Birth tourism is not new, it has been a long-standing phenomenon, where some well to do women travel abroad to birth, for the main purpose of gaining citizenship for their baby, this is impermissible in United States. Keep in mind this is not when you may have a pregnancy complication and have been referred for treatment. In 2020, under the new amended regulation, the consular officer reserves the right to deny issuance on B nonimmigrant visa, if they believe your primary purpose of travel is to give birth.
Since children born in US can file for a parent at age 21, it is believed, to have been the reason for birth tourism in recent years. The rise has also led to fraud and increase in birth tourism scams. Be sure not to fall victim.
Before your Visa Interview
If applying for a B visa while pregnant, make sure your doctor gives you a note, referral that might help convince the consular officer that the primary purpose of your visit is for medical treatment, pleasure, or business. Even if you had your visa before pregnancy, ask for a referral or doctors note for arrival at the airport.
Remember, have enough documentation to show as proof of visit beyond birth tourism.
Birth tourism policy was amended in 2020 I believe, and yet to be either updated if any by the new administration so be mindful when applying for B nonimmigrant visa while pregnant