Here's a link from the Kellymom website: http://www.kellymom.com/health/lifestyle/alcohol.html
Specifically, the article says:
1.) Many experts recommend against drinking more than 1-2 drinks per *week*. (Your question was asking about drinking 1-2 drinks a day...)
2.) Always keep in mind the baby's age when considering the effect of alcohol. A newborn has a very immature liver, so minute amounts of alcohol would be more of a burden. Up until around 3 months of age, infants detoxify alcohol at around half the rate of an adult. An older baby or toddler can metabolize the alcohol more quickly.
3.) One study showed changes in the infant's sleep-wake patterning after short-term exposure to small amounts of alcohol in breastmilk -- infants whose mothers were light drinkers slept less;
Daily consumption of alcohol has been shown in the research to increase the risk for slow weight gain in the infant.
Daily consumption of alcohol (1+ drinks daily) has been associated with a decrease in gross motor development.