Elevated levels of homocysteine in the blood appear to increase the risk of heart attack, stroke, peripheral vascular disease, and venous thrombo'embolism (blood clots in the veins). Homocysteine is believed to damage blood vessels in several ways.
I don't know for sure about how long Wrens usually spend on the nest at one sitting.. (Sorry couldn't resist the joke) However, the eggs usually hatch in 13-18 days, so if there were no hatchlings when that time elapsed, then you'd know for sure that she hadn't been behaving normally.
The normal incubation period for chicken eggs is 21 days--hatching at 18 or 19 days is too soon, and usually indicates too high of a temperature in the incubator or some other issue. Chicks that hatch too early or too late invariably have health problems or tend to do poorly.t can take anywhere from an hour up to a day for a pipped egg to hatch. Some will pip a bit and then stop for a long time, then finish up all at once in the space of a few minutes. Some will consistently pip until they pop out, within an hour.