This is not scientific so not exactly what you are looking for, but I think I can say from personal experience that not being touched/held as an infant can and

This is not scientific so not exactly what you are looking for, but I think I can say from personal experience that not being touched/held as an infant can and often does have horrible outcomes. I volunteered in an orphanage in eastern europe. The staff did the best they could, but they were severely underfunded. It was the best they could do to feed, change diapers and take care of the most acute medical needs of the large number of infants in their care. Just holding them even for a brief amount of time often was not possible, though they did try the best they could. The results were heartbreaking. Some children did not speak, others constantly cried, most seemed "OK" but had emotional problems that expressed as aggression or other developmental issues. Growing up in an orphanage is never easy, but you could usually instantly tell if a child was born in the orphanage or came there later (even as young as one year with parents made a huge difference). It was one of the most heartbreaking things I've ever experienced in my life, and even more than a decade later thinking about that orphanage makes me want to cry.