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Ovulation induction: helping the ovaries release an egg
Ovulation induction is a treatment that helps the ovaries release an egg each month when they do not do so on their own, as often happens with PCOS. It usually starts with tablets such as letrozole, with scans to watch the egg grow and timed intercourse or IUI around ovulation.
Who is ovulation induction for?
It suits women who do not ovulate regularly. The usual signs are irregular or absent periods, and PCOS is the most common cause. Before treatment starts, the doctor usually checks that at least one fallopian tube is open and that the husband's semen analysis is reasonable, because the treatment only helps if the egg and the sperm can meet.
Ovulation induction medicines
- Letrozole is a tablet taken for a few days early in the cycle. It is now a common first choice, especially in PCOS.
- Clomiphene is an older tablet that is still used for some women.
- Injections (gonadotropins) are used when tablets do not work. They need closer monitoring, because they can make more than one egg grow.
Your doctor decides which medicine suits you and for how long. Please do not take these medicines on your own: the doses and the timing are set for each woman.
Follicle-tracking scans
A follicle is the small fluid sac in which an egg grows. A series of ultrasound scans, often called a follicle study, follows its growth over a few days. The scans show whether an egg is ripening, when ovulation is close, and whether too many follicles are growing at once, in which case the cycle may be stopped to avoid twins or more.
In these videos our fertility specialist shows follicle growth on the scan during ovulation induction.
The trigger injection and timing
When a follicle reaches the right size, an injection may be given to trigger the release of the egg about a day and a half later. Intercourse is then timed around ovulation, or an IUI is planned for that window.
How many cycles?
If ovulation happens with treatment, it is often tried for a few cycles. If there is still no pregnancy after several ovulatory cycles, or if ovulation does not happen, the plan is reviewed. The next step may be IUI, injections, or IVF.
Possible side effects
- Hot flushes, headache or mood changes with the tablets, usually mild.
- Twins or more, which is why scans matter.
- Rarely, with injections, over-stimulation of the ovaries (OHSS): seek help at once for a swollen, tight belly, breathlessness or passing very little urine.
Letrozole and clomiphene
Both are tablets, usually given for five days starting soon after the period begins. In PCOS, letrozole is now usually tried first. The two work in different ways but reach the same end: letrozole briefly reduces the body's estrogen, and clomiphene stops the brain from sensing it, so in both cases the brain sends out more of the hormone that grows a follicle. Because clomiphene can make the lining thinner in some women, the scan looks at the lining as well as the follicle.
Is ovulation happening?
- A scan shows a follicle growing and then collapsing after ovulation.
- A progesterone blood test about a week before the next period shows whether ovulation took place.
- Home ovulation kits detect the hormone surge before ovulation; they can help, but they can be misleading in PCOS.
Looking after yourself during treatment
A healthy weight, regular activity, folic acid and not smoking all help the treatment. Keep a simple diary of period dates, tablet days and scan days, and bring it to every visit.
When to move on
If ovulation happens on tablets but pregnancy does not follow after several cycles, or if the tablets do not make you ovulate even after the dose is adjusted, your doctor will look at the next step. That may be injections, IUI, or checking the tubes and the semen report again. See our page on injections for ovulation in PCOS.
Ovulation induction is often the first step for PCOS. It is usually simpler and gentler than IVF, but it only works when the egg and the sperm can meet naturally or with IUI.
Questions about ovulation induction
Is letrozole safe for getting pregnant?
Letrozole is widely used in ovulation induction treatment under a doctor's care, especially in PCOS. It is taken for a few days early in the cycle, and your doctor checks with scans how the ovaries respond.
How do I know if the tablets are working?
Follicle-tracking scans show whether an egg is growing. A period on time suggests ovulation, and a progesterone blood test about a week after ovulation can confirm it. Your doctor reads these together.
How many cycles of ovulation induction should we try?
Usually a few ovulatory cycles. If there is no pregnancy after several cycles, or ovulation does not happen, the plan is reviewed, and IUI, injections or IVF may come next.
Can ovulation induction cause twins?
Yes, it can, because more than one egg sometimes grows. Scans help spot this, and the cycle may be stopped if too many follicles grow.
Do I need ovulation induction if my periods are regular?
Usually not for ovulation itself, because regular periods most often mean regular ovulation. It is sometimes combined with IUI for other reasons, which your doctor will explain.
Can I buy these tablets and take them myself?
Please do not. The dose, the days and the scans are set for each woman, and taking them without monitoring can cause twins or other problems.
How can I tell if I ovulated on letrozole?
A follicle-tracking scan, or a progesterone blood test about a week before the next period, shows whether ovulation happened.
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What you read here explains fertility care in general terms and cannot replace a consultation. Decisions about your own care should be made with a doctor who knows your history and has seen you. We do not carry out or offer sex determination of any kind, which is prohibited by law in India under the PCPNDT Act.