Glossary

opiate – a drug that comes from the opium poppy. Opiates include heroin, codeine and morphine.

trimester – a 12 week period of a pregnancy. Different periods during pregnancy are commonly referred to as the first, second and third trimester.

side effect – an unwanted effect from taking a medicine. Sometimes called an adverse event or drug toxicity.

AIDS – acquired immune deficiency syndrome.

publication bias – the tendency for published results to be different to other trials. For example, trials that show a positive effect are more likely to be reported and published than trials that find no effect.