Hello 

Increased body temperatures result of high environmental temperatures , disease, fever, and any other factor that increases body temperature seriously affect fertility,embryo survival, and fetal development , and another reproductive problems .

read the references in attachment

I don't have an article but I have lots of first hand experience in sheep. I have been told it is due to a change in barometric pressure. 

Thank you for your answeres

I am a veterinary student and I am working on my thesis at the moment, and our question to what extent is the barometric pressure influencing the gestation, or if there is any correlation at all to start with.

Now I need some articles to read up on the background but it is very difficult to find, most of them are about  heat stress and thermo regulation. 

Here is a start: http://www.journalofanimalscience.org/content/90/5/1583.full.pdf

http://www.journalofanimalscience.org/content/90/5/1583.full.pdf