Inside the IVF Lab

Lecture 3 part 4

Topics covered:

• Trigger timing based on follicle size
• Fresh vs freezing all decision (endometrial readiness, hormonal profile)

Two of the highest-stakes timing decisions in an IVF cycle: when to give the trigger shot, and whether to transfer fresh or freeze everything. This episode covers how follicle size determines trigger timing, and the reasoning behind the fresh-vs-freeze-all decision, weighing endometrial readiness and hormonal profile from Episodes 3.2 and 3.3 against the practical benefits of proceeding immediately.

Lecture 3 part 3

Topics covered:

• Embryo-endometrium alignment
• Controlled ovarian stimulation overriding natural cycles

This is the episode where Episodes 3.1 and 3.2 collide.

In a natural cycle, the ovary and endometrium stay synchronised automatically, but controlled ovarian stimulation deliberately overrides the ovarian side, which means the endometrial side can drift out of alignment. We explain what "synchronisation" actually means in practice: matching embryo developmental stage to endometrial receptivity, and the specific ways stimulation protocols can accidentally throw that alignment off.

Lecture 3 part 2

Topics covered:

• Proliferative phase (Oestrogen-driven)
• Secretory phase (Progesterone-driven).
• Window of implantation

While the ovary runs its own cycle, the endometrium is running a parallel one — and the two have to line up almost perfectly for a pregnancy to succeed.

This episode covers the two endometrial phases (proliferative, driven by oestrogen; secretory, driven by progesterone) and introduces the "window of implantation", the narrow stretch of time when the endometrium is actually receptive to an embryo. We frame this as the second half of a two-clock system, with the ovarian cycle from Episode 3.1 as the first.

Lecture 3 part 1

Topics covered:

- Follicular phase dynamics

- Ovulation (LH- triggered)

- Corpus luteum formation

In Lecture 2 we covered the hormones that drive the ovarian cycle, now we walk through the cycle itself, stage by stage.

This episode traces the ovarian cycle as a timeline: a cohort of follicles is recruited, one is selected to dominate, an LH-triggered ovulation releases the oocyte, and the leftover follicular shell transforms into the corpus luteum. We treat this less like new biology and more like watching the hormonal story from Episodes 2.1 - 2.4 actually play out inside the ovary in real time, setting up the rest of Lecture 3, which is all aboutkeeping this cycle synchronised with everything else happening in an IVF cycle.

Lecture 2 part 6

Topics covered:

• Cycle cancellation rate
• E2 levels vs follicle count correlation

Every hormone discussed across this series eventually gets reduced to a handful of numbers on a lab report.

This closing episode covers two KPI threads: cycle cancellation rate as a program-level quality signal, and why E2 levels and follicle count have to be read together rather than separately — a mismatch between them is itself a diagnostic clue. We walk through a real monitoring-scan scenario to show these numbers being used in the moment, not just in an annual report, and close out the full Lecture 2 arc.

Lecture 2 part 5

Topics covered:

• Anovulation
• Premature LH surge
• Luteal phase defect

A cycle can fail for a dozen reasons, but three hormonal failure patterns account for a huge share of them.

This episode covers anovulation, premature LH surge, and luteal phase defect — each one mapped back to the biology from earlier episodes — and walks through a real cycle cancelled mid-stimulation due to a premature surge, including why cancellation, not pushing forward, was the right call. Recognizing these patterns early is what separates a bad outcome from one you saw coming.

Lecture 2 part 4

Topics covered:

• Managing poor responders
• PMOS and OHSS risk
• Agonist vs antagonist protocols

Two patients walk in for stimulation, one barely responds to medication, the other responds so well it becomes dangerous.

This episode takes the biology from Lectures 2.1, 2.3 and turns it into real protocol decisions: what a poor response looks like hormonally, why PMOS patients carry a distinct OHSS risk, and the practical trade-offs between agonist and antagonist protocols.

Every choice here is really a hormonal-axis decision in disguise — this episode makes that connection explicit.

Lecture 2 part 3

Topics covered:

• FSH and follicular recruitment
• LH surge and ovulation
• Progesterone in the luteal phase

Unlike the male system's steady hum, the female axis has to build to a peak, trigger one dramatic event, then completely reorganise — twice a month.

This episode moves through the follicular phase's single-dominant-follicle selection, the LH surge that triggers ovulation, and the luteal phase's progesterone support, then ties all three back to why IVF stimulation protocols exist to deliberately override this natural rhythm. If you've ever wondered why "synchronisation" comes up constantly in IVF, this is where that idea starts.

Lecture 2 part 2

Topics covered:

• FSH and Sertoli cells
• LH and Leydig cells/ testosterone production
• Importance of intratesticular testosterone

A man's blood testosterone can look completely normal while spermatogenesis quietly fails — because the number that matters most isn't in the bloodstream, it's inside the testis itself. This episode traces how FSH acts on Sertoli cells and LH drives Leydig cells to produce testosterone, and why intratesticular concentration runs dramatically higher than what shows up on a lab report. We use a real clinical paradox — a patient on testosterone replacement therapy who becomes infertile — to show exactly why location matters as much as level.

Lecture 2 part 1

Topics covered:

• GnRH pilsatility
• FSH and LH roles
• Negative and positive feedback loops

One hormone, released in pulses every 60–90 minutes, sets the rhythm for almost everything downstream in human reproduction. This episode opens the hormonal arc by walking through the three-level chain: hypothalamus, pituitary, gonads, and the feedback loops that keep it running.

We unpack why GnRH has to be pulsatile rather than constant, how FSH and LH split their jobs once they reach the pituitary, and the one moment the whole system flips from negative to positive feedback to trigger ovulation.

It's the blueprint episode, everything else in this hormonal series is a variation on what gets laid out here.