A different question about the baby (SPOILER)

I can't imagine anyone letting his/her newborn or young infant be filmed -- very stressful bc of the hot bright lights, the noise on the set, and the presence of strangers, some of whom touch the baby. Yet I'm virtually certain that it was a real baby -- I think special effects weren't advanced enough in 1961 to create a robotic baby that looked authentic.

(I realize that the baby wasn't present during the surgery scenes -- that the shots of the baby were interspersed during editing. But those interspersed shots were filmed at *some* point, with lights and cameraman, and the shots in the incubator involved some person or persons touching the baby.)

Can anyone shed light on this?

"All you need to start an asylum is an empty room and the right kind of people."