Satoshi Kanazawa, the LSE psychologist behind the research, discussed the findings that maternal urges drop by 25% with every extra 15 IQ points in his book The Intelligence Paradox. In the opening paragraph of the chapter titled "Why intelligent people are the ultimate losers in life", he makes his feelings about voluntary childlessness very clear:
If any value is deeply evolutionarily familiar, it is reproductive success. If any value is truly unnatural, if there is one thing that humans (and all other species in nature) are decisively not designed for, it is voluntary childlessness. All living organisms in nature, including humans, are evolutionarily designed to reproduce. Reproductive success is the ultimate end of all biological existence.
That said then, Kanazawa finds it paradoxical that intelligent women apparently don't possess the desire to pursue what should be the ultimate goal of their biological existence, (hence the loser reference). Read more >>