Alcohol
Alcohol should be avoided completely throughout pregnancy. There is no known safe level of alcohol during pregnancy.
The NHS advises that the safest approach is not to drink any alcohol during pregnancy. Alcohol passes through the placenta to the baby, and a baby's developing liver cannot process it the way an adult's can. Drinking during pregnancy can cause fetal alcohol spectrum disorders (FASDs), which affect the baby's physical and mental development. There is no established safe level of alcohol consumption at any stage of pregnancy. This applies to all types of alcohol — beer, wine, spirits, cider, and cocktails. Alcohol-free and low-alcohol drinks (under 0.5% ABV) are generally considered safe, but if you are in doubt, check with your midwife or GP.
NHS guidance: https://www.nhs.uk/pregnancy/keeping-well/foods-to-avoid/
US guidance
US guidance from the CDC and the Surgeon General is consistent with NHS advice — no level of alcohol is considered safe during pregnancy. The US Surgeon General advises complete abstinence from alcohol throughout pregnancy.