male bigger then female? Problems?

Question
My female Chihuahua is 5lbs and the stud is 6lbs.  The studs owner said there wouldn't be problems but now I am worrying about it.  Her mother had no problems giving birth naturally and had a big littler of 6 pups...  My vet checked her out first when we had testing done and said she was of breeding quality and should have no problems.  However I have done research since the mating and I am nervous now for her.  Is it possible to just schedule a cesarian section like humans or am I worrying too much?  We don't even know if she is pregnant yet but I love my baby and couldn't stand to loose her.  I am a registered nurse and have been doing a lot (maybe too much) research on whelping and pregnancy so I feel prepared but nervous for the size difference....  Any reassurance or advice you can give is greatly appreciated.  Thanks.

Answer
Hi. The best thing you can do for your girl is to not put her on puppy food at this time. Keep her on a good food, and make sure she gets plenty of exercise, don't let her get fat. A fat dog has problems during whelping. Every time you breed a dog you take the chance of running into complications. You do the above, and you can help reduce her risk. I do know that your breed is known for c-sections, but it doesn't always have to happen. What you can do is after day 50, have an x-ray done. This will tell you about how many there are, and if there are any really big ones in there that may cause problems. When she starts labor, call your vet to let him know just in case you need him. Good luck, and let me know if I can help with anything else.