How do eggs develop in polycystic ovaries during stimulation, and why does monitoring matter?
Polycystic ovaries hold many small follicles, so during stimulation they can either respond slowly or suddenly grow too many at once. The doctor therefore uses a gentle, step-by-step injection plan, often with recombinant FSH or HMG, checks the follicles with frequent scans, and chooses a trigger that lowers the risk of over-stimulation.
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Women with PCOS often hear two things that seem to contradict each other: that they have "too many eggs", and that their ovaries do not release an egg. Both are true, and understanding why explains how stimulation is planned. In this short video, in Hindi, Dr Mayur Pai shows how eggs develop in polycystic ovaries with recombinant FSH and HMG injections, and why the aim is good-quality eggs rather than simply more of them.
What is different about a polycystic ovary?
A polycystic ovary holds many small follicles, often arranged around its edge, each containing an immature egg. In a normal month one follicle takes the lead, grows and releases its egg. In PCOS, hormone imbalances, often linked to insulin resistance, stop any single follicle from taking the lead, so often no egg is released. On a scan the ovary looks crowded but quiet. What a PCOS ovary looks like on ultrasound.
Why is stimulation delicate in PCOS?
Because so many follicles are waiting, a polycystic ovary is very sensitive to the hormones used in treatment. With too little, nothing happens for days. With slightly too much, a large number of follicles can start growing together. The gap between the two is narrow, and it is different for every woman.
Too strong a response brings two risks: a multiple pregnancy, especially in IUI cycles, and ovarian hyperstimulation syndrome (OHSS), mainly in IVF, where swollen ovaries leak fluid into the tummy. Careful planning is mostly about staying inside that narrow window.
Which injections are used?
The injections that grow follicles are called gonadotropins. Two are common:
- Recombinant FSH, a very pure form of FSH made with DNA technology, which allows fine adjustments and is often preferred in PCOS.
- HMG, which contains both FSH and LH.
In PCOS the doctor usually starts gently and increases in small steps only if the scans show a slow response, rather than starting high. The exact medicine and amount are decided for you and adjusted from scan to scan. All the IVF injections explained.
An IVF stimulation cycle with PCOS, step by step
- Day 2 of the period: a baseline scan checks the ovaries and counts the small follicles.
- A gentle start: daily injections begin at a cautious level.
- After about five days: the first check scan. The dose is raised in small steps only if the response is slow.
- As the follicles grow: an antagonist injection is added to stop early ovulation, and scans become more frequent.
- When the follicles are mature: the trigger is chosen with the risk of over-stimulation in mind.
- After egg collection: if the ovaries need time to settle, the embryos are frozen and transferred in a later cycle.
Is the aim different in IUI and IVF?
Yes. In an IUI cycle, the aim is one or two mature follicles. If many more develop, the cycle may be cancelled, or occasionally converted to IVF, to avoid a multiple pregnancy.
In IVF, the aim is a good number of mature eggs for the laboratory, but not an excessive one. More follicles do not always mean more good eggs: in PCOS, follicles often grow at slightly different speeds, and not all of them hold a mature egg on the day of collection.
What are the scans watching?
Monitoring is done with vaginal ultrasound scans, sometimes with a hormone blood test. At each visit the doctor counts the growing follicles, measures their size and checks the lining of the womb. In PCOS, scans are often more frequent than usual, especially as the follicles near maturity, because the response can change within a day or two. These visits are short, but they keep the cycle safe and decide when the trigger is given.
How is over-stimulation prevented?
Three safeguards matter most. The dose starts low and rises only when the scans show it is needed. When many follicles have grown, the doctor can use an agonist trigger instead of the usual hCG trigger, which lowers the risk of OHSS; this option exists because an antagonist was used to stop early ovulation. And if the risk is still high, all the embryos are frozen and transferred in a later cycle, so that pregnancy hormones do not worsen the over-stimulation. Frozen embryo transfer explained.
Can anything be done before treatment?
Yes. Where weight is raised, even a modest loss often makes periods more regular and helps the ovaries respond more predictably. Regular exercise and a diet lower in sugar and refined carbohydrates improve insulin resistance, which drives much of PCOS, and the doctor may add a medicine for insulin resistance where needed. Thyroid and prolactin levels are also checked, because problems there can mimic PCOS or make it worse.
Warning signs to report straight away
Mild bloating is common during stimulation. Call us at once if you have severe tummy pain or swelling, repeated vomiting, breathlessness, sudden weight gain, or you are passing much less urine than usual. These can be signs of over-stimulation, and early treatment matters.
About this guide
This guide is by Dr Mayur Pai, MBBS, MS (Obstetrics & Gynaecology), a fertility and laparoscopy specialist. Pai Hospital in Goa has its own operating theatre and its own IVF laboratory, so the scans, the egg collection, the laboratory work and the embryo transfer all happen in one place, under one team.
Questions, or ready to book?
Have PCOS and starting stimulation, or worried about over-response? Send your question and any reports on WhatsApp to +91 95185 02773. To book a consultation, call Sheetal at our fertility reception on +91 95459 20817; every visit is by appointment. Consultations are held in Panjim, Margao, Mapusa and Vasco.
This article is for education only and is not personal medical advice; please consult your doctor about your own situation.
Your questions
Do women with PCOS produce more eggs in IVF?
Often more follicles grow, because a polycystic ovary holds many small ones. But not every follicle holds a mature egg on the day of collection, so the aim is a safe, good number of eggs rather than as many as possible.
Why is OHSS more likely with PCOS?
Because a polycystic ovary holds many small follicles that can all respond at once. When too many grow, the ovaries swell and can leak fluid into the tummy, causing pain, swelling and, in severe cases, breathlessness. That is why PCOS plans use gentle doses, close scans, a safer trigger and, often, frozen embryos transferred later.
How is the injection dose decided in PCOS?
It is set for each woman from her age, weight, egg reserve and any earlier response to treatment, and then adjusted from scan to scan. In PCOS the doctor usually starts low and increases in small steps only if the response is slow.
Are eggs from polycystic ovaries poor quality?
Not necessarily. Egg quality depends mostly on age and general health. Careful stimulation helps the eggs mature evenly, and managing weight and insulin resistance before treatment can help the ovaries respond more predictably.
Can tablets be used instead of injections with PCOS?
For IUI or timed intercourse, treatment often starts with ovulation tablets, and injections are added only if needed. For IVF, injections are needed, because the aim is to grow several eggs at once under close control.
Or call +91 95185 02773
This page is for general education and is not personal medical advice. Treatment depends on your own examination and reports, so please speak to a doctor about your situation. We do not carry out or offer sex determination of any kind.