There's a lot of countries we're talking about here (and I'm honestly surprised an adult who has hired someone wouldn't be aware) but from a 5 second DuckDuckGo:
> The only thing the employer has to do is avoid criteria which touch on race, religion, gender, age or disability.
Placing ads limited by gender could still be viewed as limiting criteria. IANAL: go look up lawyers who have discussed ad targeting strategy as being in violation of labour laws many times before.
> The only thing the employer has to do is avoid criteria which touch on race, religion, gender, age or disability.
> Allen M., Esq. Attorney