THE odour of disease makes pregnant mice boost their babies鈥� immunity. It is the first proof that social or environmental cues detected by a pregnant mother can alter traits in its babies.
Female mice are attuned to the odour of male mice as it helps them pick a mate. Olivia Curno of the University of Nottingham, UK, and her team housed pregnant mice next to male mice infected with a parasite. A partition meant the females could smell the males but not come into contact to catch the disease.
Offspring of these mice exposed to the parasite after birth cleared the infection up to five days sooner than those of control mice (Proceedings of the Royal Society B, ). They were also less aggressive. The team found that mothers exposed to infected mice had levels of the stress hormone corticosterone twice as high as normal.
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Curno thinks the pregant mice respond to a subtle odour given off by sick animals. The hormone spike could then warn the fetus of disease, and prompt it to invest heavily in its immune system.
This also explains why pups of control mice tended to be stronger. 鈥淚f there鈥檚 no disease, it鈥檚 worth putting everything into fighting, but if there鈥檚 disease it鈥檚 better to invest in immunity,鈥� says Curno.
