In short: A woman's fertility depends on regular ovulation, healthy fallopian tubes and womb, and the quantity and quality of eggs, which decline with age, particularly from the mid-30s. Common causes of difficulty conceiving include ovulation problems such as polycystic ovary syndrome (PCOS), blocked tubes, endometriosis, and age. Not smoking, a healthy weight, limiting alcohol and taking folic acid before conception all help. See a GP if you have not conceived after a year of regular unprotected sex, or after six months if you are 36 or over or have a known problem.

This guide, written by a Ready Health prescribing pharmacist, explains what affects female fertility, how fertility problems are assessed in the UK, what tests such as AMH can and cannot tell you, and the options for preserving fertility.

How does female fertility work?

Each menstrual cycle, hormones from the brain (FSH and LH) stimulate the ovaries to mature an egg, which is released at ovulation, usually around 12 to 16 days before the next period. The egg travels along a fallopian tube, where it may be fertilised by sperm, before implanting in the lining of the womb. A problem at any of these steps can make it harder to conceive.

Women are born with all the eggs they will ever have. Both the number and the quality of eggs fall with age, which is why fertility gradually declines, more noticeably after about 35.

What are the common causes of female infertility?

Cause	How it affects fertility	Possible signs
Ovulation problems (for example PCOS, thyroid disorders, high prolactin, being under- or overweight)	Eggs are released irregularly or not at all	Irregular, infrequent or absent periods; with PCOS, excess hair growth or acne
Blocked or damaged fallopian tubes	Egg and sperm cannot meet	Often none; history of pelvic infection (such as chlamydia), ectopic pregnancy or pelvic surgery
Endometriosis	Tissue similar to the womb lining grows elsewhere, causing inflammation and scarring	Painful periods, pain during sex, pelvic pain
Fibroids or womb problems	Can affect implantation, depending on size and position	Heavy periods, pressure symptoms, or none
Age	Fewer eggs and more eggs with chromosomal abnormalities	Longer time to conceive and higher miscarriage risk

In some couples no cause is found, which is called unexplained infertility. Male factors are involved in a large share of cases, so both partners should be assessed.

How can I protect my fertility?

Stop smoking: smoking reduces fertility and speeds up the loss of eggs.
Aim for a healthy weight: being overweight or underweight can disrupt ovulation.
Alcohol: the UK Chief Medical Officers advise not drinking at all if you are trying to get pregnant.
Folic acid: take 400 micrograms a day while trying to conceive and until 12 weeks of pregnancy. Some people need a higher prescribed dose, for example those with a BMI of 30 or more, diabetes, or a family history of neural tube defects, so ask a GP or pharmacist.
Vitamin D: a 10 microgram daily supplement is recommended in pregnancy and is advised for everyone in autumn and winter.
Sexual health: use condoms with new partners and get tested, as untreated chlamydia can damage the fallopian tubes.
Medicines: check with a pharmacist or prescriber before trying to conceive if you take regular medicines.
Have regular sex every two to three days through the cycle, rather than only around predicted ovulation.

Can I test my fertility with a blood test?

Blood tests can give useful information but cannot predict whether you will get pregnant naturally.

Mid-luteal progesterone (about a week before an expected period) can confirm whether you are ovulating.
Thyroid function and prolactin may be checked if periods are irregular.
FSH, LH and testosterone can help assess conditions such as PCOS.
AMH (anti-Mullerian hormone) gives an estimate of ovarian reserve. It is mainly used to predict how the ovaries may respond to IVF medicines. A low AMH does not mean you cannot conceive naturally, and a normal AMH does not guarantee fertility.

Results should be interpreted by a clinician, alongside your cycle history and age.

When should I seek help with fertility?

See a GP if you have not conceived after one year of regular unprotected sex. Seek advice sooner if:

you are 36 or older (after about six months of trying)
your periods are irregular, very infrequent or absent
you have very painful periods or pain during sex
you have a history of pelvic infection, ectopic pregnancy or pelvic surgery
you or your partner have a known condition affecting fertility, or are about to have cancer treatment

Assessment usually includes blood tests, a pelvic ultrasound scan, checks of the fallopian tubes, a semen analysis for your partner and screening for infections. Treatment depends on the cause and may include medicines to help with ovulation (only after specialist assessment), surgery, intrauterine insemination (IUI) or IVF. NHS-funded fertility treatment criteria vary between local areas.

What are the options for preserving fertility?

Egg or embryo freezing can be an option for people who want to delay pregnancy or who need treatment, such as chemotherapy, that may affect fertility. Success rates depend strongly on the age at which eggs are frozen, and freezing does not guarantee a future pregnancy. In the UK, egg, sperm and embryo storage is regulated by the Human Fertilisation and Embryology Authority (HFEA), which publishes impartial information on clinics and success rates. Under current rules, storage can be for up to 55 years, with consent renewed every 10 years.

Women's health and fertility advice in Wigan and Standish

Ready Health in Standish, near Wigan, offers women's health consultations and private blood tests, including hormone checks. A clinician can talk through your cycle and health history, arrange relevant tests, explain your results and help you plan next steps, including referral through your NHS GP or to a fertility clinic where appropriate.

Frequently asked questions

At what age does female fertility start to decline?

Fertility starts to decline gradually from the early 30s and more quickly after about 35, as the number and quality of eggs fall.

Can PCOS stop me getting pregnant?

PCOS is a common cause of irregular ovulation, but many people with PCOS conceive, sometimes with lifestyle changes or treatment to help ovulation.

Is an AMH test worth having?

AMH can estimate egg reserve and helps plan IVF, but it cannot tell you whether or when you will conceive naturally. Discuss what you want to learn from it with a clinician first.

How long should we try before seeing a doctor?

One year of regular unprotected sex, or six months if you are 36 or over. See a GP sooner if you have irregular periods or a known problem.

Key takeaways

Fertility depends on ovulation, healthy tubes and womb, and egg quantity and quality.
Age is the biggest single factor, with a sharper decline after 35.
Stop smoking, aim for a healthy weight, avoid alcohol and take folic acid when trying to conceive.
AMH estimates egg reserve but does not predict natural fertility.
See a GP after a year of trying, or six months if 36 or over; both partners should be assessed.

Sources and further reading

Last reviewed: October 2026 by Shamir Patel, Independent Prescribing Pharmacist, Ready Health. This article is general information and does not replace advice from your own clinician.

If you have questions about your fertility or hormone levels, book a women's health appointment at Ready Health in Standish.