A few cups of yogurt is not going to give you enough probiotics for a healthy immune system. My childbirth and prenatal yoga students tell me they feel so much better after taking these probiotics. YOu need at least 20 billion active cultures. since pregnancy can be a stress on your immune system, you need all the help you can get to have a strong immune system. I’ve been told they help with alleviating heartburn and constipation during pregnancy.