My girlfriend got a visitor visa before she got pregnant, and IHS is not available for Visitor visa. She just recently got pregnant and now we are planning to go to UK.
From what I understood, the baby is considered as an Ordinary citizen if one of the the parent is British. I'm currently working in Thailand but working as expat, employed by a British company. Therefore, I believe she and the baby should be eligible for free NHS if I register the baby as mine at the hospital.
Please refer to page 2 of the following document: birthrights.org.uk/library/factsheets/Foreign-Nationals-and-Maternity-Care.pdf
Please correct me if I misunderstood something. Thanks.