One unit per day may be relatively safe but many women prefer to abstain from alcohol during pregnancy. It is dangerous to binge drink, drinking 1 unit each day is safer. Drinking excessive amounts of alcohol is most dangerous during the first 11 weeks of pregnancy and can cause congenital malformations. Foetal alcohol syndrome is a syndrome of facial abnormality, small stature, low birthweight, low intelligence and psychological over-activity. This syndrome is seen in children born to mothers who drink excessively.
Alcohol can also be very harmful if consumed shortly before labour.
If you are trying to become pregnant you should consume alcohol within these guidelines and avoid binge drinking.