It's all about the quality of your eggs. Women's egg quality and availability diminishes with age. There are tests your OB-Gyn can run to check those levels to look at your egg reserves. Some wonen experience early menopause. There's no good "one size fits all" number when it comes to what age that hapoens. For some women it may be 25, for others it may be 40. You can always do egg freezing now, to retrieve your eggs and save them for later. Even if you waited to use them for 10 or 15 years, the eggs will be frozen in time and not age. Women can have healthy, successful pregnancies into their mid to late 40s, (I've even seen some women become pregnant at 52!) but your eggs won't stay good that long. Here's a medically reviewed article you may find helpful. https://www.fertilitywise.com/research/egg-freezing