What happens to oestrogen after ovulation if you become pregnant?
Originally written by Dr Amy Beckley, PhD, founder and inventor of Proov. Updated by femme to remove fixed hormone thresholds that should only be interpreted clinically.
Every menstrual cycle involves coordinated changes in several reproductive hormones. Oestrogen and progesterone both change across the cycle, and their pattern after ovulation differs depending on whether pregnancy occurs.
Before ovulation: oestrogen rises
As follicles develop in the ovary, they produce increasing amounts of oestradiol, the main form of oestrogen during the reproductive years. This rise helps the lining of the womb develop and contributes to the hormonal signal that triggers the LH surge before ovulation.
Urinary E1G tests can reflect a metabolite of oestrogen and may help identify a rising fertile window, but no single at-home reading can prove exactly when an egg will be released.
After ovulation: progesterone rises and oestrogen has a second phase
The corpus luteum
After the follicle releases an egg, it becomes the corpus luteum. This temporary structure produces progesterone and also oestrogen during the luteal phase.
If pregnancy does not occur
The corpus luteum breaks down, progesterone and oestrogen fall, and that withdrawal contributes to the start of menstruation.
If pregnancy occurs
After implantation, the developing pregnancy produces human chorionic gonadotrophin (hCG). In early pregnancy, hCG supports the corpus luteum so it continues producing progesterone and oestrogen.
As pregnancy progresses, the placenta takes over as the major source of these hormones. Oestrogen levels rise substantially across pregnancy and support changes in the uterus, placenta, breasts and other maternal tissues.
Why fixed “implantation ranges” are misleading
Hormone concentrations vary by laboratory method, timing, whether a cycle is medicated and the individual's clinical circumstances. A single universal oestrogen cut-off cannot tell you whether implantation will or will not occur, and it is not appropriate to use a blog threshold to diagnose miscarriage risk.
During fertility treatment, clinics interpret oestradiol alongside ultrasound findings, medicines, follicle development and other results. The expected values can be very different from those in an unmedicated cycle.
What can at-home hormone tracking tell you?
Urinary hormone tests can show patterns in metabolites such as E1G and PdG. They can be useful for cycle tracking, but they are not the same as blood hormone tests and cannot diagnose implantation, confirm that a pregnancy is healthy or replace clinical fertility assessment.
The bottom line
Oestrogen rises before ovulation, remains active alongside progesterone after ovulation, falls with progesterone if pregnancy does not occur, and rises progressively when pregnancy is established. The pattern matters more than trying to compare yourself with one internet number.
