FAQs: Progesterone to prevent miscarriage

I’ve written before about what I did (and didn’t) do differently in my fifth pregnancy, which gave me Edward. The TL:DR version being: I took progesterone, and changed absolutely nothing else/ tried to be as relaxed about all other lifestyle minutiae as possible. More than two years on from that post, the questions I get asked the most over email and in my Instagram DMs (always incredibly politely) are still about progesterone. How much did you take? For how long? Did you pay for it? So I thought I would put all the answers together, here, for anyone out there wondering and searching.  

(To be absolutely clear, I am not a doctor and this post should not be taken in place of medical advice. This is information about my own personal circumstances, informed by what I’ve learnt from interviewing doctors and researchers over the years in my job as a health journalist. What I do know is how desperate and lonely it can be trying to work out what to do after miscarriage, especially multiple, unexplained miscarriages. I also know that the support and medical advice you get after pregnancy loss is not always as all-encompassing and pro-active as you’d wish. So I sincerely hope this Q&A brings a glimmer of clarity in a dark and confusing time, and perhaps serves as a useful primer ahead of speaking to your own doctor or medical team.)  

Here we go…

Q. Why progesterone? 

A. Progesterone is an essential hormone for pregnancy. It’s released from the ovary at first, then the placenta takes over later on in pregnancy. It’s the ‘pro-gestation’ hormone, if you like. It’s been trialled and tested as a medication to prevent miscarriage for decades, without much conclusive evidence. Then, in 2019, a high quality, multi-centre trial of more than 4,000 UK women found that it did seem to significantly increase the live birth rate in a sub-set of women who’d had had three or more miscarriages and had started bleeding again in a subsequent pregnancy. These trial results were published after my fourth miscarriage, and so when I was pregnant again, I decided to ask my doctor at the recurrent miscarriage clinic if it was worth trying. They agreed. It was prescribed for me, for free, on the NHS.

I hadn’t been tested for ‘low progesterone’ specifically, or anything like that – in fact, all the medical tests we’ve had have been normal, putting us in the 50 per cent of people affected by recurrent miscarriages whose losses are unexplained. (See the final question below about how/why progesterone might work.) 

Since then, in November 2021, the UK’s National Institute for Health and Care Excellence (NICE) updated its guidance on miscarriage and now officially recommends that progesterone should be prescribed for anyone who starts bleeding during pregnancy if they’ve had at least one previous miscarriage.

On this basis, I actually still wouldn’t have met the required criteria for being prescribed progesterone, as I wasn’t bleeding – but I know some experts believe that if you have had two or more miscarriages it is at least worth asking your doctor about, bleeding or not. 

Q. How much did you take? 

I followed what was given to people who were enrolled in the 2019 trial mentioned above – known as the Prism trial. That meant 400mg of micronised progesterone as a vaginal pessary twice a day. 

Q. How long did you take it for? 

I started taking it after I found out I was pregnant, from 7 weeks, simply because that was when we had our first appointment and scan in that pregnancy at the recurrent miscarriage clinic, so it was my earliest opportunity to ask about it. I stopped taking it just after 16 weeks. Again, this was in line with what happened in the Prism trial. That said, I was very nervous about stopping. And although my consultant said there was no evidence that taking it beyond 16 weeks is necessary or that there’s any harm in stopping straight away once you get to that point, I did (perhaps superstitiously) slowly reduce the amount I was taking over the course of a couple of weeks from 16 weeks (one a day, then every other day etc.) until I’d used up the last packet of pessaries I had. 

Q. What kind did you take? 

I took Cyclogest, which is the same active ingredient/type of progesterone that was used in the Prism trial, although not the exact same brand (participants took a brand called Utrogestan). This is a pessary or suppository, and it can be taken vaginally or rectally. (Side note: I will never forget the look on Dan’s face when we collected the prescription from the hospital pharmacist and he realised exactly how the medication had to be taken. The sweet summer child.) 

Both Cyclogest and Utrogestan are a kind of progesterone known as ‘micronised’ progesterone, this means that although it is a synthetic hormone, the molecules are identical to the progesterone the body produces naturally. It is sometimes referred to as ‘body-’ or ‘bio-’ identical. They are not new drugs. This kind of progesterone is also sometimes used as part of HRT for menopause and for transgender women, and sometimes as part of IVF treatment.        

Q. Did it have any side-effects? 

There are a few side-effects linked with taking extra progesterone, often PMS type symptoms, like bloating, sore breasts, and headaches. Personally, I didn’t notice anything I wouldn’t have otherwise attributed to being pregnant. I felt essentially the same as I did in all my other pregnancies during the first trimester.

However, there was one big stand-out side-effect. I started bleeding *after* I started the progesterone, at 8 weeks pregnant. Needless to say, this was horrible and frightening and I automatically assumed I was having another miscarriage. The bleeding looked very similar to the way two out of four of the previous losses began. I now know that progesterone like this can occasionally cause vaginal bleeding, and after a scan showed all was OK, that was what my doctors assumed must have been going on. However, I hadn’t been warned ahead of time that this might happen. I really wish I had been.

There are other un-glamorous realities of taking this kind of progesterone – the pessaries are made of hard fat, which dissolves inside the body, allowing the hormone to be absorbed, but there can be some residue (white, creamy, sticky) which can make a real mess of your underwear. Though, to be honest, after assuming for a week or so that I was miscarrying for a fifth time, this was the least of my worries. 

More seriously, the biggest argument voiced against giving progesterone to prevent miscarriage is that there isn’t any specific long-term data on side-effects, such as birth defects (for example). This is not a small consideration. Though the kind of progesterone we’re talking about has been used for quite a while in other situations, including in IVF pregnancies. And while there isn’t enough evidence yet to completely rule out rare adverse effects, NICE notes that there is no evidence at all of harm to either the person taking it or to the baby.

Q. Did it work? 

This is the million-dollar question. And the entirely unsatisfactory answer is: I don’t know. On the one hand – and most importantly – Edward was born alive and well from my progesterone pregnancy. So, clearly something was different this time around. Whether it was the progesterone that made that difference, though, is a lot less clear. It might be that it made no difference and this was just the first time we had a genetically viable, healthy embryo in play. 

Even if progesterone *did* make the difference this time, it’s also hard to say why that might be – while progesterone is known to be vital for pregnancy, it’s not known how exactly it works to help sustain a pregnancy in people with a history of miscarriage. It’s not – for example – necessarily as simple as topping up a low level of natural progesterone. To my knowledge, I’ve not had my hormone levels tested at any point. There are no outward signs that I don’t produce enough progesterone naturally. I don’t have short menstrual cycles or a short luteal phase (the time between ovulation and period starting), for example. 

It’s also clear from the research that progesterone cannot prevent all miscarriages.

What I do know is that taking it during my fifth pregnancy helped massively with my mental health, sustaining my ability to cope with the weeks of tense uncertainty, especially in the first trimester. It helped to know we were at least trying something new. Although it never allowed me to believe ‘oh it will definitely work this time’, I could at least tell myself that even if it didn’t make a difference, if I miscarried again, we would have acquired a small piece of new information. 

With this in mind, I know I would ask for it again were I to have another pregnancy. Indeed, one of my biggest anxieties about trying for another child is how we would feel should I have another miscarriage even though I took progesterone again. It would feel, I think, like having our one (very threadbare) comfort blanket ripped away. 

It’s a little like Dumbo’s feather. It might be an illusion, a confidence trick, my body may not in fact need the progesterone to stay pregnant – but I need the idea of it in order to step off the ledge and try. 

Useful links

In case you are intending to discuss any of this with your doctor, here are some useful links to the published research and the current UK guidance that might assist with being taken seriously.

The updated Nice guidance.

The original published paper from the 2019 Prism trial.

A 2018 Cochrane review on progesterone to prevent miscarriage, which looked at all the available published data at the time, and suggests there may be some benefit for people with unexplained recurrent miscarriages (some trials included in the review counted ‘recurrent’ as two or more, while others classified it as three or more).

Tommy’s, the pregnancy and baby loss charity, funded the Prism trial – as it does a lot of other research in this area. You can read more about their work here. They are also a good source for reliable pregnancy information.

You might also like…

This post on my experience of having tests for recurrent miscarriage.

Can miscarriage be prevented? Trying to answer this question, I wrote this