My first three months i lost ten pounds and im now 27 weeks and gained it back for the baby it made me feel like i was hurting the baby even tho no matter what i ate is just wasnt gaining it back until about 2 weeks ago. Alot of people who are obese tend to lose weight early annd then start to gain it back as the baby grows.
One of my best friends did. She wasn't actively trying to though (don't diet when pregnant). She found that she ate the same (as she was already eating for two and hence, that contributed to her being overweight) that simply supporting the pregnancy caused her to lose weight (without a new exercise routine). So, eat healthy, cut out the junk and you should see a weight loss. good luck