Pregnant women in Wales are urged to avoid contact with animals that are giving birth, have recently given birth, or have aborted.
Public Health Wales is issuing this guidance due to the risks posed by infections that can occur in some ewes, which may have serious consequences for pregnant women.
Pregnant women and those with weakened immune systems who come into close contact with sheep during lambing may be at risk.
Infections such as enzootic abortion (EAE), Q fever, Salmonella, and Campylobacter can be transmitted, as well as other zoonotic infections including Toxoplasma and Listeria.
Dr Christopher Williams, Head of the Communicable Disease Surveillance Centre, said: "Avoiding close contact with lambing ewes and other animals giving birth is the best way to reduce this risk."