The type of question you are asking here is ambiguous, because #ChatGPT is actually not wrong. I does indeed take 54 (life) months to grow six babies. How much external time elapses is undefined. Bard and Bing are just giving you a more "human" and less logical answer that sounds more correct but introduce an assumption that the women all conceive at the same time. But that was not given in the question.
ChatGPT-4 (#GPT4) avoids this trap and specifies the starting point:
------------------------
Q: If it takes one woman 9 months to grow a baby, how many months will it take 6 women to grow babies? Show your work.
ChatGPT-4
This question seems to imply that the time it takes to grow a baby can be divided among multiple women, but that's not how human gestation works. The gestation period for a single human baby is approximately 9 months, regardless of the number of women involved.
So, if 6 women are each growing a baby, it would still take each of them approximately 9 months to complete the gestation process. They would each be growing their babies concurrently (at the same time), and after 9 months, there would be 6 babies born.
🙂