While it can happen naturally, many women and celebrities who are having babies over 40 are using assisted fertilization techniques and over 7 million women to date have in the USA. Not acknowledging this to some degree, can portray a false sense of security that this is possible for all women to conceive naturally in that age group.
While there isn't a timeline on how long a woman may be single waiting for real love, there is a timeline on her fertility. This varies and some women in their late 30s may have good numbers, while some in their late 20s may have poor numbers. Knowing helps you know.
With discouraging news, I recommend at least 2 opinions. My husband and I saw 3 reproductive specialists and each had their own view, own mannerisms, and own recommendations. We liked things about each of them, but were surprised at how different they were. So, don't stop at one.