Is BBT reliable when taking progesterone supplements?

[u/m0onlitdaisy]

I started tracking BBT a few days ago for the first time and this is also my first cycle on Letrozole and progesterone supplements (Duphaston).

Honestly, my BBT is causing me more confusion than reassurance about whether I’ve actually ovulated 😪

My recent BBT:
Oct 2 — 36.20°C
Oct 4 — 36.29°C

Oct 5 — 36.21°C (started progesterone + OPK positive at 5pm)

Oct 6 — 36.31°C + my 1 and only BD at 11:50pm

Oct 7 — 36.46°C (today)

My OPK was getting darker on Oct 5 at 2pm and clearly positive at 5pm.

Would the BBT rise on Oct 7 still be useful for indicating ovulation, or can progesterone supplements cause this kind of temperature rise?

would I have already missed the fertile window by only BD-ing at 11:50pm last night? 😪

[u/CatalystCookie]

Progesterone supplements can cause it.

[u/m0onlitdaisy → u/CatalystCookie]

Do you take bbt when on progesterone supplements? It’s best to skip it ?

[u/CatalystCookie → u/m0onlitdaisy]

I do anyway because I like chatting and want to have a pregnancy chart if and when I get pregnant. But it doesn't actually tell me much lol

[u/Alijanora]

Shouldn't you confirm first ovulation and then start with progesterone? Like around 3dpo? Because if you start before ovulation, you could suppress ovulation by taking progesterone too early. It is one of the functions of progesterone - to suppress releasing of further eggs. If you take it before ovulation, it works like hormonal anticonception.

[u/m0onlitdaisy → u/Alijanora]

I see! Thanks for sharing! I’m not sure too! I followed as per my doctor’s prescription.. I told him my positive OPK is usually cd15/17 but I was asked to take the progesterone supplement from cd 14 to 23.

So because I started earlier before my ovulation, the supplement only enough for until 7-8 dpo which isn’t enough for my luteal phrase right ? 😑

[u/ex-squirrelfriend → u/m0onlitdaisy]

Yeah that seems strange, I'd double check with the doctor in case they made a mistake. I'm supposed to take mine from 3-13dpo

[u/Alijanora → u/ex-squirrelfriend]

Yes, exactly. I don't take it now but on the beginning of the year and I was warned to be sure before taking it that ovulation already occured. I checked my graphs: I started on CD18 both months I was taking it and my ovulation occurred on cd12 and cd13. I took it to regulate my luteal phase as I suffered from luteal phase defect.

[u/m0onlitdaisy → u/Alijanora]

Thanks for sharing! It’s very helpful! The doctor and nurse didn’t mention that I should only start taking it after ovulation 😪 I really hope it doesn’t affect my chances.

I only realised this today since it’s my first time taking it. Now it makes total sense to start only after ovulation! I was instructed to take progesterone from CD14 to CD25, but since I started before my O, that would only take me to around 9 DPO.
The whole point was to help with my short luteal phase.

Oh, and the nurse only gave me 10 pills when I’m supposed to take 12! I’m still waiting for their reply, so hopefully they’ll get back to me soon. 😩

Anyway, have you recovered from your short luteal?

[u/ex-squirrelfriend → u/m0onlitdaisy]

You still had a clearly positive opk so I wouldn't lose hope about this cycle. There's a good chance you still ovulated. I think the main risk of taking it too early is that it could suppress ovulation, so that's something they can confirm for next cycle

[u/Alijanora → u/m0onlitdaisy]

Well, I am not an expert so I definitely cannot tell you how much it influenced your chances. But honestly, I think that I share the opinion with fellow commenter squirrel. The cascade with LH surge was already in the work so probably everything went as usual. You even write you got only 10 pills? So 1 per day? It is not so big supplementation. I personally wouldn't worry 🙏

I took twice a day for 7 days during luteal. Two cycles. It helped with spotting and in general the cycle is not so wonky. Despite this no success yet. Since two cycles with progesterone supplementation I had 8 natural cycles and now I am on second medicated with clomid. Cycle #24 of TTC 🤷 neverending story. I wish you more luck than I have 🙏🤞🍀

[u/Mousehole_Cat]

Any hormonal medication can mess with your basal body temperature. My BBTs were indecipherable when we did IUI but I definitely ovulated.

[u/m0onlitdaisy]

Yeap! I’m checking with them right now.. it realised that the nurse told me to take it from cd 14-25 (total 12 days) but I only received 10 pills 😕 waiting for their reply now! Thanks so much for the information! It’s so helpful!