Each mother was administered a structured interview (Drinking and Drug Use During Pregnancy) at the time her child was entered into the follow up study. The interview covered her alcohol, cigarette, and other drug use during each of her pregnancies so that the quantity and frequency of these substances could be determined. The interview format was developed in our laboratory and was designed to measure typical and maximal daily use by obtaining information for each of several substances, noting the quantity per occasion and the frequency of use. Daily use was multiplied by the number of days in each trimester and accumulated for all three trimesters, allowing for the total amount used throughout pregnancy to be calculated. Because drug use involved varying quantities taken by various routes (smoking, intravenous, and inhalation), no attempt was made to analyze these data using quantity estimates. Rather, the number of days any drug was used was calculated and used in the analyses. If the mother had multiple children, she was queried concerning each child separately.
