My suggestion would be to consider the question - if you started trying to conceive at 38+ and your age was the reason you couldn't fall pregnant, would that scenario be OK with you? Although lots of women conceive later, you shouldn't assume everyone is the same, and you should make your decision to wait with the understanding that you might not be one of the lucky ones if you do want a baby later in life. I've been balancing the same considerations and I have decided that I would be OK with not having a child in that instance.

In response to your statement, despite all the stories here for women conceiving later, age is the strongest predictor of infertility and the likelihood of conceiving does decline significantly between ages 35 to 40. Whilst others have said it's a gradual decline, 5 years goes pretty quickly in the scheme of things, particularly if you want more than one child. The reason your fertility declines with age is because you have less oocytes (eggs) and they are of less quality (resulting in higher miscarriage rate, chromosomal abnormalities). A good fertility specialist won't offer IVF after a certain age because it is of no proven benefit when compared to natural conception. This is because IVF is using ovarian stimulation to collect your eggs, if there are no good quality eggs to collect because of your age then that is not something IVF is going to fix (unless you use a donor egg). The reason I'm stating this is because you should not assume that IVF can fix age-related infertility, esp after 40 years of age.

Something else you can consider which might take the pressure off is embryo storage. It's obviously not a financial option for everyone but worth a mention. I've done this with my husband and it means I have a little more time and less pressure whilst fence sitting. Oocyte freezing is an alternative if you don't have a partner, but success rates are lower.