Women’s hormones are constantly shifting and changing, and some of these changes can be mapped out fairly predictably each decade. One of the most important shifts in the 30’s is that your health and hormones are more reactive to stress levels, poor diet, lack of sleep, alcohol and caffeine than in the 20’s, meaning you can’t quite get away with as much without some consequence.
1. Estrogen, progesterone and testosterone are still cycling in a predictable pattern
The length and flow of your period should regular, and ideally somewhere between 27-31 days apart. As you reach your late 30’s, cycles may start coming a little closer together (25-27 days apart).
2. Fertility rates are still good
In most cases, fertility is still quite good through to age 38 or so, as long as your cycles have been quite consistent through this decade. The onset of age-related hormone changes affecting fertility however can vary, and in some cases begin as early as 35. One potential issue with delaying fertility to the mid or late 30’s is that if there are fertility difficulties related to endometriosis, immune issues, PCOS or others, there is a shorter window with good egg quality in which to treat it. That’s why it is generally recommended to start trying to conceive before age 35.
3. Miscarriage rates steadily go up through the 30’s
Miscarriage rates are fairly low under age 35, estimated at less than 15% (after ultrasound confirmed pregnancy). This number approximately doubles by age 40, climbing steadily through the late 30’s to 29% at age 40. (1). The reality is that our eggs are aging, even if we feel healthy and fit.