A common question many women ask is during my in vetro fertilization cycle "Can I smoke, can I drink alcohol, can I use certain recreational drugs, can I even have intercourse?" These are all very good questions. There are obviously many very good reason to not smoke and drink for health related issues. From a fertility standpoint we do know that smoking has a very profound effect on egg number and egg quality over the long term. It's even been shown that women who smoke heavily will go into menopause even years earlier than their non smoking counterparts.
There is no evidence that a couple of glasses of wine per week or a couple of mixed drinks per week during the fertility process is going to have an adverse affect on egg quality or on chances of conceiving. Heavy alcohol consumption, however, can very much have an affect on a potentially causing genetic damage in eggs. When that occurs specifically is not completely known. There are no good data suggesting how much alcohol puts you at risk of any egg damage or fertility abnormalities, but fertility doctors will state that it is best to not drink heavily or to smoke at all, or to use any recreational drugs during the fertility process.