Cold wet weather never bothered me...

It's unfair really; it's always the male who gets the blame. The Herald reports:

Early reports from sheep-scanning operators indicate there are more barren ewes in the hills and uplands as a result of reduced ram libido caused by the atrocious weather in late autumn.
Peebles-based Jim Watson scans 60,000 ewes and reckons that normally 5% or 6% of the Blackface ewes in his run are barren.
This year, he says the figure is nearly 10%. "I put that down to the bad weather. The problem is greater where Blueface Leicester tups were being used. They don't take to cold, wet weather and spend a lot of time sheltering. It's not as if there was any shortage of grass last backend," he said.

Well, it might be the effect of the cold wet weather on the rams. But it might equally be attributable to the fact that a lot of ewes get headaches at that time of year...