with use of antinausea medication, particularly Bendectin(R) ( doxylamine, dicyclomine (dropped from the formulation in 1976), pyridoxine (vitamin B-6)), was associated with a lower risk for congenital heart defec ts compared with: 1) absence of nausea (OR = 0.67, 95% CI 0.50-0.92), and 2 ) nausea without medication use (OR = 0.70, 95% CI 0.50-0.94), The results suggest that pregnancy hormones and factors or, alternatively, a component of Bendectin(R) (most probably pyridoxine) may be important for normal hear t development. These findings outline potential areas for future research o n and prevention of congenital heart defects.