China’s falling birth rate is weighing on heavily on The a2 Milk Company as women delay their pregnancies to get vaccinated, adding to the woes of the infant formula company and triggering and a big profit slump and a 12 per cent plunge in its share price.

Chief executive David Bortolussi said China’s recently introduced third child policy - aimed at getting Chinese couples to have more children - could take many years and even decades to have an impact on society.