TABLE 3

Log Δ9-THC Concentration by Characteristics of Maternal Cannabis Use and Sample Collection, n = 34 Samples

Estimate95% CIP
Hoursa since last use−0.03(−0.04 to −0.01).005
Uses per db0.51(0.03 to 0.99).039
 Hours−0.02(−0.04 to 0.00).032
Routec
 Hours−0.02(−0.04 to −0.01).008
 Route: other only−0.69(−3.06 to 1.67).553
 Route: both−1.11(−2.64 to 0.41).146
Puffsd−0.04(−0.34 to 0.26).785
 Hours−0.02(−0.04 to 0.00).031
Heavy usee1.13(−0.28 to 2.53).110
 Hours−0.02(−0.04 to 0.00).062
Sample age, mof0.08(0.00 to 0.15).038
 Hours−0.02(−0.04 to 0.00).044
Time of sample collection (pm)g0.27(−0.97 to 1.51).662
 Hours−0.02(−0.04 to −0.01).008
Time since last feed or pump, hh−0.05(−0.18 to 0.09).470
 Hours−0.03(−0.04 to −0.01).005
Feeding frequency, feeds per di0.15(−0.04 to 0.34).117
 Hours−0.02(−0.04 to 0.00).019
  • Separate multivariable linear regression models were used for each covariate with log-transformed ∆9-THC as the outcome. All models include hours since last use as a predictor.

  • a Hours were defined as the number of h between the most recent exposure end date and the date of sample collection.

  • b Uses per d were defined as the average number of uses of marijuana during the most recent exposure period.

  • c Route was defined as categorical variable with the following 3 levels: inhalation, other, and both, with inhalation as the reference category. Inhalation only was defined as a dose unit of joints, puffs, or grams. Other only was defined as a dose unit of drops, milligrams, or servings. Both was defined as a dose unit from both the inhalation only and the other only groups.

  • d For the covariate puffs, the data set was restricted to samples in which the dose unit was indicated as “puffs” (n = 27). The covariate puffs were reported as the number of puffs taken per use of marijuana.

  • e For the covariate heavy use, the data set was restricted to samples in which the dose unit was indicated as puffs (n = 27). The covariate puffs were reported as the number of puffs taken per use of marijuana. Heavy use was defined as women who reported uses per d and puffs greater than the median values in the sample (1 use per d and 3 puffs per use, respectively).

  • f Sample age was defined as the length of time between the date of milk collection and the date the sample was analyzed, measured in mo.

  • g Time of collection was defined as the time of d at which the sample was expressed, measured in number of h after midnight and dichotomized into before noon (am) and after noon (pm).

  • h Time since last feed or pump was defined as the difference between the time of the sample collection and the time of the most recent feed or pump, measured in h.

  • i Feeding frequency was defined as the number of feedings per 24 h.