That some women do not want children is not a problem. That they feel pressured to do so is something of a problem. But this is worse:
Not having children isn’t selfish. Not having children is a perfectly rational and reasonable response given that humans are essentially parasites on the face of a perfectly lovely and well-balanced planet, ploughing through its natural resources, eradicating its endangered species, and ruining its most wonderful landscapes. This might sound misanthropic, and it is, but it is also true.
I think that most women do want to have children, especially after they have taken care of babies related to them. But most is not all. Those women who do not want to have children are just as natural as those who do.
The rising percentage of women who do not have children, which Gilbert cites as evidence for her position, is not a good indicator that most of them chose not to, though; for educated women, not having children is more likely a "creeping non-choice" due to finding a husband and economic stability in time.
The attitude that I quote above, though, is literally anti-human, and a much worse problem than women feeling that they ought to want to have children.