My son and his wife are co sleeping with their new baby. How do I approach the issue of SIDS without causing offence.?

Thank you for contacting Red Nose with your question.

My son and his wife are co sleeping with their new baby. How do I approach the issue of SIDS without causing offence.?

Red Nose does have a comprehensive Information sheet about sharing a sleep surface.
How you approach this discussion is greatly influenced by your relationship with them, however the information sheet may provide some guidelines in relation to the most important information.

Red Nose promotes a risk minimisation approach that educates parent and health professionals about strategies from the best available research to reduce risk in all infant sleep environments and facilitate informed choice to suit a family’s cultural beliefs and environmental circumstance

Sharing a sleep surface with a baby can increase the risk of SUDI. A considerable proportion of SUDI occur on a shared sleeping surface.
Babies most at risk of SUDI when sharing a sleep surface are those less than 3 months postnatal age, babies who were born preterm or small for gestational age.

The risks are always much greater if parents smoke or are under the influence of alcohol or drugs (prescription or illegal) that cause sedation and impair their ability to respond to their baby.
There is a very high risk of infant death, including deaths attributed to fatal sleeping accidents, when a baby shares a sofa or couch with an adult during sleep.

Sharing a sleep surface with a baby is a complex issue that encompasses many factors.
Strategies can be used to reduce the risk in circumstances where parents share a sleep surface with a baby due to parenting preferences, cultural beliefs or unavoidable living circumstances, including instances where a parent may unintentionally fall asleep with a baby.
https://rednose.org.au/article/sharing-a-sleep-surface-with-a-baby