Body dimensions of infants exposed to antiepileptic drugs in utero:: Observations spanning 25 years

Purpose: To investigate the influence of maternal antiepileptic drug (AED) treatment on pregnancy duration, birth weight, body length, head circumference, and intrauterine growth in infants exposed in utero to antiepileptic drugs in Sweden between 1973-1997, with 963 singleton infants. Methods: Data collected from (a) 1973-1981 (record linkage between a hospital discharge register and a medical birth register); (b) 1984-1995 (prospectively collected information in one defined catchment area with two delivery hospitals); and (c) 1995-1997 (medical birth register data). Observed numbers of infants below a defined size for body measurements compared with expected numbers calculated from all births in Sweden after stratification for year of birth, maternal age, parity, and education or smoking habits in early pregnancy. Standard deviation scores estimated with same stratification procedures. Results: Fraction of monotherapy exposures increased from similar to 40% to similar to 90% from 1973 to 1997. Significantly increased numbers of infants with small body measurements found in exposed group. Negative influence on body dimensions decreased over time. More marked effects found in infants exposed to polytherapy. In monotherapy, only infants exposed to carbamazepine consistently showed reduction in body dimensions. Significant effect on gestational age in girls and on number of small for gestational age (<2 SD) in boys. Conclusions: Polytherapy with antiepileptic drugs and negative influence on body dimensions decreased. In monotherapy, only carbamazepine has a negative influence on body dimensions in this study.