Endometrial Receptivity
Implantation & Uterine Health

Endometrial
Receptivity

The endometrium is not a passive recipient — it is an active, dynamic tissue that must be precisely prepared for implantation. Understand the four pillars of receptivity and how to optimise each one.

≥8mm
target endometrial thickness
30%
of RIF cases have chronic endometritis
WOI
window of implantation: days 20–24
70%
of endometrial immune cells are uNK cells
The Biology

Four Pillars of Endometrial Receptivity

  • →Adequate endometrial thickness (≥7 mm, ideally ≥8 mm) requires sufficient uterine artery blood flow driven by oestrogen-stimulated angiogenesis. Suboptimal perfusion is a primary cause of thin lining and implantation failure.
  • →Nitric oxide (NO) is the primary vasodilator regulating uterine artery tone. L-arginine (6–8 g/day) is the direct precursor to NO synthesis and has been shown in RCTs to improve endometrial thickness and blood flow velocity in women with thin lining.
  • →Omega-3 DHA/EPA reduces thromboxane A2 production, improving uterine microvascular flow. Target 2 g/day from oily fish or algae-based supplements.
  • →Vitamin E (400–600 IU/day as mixed tocopherols) improves endometrial blood flow by inhibiting platelet aggregation and reducing vascular smooth muscle constriction. Evidence is strongest in women with thin lining after prior uterine surgery.
Evidence-Based Protocol

Core Supplement Stack

L-Arginine
Dose: 6–8 g/day
Nitric oxide precursor — improves uterine artery blood flow and endometrial thickness
Vitamin E (mixed tocopherols)
Dose: 400–600 IU/day
Improves endometrial blood flow; antioxidant protection of endometrial tissue
Omega-3 DHA/EPA
Dose: 2 g/day
Reduces thromboxane A2; improves uterine microvascular flow; supports Treg function
Vitamin D3
Dose: Check levels first; target 100–150 nmol/L
Supports uterine Treg immune tolerance; progesterone receptor expression
Lactobacillus rhamnosus GR-1 + reuteri RC-14
Dose: Daily probiotic
Shifts endometrial microbiome toward Lactobacillus dominance
CoQ10 (ubiquinol)
Dose: 200–400 mg/day
Endometrial mitochondrial support; reduces oxidative stress in glandular epithelium
Endometrial Receptivity — Quick Reference
One-page PDF cheat sheet · Supplement doses, food priorities & action steps
Download PDF
Your Protocol

Action Plan

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Foundation

Optimisation

Ongoing