Hello, and I hope I can help you today. It will take a while for your OB to figure out why your baby has an enlarged bladder, but i want to first assure you that it has nothing to do with any fluids you received when you had food poisoning. Fetuses get hydration from drinking amniotic fluid, and do make their own urine. If there is a blockage of the bladder opening, then the fetus cannot pass urine and that can cause the bladder to look very large and full on an ultrasound scan. The most common cause of a blocked urinary tract in utero is posterior urethral valves, which are more common in male infants. Of course, if you do an ultrasound when the bladder of the baby is just full, it can be mistaken for an enlarged bladder. So in summary, the enlarged bladder will need further evaluation by your OB but your fluid intake does not affect the baby s fluid intake or production of urine. I hope I was able to answer your question today and that my advice was helpful. Best wishes, Dr. Brown