The Australian antiepileptic drug in pregnancy register: Aspects of data collection and analysis

Internal comparisons using the data of the Australian Register of Antiepileptic Drugs in Pregnancy as of November 2005, and comparisons with Australian population data, were carried out. It was found that (i) except for under-representation of mothers of Asian origin, the demography of the register population was reasonably representative of the Australian situation; (ii) except for more pregnancies terminated for foetal malformation, malformation rates were similar in retrospectively and non-retrospectively enrolled pregnancies; (iii) some 21% of foetal malformations would have been excluded by not including malformations first recognised after the neonatal period; and (iv) in practice, the comparator against which malformation rates were expressed made little difference to the rates found. It is desirable to have available such analyses of pregnancy register data before comparing the findings of different registers.