Breastfeeding & Drugs: Marijuana

Marijuana passes into breast milk.

Astley and Little evaluated a group of women who had used marijuana during lactation. They found a decreased score on the Psychomotor Development Index (motor scale) of the Bayley Scales of Infant Development at one year of age associated with marijuana use in the first month of breastfeeding but no correlation with marijuana use during the third month of breastfeeding. Three quarters of these mothers had also used marijuana during pregnancy. The difference in Psychomotor Development Index scores persisted when they controlled for this prenatal marijuana use.

There was no effect of marijuana use on the Mental Development Index scores ( Astley, 1990 ).

Another report evaluated the growth and developmental outcomes of children whose mothers used marijuana during pregnancy and lactation. They found no difference in the mental or motor scores between the two groups ( Tennes, 1985 ).