Can I walk for 30 minutes wen I am pregnant. I want to start living healthy but im scared that change of dieting and strolling might be stressful 4 d baby?

Yes. Of course check with your physician first. But in general 30 minutes of walking a day in most cases woud be beneficial. If you have not been walking , you might need to start slow, gradually building up to your goal of 30 minutes.
Healthy moms R best. Your physician can guide you with any basic limitations to you for a healthy lifestyle while pregnant. I have had moms run their jazercise classes up to days prior to delivery and return to teaching a week later. While this may not be your situation, it shows a pregnant woman can have a vigerous routein and still do well.I applaud you for your efforts. Good luck.
Yes. It is good to exercise when pregnant unless you have been directed not to by your ob/gyn doctor. One should eat a healthy, balanced diet while pregnant.