A thirty-year-old colleague recently asked me: "If I do a fertility test now, will I know whether I can have children?" It is a logical question, but the answer is more nuanced than she hoped. A blood test gives you a valuable snapshot of your hormonal situation, but it is not a crystal ball.
My conviction: it is precisely that nuance that makes a fertility test valuable rather than frightening. Once you understand what each marker does and does not say, testing gives you grip instead of fear. And that knowledge is best gained before you start.
Why have your fertility tested?
Many women think fertility only becomes relevant once you are actively trying to conceive. But knowing your markers earlier can help you make considered choices about timing, spot conditions such as PCOS or early menopause early, and start the process with more calm. It is proactive, not panicked.
At the same time, honesty matters here. No blood test predicts with certainty whether and when you will become pregnant. What a test does do is give you insight into factors that can influence your chances, so you can act more precisely together with a doctor.
The key markers and what they do and do not say
The table below lists the most commonly measured fertility markers, with what they measure, when to test them, and, just as importantly, what they do not say.
| Marker | What it measures | When to test | What it does not say |
|---|---|---|---|
| AMH | Indication of your egg reserve (quantity) | Any point in your cycle | Nothing about egg quality or whether you will conceive |
| FSH | How hard your pituitary drives the ovaries | Cycle day 2-4 | Can fluctuate per cycle; a snapshot |
| LH | Ovulation signalling; LH/FSH ratio | Cycle day 2-4 or around ovulation | One value says little without context |
| Estradiol | Basal estrogen production and cycle build-up | Cycle day 2-5 | Not a direct measure of fertility |
| Progesterone | Confirms whether ovulation occurred | Cycle day 19-22 (28-day cycle) | Says nothing about egg reserve |
AMH: quantity, not quality
AMH (anti-Müllerian hormone) is the most requested marker among women trying to conceive. It gives an indication of your egg reserve and can be measured at any point in your cycle. But note the key nuance: AMH says something about the number of eggs, not their quality. A low AMH does not mean you cannot conceive; women with a low AMH conceive naturally every day. It can mean your fertile window is shorter. Keep in mind too that the pill can temporarily lower the value, so preferably wait two to three months after stopping.
FSH and LH: the control system
FSH and LH together give insight into how well your hormonal control system works. For the most reliable values, measure them on cycle day 2 to 4. A raised FSH can point to a reduced egg reserve, and an abnormal LH/FSH ratio (often 2:1 or higher in PCOS) can be a reason for further investigation.
Estradiol and progesterone: the cycle in view
Estradiol early in the cycle reflects your basal hormone production, while progesterone in the second half of your cycle confirms whether ovulation has occurred. That confirmation is valuable: without ovulation a natural pregnancy is not possible, and a low progesterone value can be a reason to look further with a doctor.
What a hormone test does not replace
However valuable blood values are, they tell only part of the story. Your fertility is also determined by factors that no blood test measures: the patency of your fallopian tubes, the quality of a partner's sperm, and overall lifestyle. An AMH value, for example, says nothing about whether there is a physical barrier to conception. That is why a blood test is an excellent starting point, but persistent questions almost always call for broader investigation in consultation with a doctor. See the test as a first layer of insight, not the complete answer.
Timing changes everything
The biggest pitfall in fertility testing is wrong timing. Measuring cycle-dependent hormones at the wrong moment gives values you can barely interpret. AMH, TSH and your nutritional status can be measured any time, but FSH, LH and estradiol belong early in the cycle, and progesterone in the second half.
The NHG guideline and Thuisarts.nl use as a common rule that further investigation is warranted after twelve months of actively trying under 35, or after six months over 35. If you have risk factors such as an irregular cycle or endometriosis, you can consult a doctor sooner. An orienting test can always be done, even before you have started.
What do you do with your result?
An abnormal value is not a diagnosis and certainly not an endpoint. It is a starting point for a conversation with your GP or a fertility specialist, who can place your result in the context of your age, cycle and personal situation. If you want a broad hormonal picture in one go, the Fertility Assessment brings the key markers together. For a wider hormone screening you can also look at the Hormones Women panel.
Go deeper in which blood test when trying to conceive, in our explainer on AMH value by age, and in the pillar hormone testing in women.
Autor
