In Your 20s And 30s
Puberty is long over (phew!) and your cycle is probably on the somewhat reg. Whether you want kids right now or not, your body is in its baby making prime, which means estrogen is in full effect. “Estrogen is key during these years because it is the hormone responsible for getting the uterus ready for implantation and the growth of the fetus,” explains Dr. Thielen. But depending on where you are in your cycle, estrogen fluctuates — peaking about a week and a half after your period (particularly estradiol).
In And After Your 40s
While menopause typically doesn’t occur until 50-something (the experts interviewed say that 51 is actually the average age), perimenopause can occur up to eight years before a woman’s last menstrual period. Even if that’s not the case, estrogen levels do start to fluctuate dramatically when you hit your 40s, which means you aren’t ovulating like you used to, and you could also see other side effects that weren’t an issue in your estrogen-rich 20s and 30s — a drop in sex drive as well as more vaginal dryness and just-won’t-budge weight, especially around your belly and bottom.