People in Wales can now get emergency contraception from pharmacies for free but those in the rest of the UK still have to pay around £25.
The move, which also means that under-16s in Wales can be given the 'morning-after pill' if it is deemed clinically appropriate, has sparked criticism from some campaigners.
But ministers said it will help pharmacists to fulfil their role of bringing down unwanted pregnancies in Wales, where parts of the country have some of the highest teenage pregnancy rates in the UK.
The plans were announced by health minister Edwina Hart in November last year. She said she wanted people to be able to access professional advice without an appointment, to make it "easily accessible within the 72-hour time span necessary for emergency contraception to be most effective".
The morning-after pill is free to women across the UK if prescribed by a GP or family planning clinic, but Wales is the first nation to offer emergency contraception without charge on the high street.
Janet Pearce, a nurse adviser at the charity's call centre, said: "It will be particularly beneficial for low income women and young women who may risk a pregnancy because of the cost associated with the emergency contraceptive pill."
"It will reduce unwanted pregnancy but what about the STDs that can be acquired with unprotected sex?" - Nina Anaghara, Essex
"Yes I think so as the younger age woman may find access easier via a pharmacist however one would hope that they would then be signposted to services for reliable ongoing contraception" - Kathy French, London