EUROMAC. A European concerted action: maternal alcohol consumption and its relation to the outcome of pregnancy and child development at 18 months. Results--strategy of analysis and analysis of pregnancy outcome.

Analyses were made of the relation between maternal alcohol consumption before and in early pregnancy and five infant outcome variables: birthweight, crown-heel length, occipitofrontal circumference and the Apgar scores at 1 and 5 minutes. The data were analysed for all centres combined and separately. From tabulation of the mean values of the outcome variables by alcohol consumption, it appeared that a poorer outcome was related to consumption of 120 g/week absolute alcohol or more. Multiple regression analysis was used to allow for possible confounding by the child's gestational age at birth and sex, the mother's age, parity and smoking habit, and survey centre. Two threshold models were applied to the combined data, taking the confounders into account. The offset threshold model (assuming no effect of alcohol up to a threshold value, and then a constant multiplicative effect at higher levels) suggested a negative effect on birthweight at about 60 g/week absolute alcohol, but with a wide 85% confidence interval of 5-130 g/week. A step function threshold model, which assumes a constant effect above the threshold value, behaved erratically. Similar analyses for crown-heel length and occipitofrontal circumference provided only a very poor fit to the data. Data on reported congenital anomalies are presented by survey centre and maternal alcohol consumption, but due to the unstandardized method of collection they were not analysed further.