Reduction of beta-endorphin levels in the amniotic fluid of heroin addicts.

Plasma levels of beta-endorphin and beta-lipotropin in 18 heroin addicts were found to be similar to those in pregnant control subjects at all stages of gestation. In contrast, amniotic fluid levels of beta-endorphin were significantly lower in heroin abusers than in controls in both the first and second trimesters. Amniotic fluid levels of beta-lipotropin were reduced only in the second trimester. At term, when the patients were almost drug free, the amniotic fluid levels of both peptides were in the control range. These data support the existence of a specific control mechanism for amniotic fluid levels of beta-endorphin and beta-lipotropin, independent of the maternal pituitary, and show that exogenous opiates interfere with it negatively.