# Natural conception and ovulation induction > Improving the chance of natural conception, when ovulation induction is used, how it is monitored, and its risks and limits, based on current guidelines. Source: https://www.ghinashami.com/en/interests/natural-conception/ Updated: 2026-10-13 Step 2 of 4 · Natural conception Many couples conceive without treatment, and for women who do not ovulate regularly, medicines can help the ovaries release an egg. This page explains what the guidelines advise about trying naturally, how ovulation induction works, and its risks. - 4 min read - Reviewed 13 October 2026 - 5 references ## Trying naturally Most couples in which the woman is under 40 conceive within a year of regular intercourse without contraception, and many of the rest conceive in the second year. Female fertility declines with age, and male fertility does too, to a lesser extent. NICE advises that vaginal intercourse every two to three days optimises the chance of pregnancy. The fertile window is the six days ending on the day of ovulation, and the chance of conception is highest in the two days before ovulation. An ASRM committee opinion notes that urine ovulation tests, which detect the hormone surge that comes before ovulation, have been shown in a randomised trial to shorten the time to pregnancy. General health matters too. Smoking, including passive smoking, is likely to reduce fertility. A BMI of 30 or more tends to make conception take longer, and in women who are not ovulating, losing weight is likely to improve the chance of conception. A very low body weight with irregular or absent periods works the other way, and gaining weight is likely to help. The fertile window: six days 1. 2. 3. 4. 5. 6. Highest chanceOvulation Drawn from the text above. The day of ovulation differs from one woman to another and from one cycle to the next. ## Who ovulation induction is for - Women who do not ovulate regularly because of PMOS (formerly called PCOS). WHO suggests letrozole rather than clomifene or metformin, together with advice on diet, physical activity and weight; see [PMOS](https://www.ghinashami.com/en/conditions/pmos-pcos/). - Women whose ovulation is disturbed by a raised prolactin level, which is treated with cabergoline - Women with hypogonadotropic hypogonadism, in which the brain sends too little signal to the ovaries; reaching a healthy weight and moderating very intense exercise can help, and hormone treatment can induce ovulation Ovulation induction is not a treatment for couples whose infertility is unexplained and who already ovulate. NICE advises against ovarian stimulation on its own in that situation, and WHO suggests a period of trying naturally, with advice on lifestyle and the most fertile days, before other treatment. An assessment of both partners is usually the starting point; see [fertility tests](https://www.ghinashami.com/en/interests/fertility-tests/). ## How ovulation induction works **Tablets.** Letrozole or clomifene encourages the ovaries to mature and release an egg. Intercourse, or sometimes [IUI](https://www.ghinashami.com/en/interests/iui/), is then planned around ovulation. **Injections.** If tablets do not work, hormone injections (gonadotrophins) are the next option in the WHO guideline. NICE advises ultrasound monitoring of the size and number of follicles during this treatment, to reduce the risk of multiple pregnancy and ovarian hyperstimulation, and using the lowest effective dose for the shortest time. **When it does not work.** For women with PMOS in whom tablets and injections have not led to a pregnancy, WHO suggests [IVF](https://www.ghinashami.com/en/interests/ivf-icsi/) rather than continuing to wait. ## Questions worth asking your doctor 1. 1 Am I ovulating? Cycle history and simple tests can show whether ovulation is happening. If it is, ovulation induction is usually not the answer. 2. 2 Which medicine, and how will it be monitored? Ask which medicine is suggested and why, and whether scans will check how the ovaries respond. 3. 3 How long should we try before reviewing the plan? Agreeing on a time frame in advance helps the next decision to be made calmly. Dr. Ghina Shami ## Risks and limits **Side effects.** Ovulation medicines can cause side effects such as hot flushes, headaches, nausea and vomiting. **Multiple pregnancy.** If more than one follicle develops, the chance of twins or more rises, which carries health risks for the mother and the babies. Monitoring is meant to keep this risk low. **Ovarian hyperstimulation syndrome (OHSS).** With hormone injections, the ovaries can over-respond and become enlarged and painful; severe OHSS is rare but can be serious. **Long-term.** NICE notes that no direct link has been found between these medicines and invasive cancer, nor, in the short to medium term, any link with harm to children born after ovulation induction, but that information on long-term outcomes is still awaited. **Limits.** Not every cycle leads to a pregnancy, and trying for a long time can be emotionally hard. NICE advises that counselling be offered to people with fertility problems. ## Common questions **How long should we try before seeking advice?** NICE advises an assessment of both partners if there is no pregnancy after a year of regular unprotected intercourse, and earlier referral if the woman is 36 or older or if either partner has a known or suspected cause of infertility. Your doctor can say how this applies to you. **What are the side effects of ovulation tablets?** Possible side effects include hot flushes, headaches, nausea and vomiting. Ovulation medicines can also lead to more than one follicle developing, which raises the chance of twins; this is one reason the response may be checked by ultrasound. **Is ovulation induction used for PMOS?** Yes. When PMOS (formerly called PCOS) stops regular ovulation, WHO suggests letrozole, together with advice on diet, physical activity and weight. If tablets do not work, hormone injections and then IVF are the next options in the WHO guideline. **Evidence basis:** This page is based on clinical guidelines (NICE 2026, WHO 2025), an ASRM committee opinion and NHS and HFEA patient information; several recommendations rest on low-certainty evidence or expert consensus. ## References 1. Fertility problems: assessment and treatment, NICE (guideline NG257) (2026) — [nice.org.uk](https://www.nice.org.uk/guidance/ng257) 2. Guideline for the prevention, diagnosis and treatment of infertility: summary of recommendations, World Health Organization (2025) — [who.int](https://www.who.int/publications/i/item/B09599) 3. Treatment for infertility, NHS (2023) — [nhs.uk](https://www.nhs.uk/conditions/infertility/treatment/) 4. Optimizing natural fertility: a committee opinion (2022), American Society for Reproductive Medicine (2022) — [asrm.org](https://www.asrm.org/practice-guidance/practice-committee-documents/optimizing-natural-fertility-a-committee-opinion-2021/) 5. Risks of fertility treatment, HFEA (2016) — [hfea.gov.uk](https://www.hfea.gov.uk/treatments/explore-all-treatments/risks-of-fertility-treatment/) Written and reviewed by [Dr. Ghina Shami](https://www.ghinashami.com/en/about/), Consultant, Reproductive Medicine and Infertility · 13 October 2026 · [How these pages are prepared](https://www.ghinashami.com/en/legal/#accuracy)