Different problems can happen at different stages of pregnancy.
It depends on whether a woman drank or took drugs early or late in her pregnancy. Unfortunately, no one knows for sure when the most harm can happen. It depends on when, how much, and how often she drinks or takes drugs. But one thing is for sure: It doesn’t matter if she drinks, smokes, swallows, snorts, or injects them. All drugs (including alcohol, prescription drugs, and cigarettes) sooner or later reach her bloodstream. Then they pass from the mother into the unborn baby’s bloodstream. So even small amounts of alcohol and other drugs can reach the unborn baby. And because the unborn baby is still developing, any alcohol or drugs the woman uses will have more of an effect on the unborn baby’s small system that it does on the mother’s.

Information about the effects of alcohol and drugs on pregnancy can be confusing.  
Many pregnant women will have family and friends who might have used alcohol or other drugs during another pregnancy. And those children seem perfectly healthy. Or the woman feels confused by all the different information she hears. She’s right – information about alcohol and other drug use during pregnancy can be confusing. But this is for sure: using alcohol and other drugs during pregnancy can cause babies to have learning, behaviour, or health problems as they grow up.

It’s never too late to quit or cut down.  Be encouraging.
Support her attempts to try to quit or cut down as soon as possible. She can improve her health and the health of her baby, even if she used to drink or use drugs heavily. But even if she can’t quit using alcohol or drugs completely, don’t give up or get discouraged. When she’s pregnant, anything you do that supports any of the difficult and stressful situations in her life makes a difference.

What helps the mother helps her baby. So if your program, for example, provides nourishing food, then that will mean both the mother and the unborn baby are cared for in a better way. And that means both of them will be healthier, even if the woman is unable to quit using alcohol and drugs. Even a small change can make a big difference.
Want more information about the effects of alcohol and drugs on pregnancy? Check this out:

Give Take: A booklet for pregnant women about alcohol and other drugs