Medication Overview: Stims, Trigger, Progesterone

What They Are, Why They Matter, and What It Really Feels Like to Take Them

If you’ve never done IVF before, the idea of injecting yourself can feel terrifying. You picture giant needles, complicated instructions, and your partner holding the leaflet upside down while you panic.

Then the medication actually arrives…and suddenly your fridge looks like a mini pharmacy, there are sharps bins on your kitchen counter, and you’re thinking, “How is this my life now?”

Let’s look at what each medication does, why it’s necessary, and what it honestly feels like to take it.

Stims: The Medications That Help Your Ovaries Step Up Their Game

Stims (stimulation medications) are the injections you take each morning/evening for around 8–14 days.

Their job is simple: grow more follicles than your body would naturally grow on its own.

In a normal cycle, your body selects one egg, maybe two, if it’s feeling ambitious (although more have been known to be selected – hello multiple pregnancies).

In IVF, we’re encouraging your ovaries to mature several eggs at once - because the more eggs retrieved, the more chances you have of getting embryos.

Stims do not create new eggs. They simply help the eggs you already have grow together instead of one at a time.

The names might sound intimidating - Gonal-f, Menopur, Fostimon, Bemfola, Pergoveris - but they’re all doing the same job: telling your ovaries, “let’s do a team effort this month.”

These all contain follicle stimulating hormome (FSH), with some also containing hcg or LH, as these can help mature the eggs, especially in older women.

What Stims Feel Like

Most women find stim injections manageable - not painless, but quick. A tiny sting, a bit of pressure, maybe slight bruising.

For some, the real sensations come later: a heavy, full feeling in your lower stomach, bloating, tenderness, slight breathlessness when your follicles are growing well, and emotions that swing like a pendulum.

I was one of the lucky ones who did not experience any physical side effects from the medication, and you may be the same and wonder what all the fuss is about. I also didn’t experience any mood swings.

If you are one of the ones that experiences the side effects (and its more likely if you have a high number of follicles), some nights you’ll feel absolutely fine. Other nights you’ll look at your belly thinking, “I feel six months pregnant with follicles.”

Both are normal.

Preventer Medications: The “Don’t Ovulate Yet!” Injections

Halfway through stims, your clinic will add another injection - Cetrotide or Orgalutran. This one is to stop you from ovulating early. You might also hear it called a GnRH agonist. It works by blocking the release of LH and FSH.

These injections can sting more (everyone complains about Orgalutran), but they’re essential. They definitely made my leg itch for an hour or so afterwards. But it was manageable.

Blood Tests & Scans: The Monitoring Phase

During stims, you’ll have several scans and sometimes blood tests to check how your follicles are responding.

Some clinics don’t offer blood tests and rely on the scans only. My clinic also checked my oestrogen and LH levels throughout a cycle and it preferred this approach as it gives you more information. There are some clinics that rely on hormone levels to tweak your medications each day.

This is the part where you live at the clinic. You start recognising the staff, you start judging the quality of their waiting room magazines.

Most clinics start early so you can have a scan before work if needed. My clinic started at 7;30 in the morning but every clinic will be different.

The Trigger Shot: The Injection Everyone Fears (Unnecessarily)

The trigger injection is the moment that flips everything from stimulation to preparation. It matures your eggs and controls exactly when they’re ready for retrieval.

It’s usually an injection that contains hcg unless you are at risk of OHSS (Ovarian Hyperstimulation Syndrome). Hcg can trigger OHSS and therefore doctors prefer to give to a GnRH agonist injection instead, such as Lupron, or Buserelin. Hcg is a very similar protein to LH and helps mature your eggs and loosen them from the follicle wall ready for egg collection. GnRH agonist injections trigger you to have your own LH surge, like you would have in a natural cycle. Sometimes you might use both, called a “double trigger”, your doctor will decide what is best for you.

Some of the hcg injections include:

• Ovitrelle

• Pregnyl

• Gonasi

  
  

Some of the GnRH agonists include:

• Lupron

• Buserelin

• Supercur (nasal spray)

• Prostap

• Decapeptyl

  
  

The timing is precise: normally 36 hours before egg collection. With a hcg trigger, the understanding is that you would ovulate between 36-38 hours later (some say 38-40 hours) so the doctors want to wait until as close as possible to the start of this window to ensure your eggs are ready to come away from the follicle wall, but not too late that you risk ovulating before the procedure.

Women often panic about this injection because it feels like the most important one -and it is.

But the good news? It’s usually the easiest one to take. A tiny jab. Done in seconds.

But you are bound to feel a little anxious. Even after 10 rounds of IVF, I had to double check the time the nurses had given me “just to make sure.” So don’t feel like a freak If this is also you, it’s normal!

And then the countdown begins.

You go to bed knowing exactly when your eggs will be collected. It feels surreal, emotional, nerve-wracking… and exciting.

You might feel a bit lost the day after when there are no injections to take. It can take the mind a few days to adjust to the daily routine without jabs. But this is the time to relax as you wait for egg collection.

Progesterone: The Hormone That Holds Everything Together

After egg collection - if you are having a fresh transfer - progesterone becomes your new best friend.

Progesterone is the hormone that supports implantation; it thickens your uterine lining, stabilises it, nourishes it, and keeps it ready for an embryo.

In IVF, your body often needs extra progesterone support because your ovaries have been drained of follicles and your hormones need a little boost. It is thought that the egg collection procedure can damage those follicles and so they aren’t as good at producing progesterone once they turn into corpus luteums.

Progesterone can come as:

• Vaginal pessaries

• Gel

• Intramuscular injections (the big needles used more in the US)

  
  

Most UK clinics use pessaries; they’re messy, they leak. And they are definitely not glamorous.

You’ll learn quickly to use pantyliners, and accept that progesterone has zero respect for your daily schedule.

Progesterone side effects include:

• Sore breasts

• Bloating

• Tiredness

• Mood swings

• Symptoms that feel suspiciously like pregnancy (cruel, but normal)

  
  

It’s a challenging medication - not because it’s painful, but because it makes the wait emotional and confusing.

But it’s also what helps your body hold onto that carefully placed embryo.

The Most Important Thing to Know

Together, the meds create the conditions your body needs - the hormonal environment, the timing, the support - to give you the best possible chance.

You don’t have to understand every detail. you just have to keep going, one injection at a time, one day at a time.