Over 5,000 pregnant Russian women have arrived in Argentina in recent months, including 33 on a single flight last Thursday, the BBC has reported.
All were in the latter stages of pregnancy, according to the national migration agency, and they are travelling to give birth in order to obtain Argentinian citizenship.
Of the 33 women who arrived in the Argentinian capital on one flight on Thursday, three were detained because of document problems, joining three more who arrived the previous day, migration agency head Florencia Carignano told La Nacion.
The Russian women had initially claimed they were visiting Argentina as tourists, she said.
"In these cases it was detected that they did not come here to engage in tourism activities. They acknowledged it themselves."
She said the Russian women wanted their children to have Argentinian citizenship because it gave more freedom than a Russian passport.
"The problem is that they come to Argentina, sign up their children as Argentinean and leave. Our passport is very secure across the world. It allows [passport-holders] to enter 171 countries visa-free," Carignano said.
Having an Argentine child also speeds up the citizenship process for parents. As it stands, Russians can travel visa-free to only 87 countries.
The war in Ukraine has added difficulty to travel for Russians within the EU, as visa agreements were suspended.
La Nacion reported that "besides fleeing war and their country's health service, [Russian women] are attracted by their [right of] visa-free entry to Argentina, as well as by the high-quality medicine and variety of hospitals".
"Birth tourism" by Russian citizens to Argentina appears to be a lucrative and well-established practice.
The BBC reports on a Russian-language website which offers various packages for expectant mothers who wish to give birth in Argentina, including birth plans, airport pick-ups, Spanish lessons and discounts on the cost of stays in "the best hospitals in the Argentinian capital".