Does body weight affect the ability to conceive?

I can see that weight can be a fertility factor, but I don't think it is a direct cause of infertility. If anything, I think that weight would be more of an issue during and after pregnancy, not an issue in preventing pregnany.

I have been trying to get pregnant for 3 years. My doctor suggested losing weight...for overall health, not just to conceive. I lost 75 pounds - and still didn't gain a baby! When you are overweight, doctors tend to overlook other issues, and diagnose everything as a result of being overweight. I was in a bad accident several years ago and was taken to the emergency room. The doctor came in reading my chart indicating I had neck and back pain, and quickly told me I needed to lose weight to alleviate the pain. "Right," I said, "but what about the SUV that just pushed my car through an intersection, up over a curb, and into a block wall? If I was skinny would I have magically not been injured?" Then he finished reading the chart and saw that I was, indeed in a car accident. "Oh, I see. Let's do some x-rays." He was so quick to send me out the door with a prescription for a nutriionist, when, in fact, my pelvis had shifted!

We all know, or have seen, overweight or obese pregnant women - so weight is obviously not a preventive factor for all.