Using tampons after sex?!

Britney • I'm a happily married to the love of my life and I'm a 27 year old who is graduating university soon this year and is hoping to start having some beautiful babies soon! We have had one pregnancy and miscarriage at 7 weeks so far hoping for a rainbow baby
My friend told me her secret to getting pregnant is to put in a tampon after he ejaculates lol does that work ? Is it safe? Someone also said put a warm water bottle by your vagina after sex and it will make the sperm more mobile lol