In the case of drinking alcohol without knowing the pregnancy, the results may be varied, the common cases are as follows: 1, if it is before the formation of the gestational sac, even if the amount of alcohol consumed is relatively large, it will not affect the fetus, the development of the fertilized egg within 7 days of pregnancy is relatively delayed, basically will not have an impact; 2, if it is 1-3 months of pregnancy, this is a critical period for the development of the fetus, but also a critical period for the development of the fetal neural tube If you are pregnant, even a small amount of alcohol is likely to have an adverse effect on the fetus, and alcohol consumption should be strictly prohibited. If you drink alcohol without knowing that you are pregnant, you need to go to the prenatal clinic to do tests, such as non-invasive DNA, amniocentesis, check chromosomes; 3, if you are more than 12 weeks pregnant, within 28 weeks, the development of the fetus has been relatively mature, a small amount of alcohol will not have adverse effects; 4, after 28 weeks of pregnancy, drinking alcohol, the development of the fetus is close to maturity, basically no adverse effects.