What is the recommended dosage of Progynova (estradiol) for a patient with primary infertility, mild adenomyosis, and an ovarian cyst, starting on day 4 of the menstrual cycle with an endometrial thickness of 9.4 mm, in preparation for a donor embryo transfer?

Progynova Initiation with 9.4mm Endometrium on Day 4

Continue Progynova 6mg daily for at least 8-10 more days (until day 12-14 of your cycle) before initiating progesterone, regardless of your current endometrial thickness of 9.4mm. 1

Standard HRT-FET Protocol for Donor Embryo Transfer

Your endometrial thickness of 9.4mm on day 4 is already adequate (target is ≥7-8mm), but timing of estrogen exposure duration is more critical than achieving a specific thickness. 1 The protocol requires:

• Continue Progynova 6mg daily for a total of 12-14 days minimum before starting progesterone 1
• This means you should continue estrogen until approximately day 12-14 of your cycle, not start progesterone on a fixed early day like day 9 1

Critical Monitoring Before Progesterone Initiation

Perform transvaginal ultrasound on day 12-14 to confirm: 1

• Endometrial thickness remains ≥7-8mm (yours is already 9.4mm, which is excellent) 1, 2
• Trilaminar endometrial pattern is present 1
• The 11mm ovarian cyst remains stable (likely O-RADS 2, benign, and does not contraindicate transfer) 3, 4

Research shows that endometrial thickness up to 12mm is associated with progressively improved live birth rates (adjusted relative risk 1.07 for 12-14.9mm thickness in frozen cycles with PGT), so your current 9.4mm is favorable. 2

Why 12-14 Days of Estrogen Matters

Starting progesterone too early (before day 12-14) is a common pitfall that risks poor outcomes because: 1

• Most patients require 12-14 days of estrogen priming before adequate endometrial transformation occurs 1
• Embryo transfer timing must be precisely calculated from the first progesterone dose (blastocyst transfer at 117-120 hours after progesterone initiation) 1
• Inadequate estrogen duration compromises endometrial receptivity despite adequate thickness 1, 5

Progesterone Initiation Protocol

Once you reach day 12-14 and confirm adequate endometrial preparation: 1

• Start progesterone 800mg vaginal daily 1
• Schedule blastocyst transfer for 117-120 hours (approximately 5 days) after first progesterone dose 1

Mandatory Single Embryo Transfer

For your donor embryo transfer, only elective single embryo transfer (eSET) should be performed—this is non-negotiable. 6, 7, 3 The ESHRE guidelines mandate eSET for all donated embryo transfers with no exceptions, regardless of: 7, 3

• Your endometrial thickness (even though 9.4mm is excellent) 6, 7
• Presence of mild adenomyosis 7, 3
• The 11mm ovarian cyst 3
• Any previous failed cycles or duration of infertility 6, 7

The rationale is clear: double embryo transfer increases multiple pregnancy risk 30-fold (OR 30.54,95% CI 7.46-124.95), with substantially elevated risks of pre-eclampsia, gestational diabetes, emergency cesarean section, preterm birth, and neonatal complications—risks that would be particularly problematic in a uterus with adenomyosis. 7, 3

Adenomyosis Considerations

Your mild adenomyosis does not change the treatment protocol or contraindicate transfer, but it reinforces the importance of single embryo transfer to avoid multiple pregnancy complications in an already compromised uterine environment. 3, 8 Adenomyosis prevalence is 24.4% in infertile women and 34.7% in those with previous ART failure, so your case is not unusual. 8