My doctor explained that I have an umbilical hernia. I've never heard of this before. I'm pregnant, so I'm wondering, will this require surgery? Is the condition dangerous to me or my unborn baby?
Everyone has an umbilical hernia to some extent. During fetal development, there's a hole in the main supporting layer of the abdomen so that the blood vessels of the umbilical cord can go in and out. After birth, when the umbilical stump falls off, the opening is usually small, but nevertheless remains; however, in some individuals (as you've experience) the opening can remain larger or even get larger under circumstances of increased abdominal pressure, like with chronic coughs or, as in your case, pregnancy.
The only way to actually fix an umbilical hernia is with surgery. But usually the hole will get smaller again after the pregnancy. Surgery is only necessary if it is symptomatic (hurts) or if there's a risk of a loop of bowel being forced out of it and then being trapped so that it won't slip back in. This could strangulate the bowel and mandates a repair, which is usually a simple operation involving looping a purse string of suture around it. This could even be done with an epidural.
So surgery is necessary only when your doctor feels there is risk of herniation of the bowel through it, or if the pain from it is so great as to interfere with your normal daily activity. Otherwise, it can be ignored and addressed—if need be—after the baby's born. If you end up having a C-section, it can fixed at that time!
You can cheat an umbilical hernia by wearing an abdominal binder, which will do no harm, and maybe even delay any surgery until after delivery.