If TSH was low then perhaps they’re looking into something else related to your thyroid, as in perhaps not hypo? The typical combination for hypo is below normal T3/T4 and above normal TSH. If you just have one but not the other then depending on which one they manage accordingly (eg regularly testing, low dosage levothyroxine etc).
Low TSH is more commonly associated with hyper (overactive) thyroid.
There is a link between discovering hypothyroidism and pregnancy, perhaps because of the increase required in first tri for thyroid hormone production. Baby is sustained by its own thyroid hormone following first tri but uses the mother’s stores until then, for most women this doesn’t come on their radar but if a women is tending towards the lower side, but hasn’t been diagnosed hypo, the baby’s use of thyroid hormone in first tri brings that to light if the mother’s T3/T4 levels or TSH are under greater strain.
So for instance, perhaps the mother isn’t diagnosed hypo and T3/T4 is fine but TSH is going high (above normal). This could be an indicator of the body needing to work harder than usual to produce sufficient T3/T4, which is not necessarily something to worry about but may indicate early stages of hypo/hypo may be a diagnosis in later months or years.
There is also a link between thyroid hormone imbalances and pregnancy sickness. The nature of the link isn’t fully established, but may relate to the chemical similarities between certain pregnancy hormones and thyroid hormones.
Btw I’m no expert on any of this, but I have hypothyroidism (diagnosis 10 years ago) and am in my 3rd pregnancy so I’ve just been around this block a few times!
It’s routine to refer to the consultant for any thyroid results outside of the normal range. Hypo and hyperthyroidism are fairly well understood and easily managed in pregnancy, they’re not typically a cause for concern. I’m sorry you haven’t had more reassurance.
For example, I’m established as having hypothyroidism pre-pregnancy and on levothyroxine. When pregnant my bloods are tested and meds adjusted accordingly. I am referred to a consultant following the booking appointment, see an endocrinologist for about 10-15mins, and then do not need to see them again unless there are any concerns. I have monthly thyroid function tests and meds adjusted as needed, although typically following the first tri they don’t require much in the way of adjustment (because as above, the need for baby’s use of my thyroid hormone diminishes). I’m till technically under the consultant and can request appointments, but discharged from the regular clinic. This is my third pregnancy, and this time around in 2nd tri my TSH has spiked, although T3/T4 is currently fine, so I’ve booked in to see my consultant as that’s less common. I also have HG in this pregnancy so there’s a question mark as to whether there is a link here. However there aren’t any concerns as to the baby or myself, but it is good to check out my results and understand what might be behind them.
As an aside not everyone with hypothyroidism has the classic symptoms, especially if you’re only borderline. I know a couple of women who were diagnosed through routine blood work for medical check ups (like health MOT things) - slim, energetic, not cold or dry skin, for instances, so no reason for them to think anything was going on.
Hopefully you will get your results and appointment soon, but generally speaking this isn’t anything major to worry about. They may continue to test your blood throughout pregnancy, if they feel the need (eg if your blood work showed your levels falling further to below normal or TSH rising further above normal) then they may prescribe levothyroxine - tablets are very small and no major reports of side effects (and I’ve certainly never had any), well researched/reviewed and commonly used in pregnancy. They’ll usually test again within a month or so after birth to see how you’re doing, as dosage usually goes up in pregnancy and reduced again postpartum.