Is it true that if your baby has a big head, a natural vaginal delivery is not possible?

There is no definite answer for this issue. Its more about you only get to know after you have tried it out. It also depends on the mommy's built. If mommy belongs to a smaller built, there will be a higher chance of emergency c-sec if she were to try natural delivery due to baby's big head being unable to pass thru the mummy's pelvic bone. If the mommy's belong to the bigger built, there would be a higher chance of delivering vaginally. There is no right or wrong answer for this. You may read more about this in the below link. http://www.storknet.com/cubbies/pregnancy/excf36.htm importantly, always discuss with your gynae what is your plan if things didn't go as plan, what will plan B be.