The pattern of drinking alcohol during pregnancy is a very important factor in determining whether the offspring is likely to suffer from neuropsychological and behavioral dysfunction with or without the physical characteristics. There are two major groups of drinking patterns during pregnancy—women who drink continuously during pregnancy and women who binge drink periodically. In the latter instance, many of these women decrease drinking once they find out they are pregnant and then binge occasionally in the second and third trimesters. A binge is defined as drinking at least 5 drinks over a several hour period.
Chronic drinking throughout the pregnancy can produce a variety of effects, including both the physical dysmorphologies and neuropsychological/behavioral dysfunction. The high blood alcohol peaks that occur with binge drinking are also dangerous as they can lead to physical dysmorphologies and neuropsychological/behavioral problems if the binging occurs early in the pregnancy. If binging occurs later in pregnancy , the high blood alcohol peaks can lead to neuropsychological/behavioral problems. In fact, the peak level of blood alcohol reached in the mother during a single binge may be more important than the overall amount of alcohol consumed over a longer period of time! In major studies of mothers who drank during pregnancy, very specific problems have been identified with respect to the pattern of drinking and exposure time. For example, these studies reveal that mothers who drink more than 5 drinks on any day before realizing they are pregnant can expect that their children will be 1-3 months behind their peers in reading and math at the end of 1st grade. Drinking 1 drink/day during the 2nd trimester can lead to problems in academic achievement (reading, spelling, and arithmetic). Moreover, when mothers drink even 1 drink/day, their children may have reduced IQ scores as much as 7 points. Regardless of whether intelligence is reduced, these children can still exhibit many of the behavioral and neuropsychological deficits (discussed in the next section).