Women’s Health · Fertility

Why Am I Not Getting Pregnant?

Most couples take longer than they expect. Here is where the causes actually sit, when it is time to involve your GP, and what an ultrasound scan can — and cannot — tell you.

Couples hands clasped together on a kitchen table while talking about trying to conceive

If you have been trying for a few months and nothing has happened, the most likely explanation is the least dramatic one: it has not happened yet. NHS figures put it at about 84 in 100 couples conceiving within a year of regular unprotected sex, which means a sizeable minority of entirely healthy couples are still waiting at the six-month mark.

At the same time, around one in seven couples do have difficulty conceiving, and waiting is only sensible up to a point. This page is about telling those two situations apart — and about being honest on what a scan can add, because ultrasound answers some fertility questions well and others not at all.

The Causes

Where the causes actually sit

When conception is delayed, the cause is roughly as likely to sit on either side. In broad terms — and the NHS uses a similar breakdown — about a third of cases relate mainly to female factors, about a third mainly to sperm, and the rest are a combination of both or remain unexplained after testing.

On the female side, ovulation problems are the most common single cause — polycystic ovary syndrome above all, alongside thyroid problems and low body weight or intense training. Structural causes matter too: blocked or damaged fallopian tubes, endometriosis, and fibroids or polyps that distort the womb cavity.

On the male side, it is about the sperm: how many, how well they move, and how they are formed. There are usually no symptoms at all, which is exactly why it gets missed when testing focuses on one partner.

Unexplained infertility is a real and common outcome — everything tested comes back normal and conception is still slow. Frustrating as the label is, it is not a dead end; many couples with unexplained delay conceive without treatment, and there are established routes if they do not.

Timing

The part most people get wrong: timing

The fertile window is short — roughly the five days before ovulation plus the day itself — and ovulation sits about 14 days before your next period, not 14 days after the last one. In a 35-day cycle that puts ovulation around day 21, a week later than the day-14 rule of thumb most apps assume.

If your cycles are irregular, prediction gets worse still, because there is no fixed pattern for an app to project forward. That is one question ultrasound answers directly: a short series of scans across one cycle shows whether a follicle is developing and when it releases, rather than estimating it. Our guide to follicle size by cycle day shows exactly what that growth looks like.

When To Act

When to involve your GP

Your situation When to see your GP
Under 36, no known problems After 12 months of regular unprotected sex without conceiving.
36 or over After 6 months — age moves the timetable, so investigations start sooner.
Irregular or absent periods, known PCOS or endometriosis, previous pelvic surgery or infection, cancer treatment, or known issues on either side Do not wait the year out — go now and say why.

Two things worth saying plainly. Fertility assessment is for both partners from the start — checking one half of the equation wastes months. And semen analysis is arranged through your GP or a fertility clinic; we do not offer semen analysis at IUS London, so if a male factor is the open question, that is the route rather than a scan.

Scans, Honestly

What ultrasound can — and cannot — tell you

Ultrasound can show Ultrasound cannot show
Whether and when you ovulate, tracked across a real cycle rather than estimated Egg quality — no scan or blood test measures it directly
Your antral follicle count, one marker of ovarian reserve Whether your fallopian tubes are open — that needs a specific tubal test via a fertility clinic
A polycystic ovarian appearance, ovarian cysts and endometriomas Anything about sperm
Fibroids or polyps distorting the womb cavity, and the lining’s thickness and pattern Whether an embryo will implant — no test predicts that

That honesty cuts both ways: a normal scan is genuinely reassuring about structure and ovulation, and it still does not rule out tubal, sperm or egg-quality causes. A scan is one instrument in the assessment, not the whole assessment.

Cycle calendar, ovulation test and phone laid out for tracking ovulation
At IUS London

How we can help while you investigate

  1. 1
    Baseline pelvic assessmentA transvaginal scan of the womb, lining and both ovaries, including an antral follicle count — the structural questions answered in one 30-minute appointment.
  2. 2
    Follicular trackingTwo to four scans across a single cycle to confirm whether a dominant follicle develops and when it releases — direct evidence of ovulation instead of an app’s estimate.
  3. 3
    Results you can useFindings are explained on screen as we scan, and the written report is usually with you within two hours — ready to take to your GP or fertility clinic.
  4. 4
    Straight answersIf your question is one a scan cannot answer — tubes, sperm, egg quality — we say so and point you at the right test, rather than book you another scan.
FAQs

Your questions answered

Is it normal to take more than six months?
Yes. About 84 in 100 couples conceive within a year, which means plenty of couples with nothing wrong are still trying at month six or nine. Under 36 with regular cycles and no known problems, a year of trying before investigations is the standard advice.
Can a scan tell me why I am not conceiving?
Sometimes. It can find — or rule out — ovulation problems, a polycystic pattern, fibroids, polyps and cysts, and it measures your antral follicle count. It cannot see your tubes, sperm or egg quality, so a normal scan narrows the question rather than closes it.
Should my partner be tested too?
Yes, from the start. Sperm factors account for roughly a third of cases and usually cause no symptoms. Semen analysis is arranged through your GP or a fertility clinic — it is not something we offer at IUS London.
Does PCOS mean I cannot get pregnant?
No. PCOS is the most common cause of irregular ovulation and one of the most treatable. Many people with PCOS conceive naturally and many more do with straightforward ovulation support — our guide to PCOS and follicular scans covers it properly.
How do I know if I am actually ovulating?
Regular, predictable cycles are a reasonable clue but not proof. Follicular tracking answers it directly: scans across one cycle show whether a follicle matures and confirm when it has released.
When should I skip the waiting and see my GP now?
If you are 36 or over, if your periods are irregular or absent, if you have known PCOS or endometriosis, previous pelvic surgery or infection, previous cancer treatment, or any known issue on either side. In those situations early assessment is the standard advice, not queue-jumping.
Related

Where to go from here

FertilityFollicle Size by Cycle Day

What normal follicle growth looks like, day by day, with the numbers.

Read the guide →AgeTrying to Conceive After 35

What changes with age, what does not, and when to seek help sooner.

Read the guide →TrackingFollicular Tracking Basics

How a tracked cycle runs and what the scan series is for.

Read the guide →

Answers you can act on

A baseline pelvic assessment answers the structural questions; follicular tracking confirms whether and when you ovulate. Findings explained on screen at the appointment, written report usually within two hours — ready for your GP or fertility clinic.

From £159
Follicular tracking scan

Fertility scans

5a Lucerne Mews
Kensington, London W8 4ED
3 mins from Notting Hill Gate

This article is general information about conception and fertility assessment, not individual medical advice. Fertility assessment belongs with both partners and starts with your GP — NHS guidance on fertility problems sets out the pathway, including semen analysis and tubal tests that ultrasound cannot replace.

Written and clinically reviewed by the HCPC-registered sonographers who perform this scan at IUS London — a CQC-registered diagnostic ultrasound clinic (Provider ID 1-2775844974). Your own findings are explained to you at the scan and set out in your report.

Author: Yianni Kiromitis, Senior Sonographer, HCPC RA38415 — over 20 years’ experience in NHS and private ultrasound
Medically reviewed: 9 August 2026