The truth about Norethisterone and IVF

Norethisterone can be prescribed prior to IVF treatment, whether using your own eggs or donor eggs. You can take it before FET cycles, too. An alternative to birth control pills, Norethisterone controls your cycle before your main medication.

Norethisterone is a synthetic form of progesterone. This is a vital pregnancy hormone that optimises your uterine environment and sustains your pregnancy. In a natural menstrual cycle, the body starts producing progesterone midway through your cycle.

But fertility patients can have irregular bleeds, making fertility treatment hard to plan. Patients with regular cycles, too, may still want to time their fertility treatment, particularly if they’re travelling abroad for their treatment. Norethisterone makes this possible for both camps.

Birth control pills (BCPs) normally regulate a cycle before the stimulation phase. But BCPs don’t suit everyone. Those over 40, with thrombophilic issues or a migraine history can’t take them.

Why? Because BCPs are less ‘natural’ than Norethisterone. Containing estrogen and progesterone, BCPs trick the body and don’t mimic the natural cycle. Norethisterone, on the other hand, is just one hormone. It fools the body in a much gentler way.

By taking Norethisterone from roughly mid cycle (typically 10 to 15 mg daily) fertility patients can extend (and therefore control) their menstrual cycle. Typically, you can prolong it by up 7 to 10 days – sometimes less, sometimes more.

The medication gives fertility clinics the means to get you to bleed when required. Progesterone levels drop towards the end of a natural cycle. It’s this hormone drop that precipitates the bleed. Taking Norethisterone keeps your progesterone levels high. When you stop taking the pills, the hormone crash brings on your bleed 3 to 5 days later.

Using Norethisterone to time the bleed is less flexible than using BCPs. The latter regulate your cycle from day 2 or 3. But you can’t take Norethisterone for too long. And you start it on day 16 or a bit later.

Very roughly, you need to start Norethisterone about six weeks before your estimated egg retrieval or transfer. You may need to adjust your treatment date if your bleed pattern is not quite aligned to this. The ‘start and stop window’ is narrower.

In summary, Norethisterone is medically safer than BCPs in controlling your bleed before a fertility treatment cycle. But it’s more complicated to time than BCPs. Talk to your clinic to see which bleed-control route is best for you.