system
Given the following post, respond as if you're commenting on Reddit:
human
What are the Effects of Drinking Alcohol Before Knowing that You're Pregnant?

I have to imagine lots of people drink alcohol before finding out that they are pregnant.  Shouldn't this cause more issues with the baby's development?  Isn't this the critical time for development when it could have the most effect on the baby?
gpt
Here’s some science, and ignore the fear mongering above: in the first 2 weeks after fertilization the product of fertilization is called a zygote and then very soon after, a blastocyst. At this point, excessive alcohol consumption can prevent the blastocyst from implanting in the uterine wall leading to an early (and probably unnoticed) miscarriage.  The cells in the blastocyst are undifferentiated meaning they can potentially become any type of cell line in the eventual embryo, and they are sustained by their own cell nutrients. No maternal circulation has been established at this point, so it’s unlikely that the mother (can we still use this word?) will negatively affect the cell development at this early stage of pregnancy. This is true only in the first 2 weeks of pregnancy. In week three, a process wherein the embryo develops into three differentiated cell layers, each of which will become individual parts of the developing fetus, occurs. At this point alcohol (and other drugs and environmental hazards) can definitely exert a harmful effect on the developing embryo.  So, it’s best to figure out by 2 weeks if you’re pregnant and avoid alcohol after that point.