Strict hygiene practices are followed in the care of newborns, whereas hygiene practices in the care of older babies are less emphasised - HSC - SSCE Biology - Question 20 - 2015 - Paper 1

The best reason for the difference in hygiene practices between newborns and older babies is (D) Early exposure to pathogens helps to build a strong immune system.

Newborns have immature immune systems which require stringent hygiene practices to prevent infections. However, as children grow, their immune systems become more robust, and some exposure to pathogens is beneficial as it helps to enhance immune responses. Thus, the focus on hygiene may be relaxed for older babies compared to newborns.