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.
A mother songbird usually lays eggs just prior to or just after sunup, but not all at once. A wren may lay one egg every 24 hours, a dove one egg every two days. The mother eventually will lay a clutch of three or four eggs, sometimes more and sometimes fewer. University of Cambridge researchers discovered a few years ago that mother birds begin communicating with their chicks even before they hatch.