This statement was vague - but the reason I think this is based on the rate of change in technology. Given how traumatic childbirth can be for the female body, how infant health is progressing (babies are getting bigger) and the current trend of some aspects of consumer vanity and certain subsections of feminism - I can see the development of an external synthetic womb being very likely within a few hundred years. I don’t think take up will be ubiquitous, but I do think it’ll be higher than we’d initially imagine. This is what dystopian writers do all day! :o)