WHAT YOUR “NORMAL” BLOODS MAY ACTUALLY MEAN
If you've been trying to conceive for a while and been told your bloods are normal, this might be the most useful thing you read today. If I had €20 for every time I’ve heard that someone’s had all the bloods done and they’re fine, I could probably quit acupuncture (though I wouldn’t want to).
Fertility blood tests are only as useful as the timing and the range of what's being tested. And despite this area getting a lot more air time recently, both of those things are frequently wrong.
The timing problem
One very important mistake is testing FSH, LH and oestrogen along with your other bloods on whatever day you happen to get an appointment. It’s very important that these hormones are tested on days 2-4 of your cycle for them to be reliable - if they were done on any other random day, they don’t really help us for fertility purposes.
Another common error is testing progesterone on day 21 of your cycle regardless of when you actually ovulate. This is based on the assumption that everyone has a 28-day cycle and ovulates on day 14. Most women don't. If your cycle is 32 days, you're probably ovulating around day 18 - which means your day 21 progesterone is being measured just three days after ovulation, nowhere near its peak, and won’t accurately tell us whether you’re ovulating or whether you are producing sufficient progesterone to support a pregnancy. Even if progesterone is tested on the right day, too often the result comes back low but in range and you're told everything is fine. Ideally you need to get progesterone and oestrogen tested 7 days after ovulation (peak plus 7) and they need to be interpreted by a specialist to ensure that they are optimal not just sufficient.
The range problem
Even when bloods are taken on the correct day, "normal" doesn't mean "optimal for fertility." Laboratory reference ranges are population averages. They tell you whether your result falls within the broad range seen in the general population - not whether your hormone levels are at the level needed to support conception.
Thyroid function is a good example. A TSH result of 3.9 might be technically within the normal range, but most fertility specialists would want to see it below 2.5 (and sometimes below 2) for someone trying to conceive. The difference between those two numbers can be significant and the consequences can be not getting pregnant or not being able to maintain a pregnancy.
What's often missing altogether
A standard fertility blood panel typically covers FSH, LH, AMH, oestradiol and progesterone. Occasionally prolactin. What it often misses:
Free T3 and free T4 alongside TSH and thyroid antibodies - a TSH alone is not a full thyroid picture and antibodies need to be tested to check for autoimmune thyroid conditions
DHEA-S and testosterone - important for PCOS and adrenal function
Fasting insulin and SHBG - often missing even when PCOS is suspected
Vitamin D - consistently underestimated in its impact on fertility and implantation
Full iron panel including ferritin - low ferritin can affect egg quality and cycle regularity even when haemoglobin looks normal
What to do with this
I could go on and on about this but I’ve probably already waffled enough to have lost a few people along the way. So if you’re still with me and you've been told your bloods are normal, it's worth asking:
Were my progesterone levels tested seven days after confirmed ovulation?
Has my thyroid been fully tested including antibodies?
Has anyone looked at my fasting insulin and full androgen panel?
Are any of my results normal but very low or high in range?
And I always recommend requesting a copy of your results - people often question whether they’re allowed to - they are your blood results and you are entitled to a copy of them!
None of the above are obscure tests - there are far more we could go into on a case by case basis - they are standard investigations that are routinely missed in a general practice setting, which isn’t designed for the level of individual investigation that actually makes a difference.
You’re entitled to answers, not just empty reassurance. If you'd like to talk through your results and what might be worth looking at further, you can book a free 15-minute consultation or an initial appointment in Skerries or Duleek.
ABOUT ME
SPECIALIST FERTILITY ACUPUNCTURIST. FORMER LAWYER. FORENSIC BY NATURE.
I'M STEPH — AND I CAME TO THIS WORK THE LONG WAY ROUND, VIA A DECADE IN LAW, MY OWN EXPERIENCE OF FERTILITY CHALLENGES, AND A GENUINE OBSESSION WITH FINDING ROOT CAUSES AND REJECTING "UNEXPLAINED" AS AN ANSWER. EVERYTHING I WRITE HERE IS EVIDENCE-INFORMED, HONEST AND WRITTEN FOR PEOPLE WHO WANT REAL INFORMATION RATHER THAN EMPTY REASSURANCE.
