Key message
• When comparing long and short treatments with gonadotropin-releasing hormone agonists (GnRHa), there was little or no difference between groups for live births and ongoing pregnancies, but the long treatment may result in a higher clinical pregnancy rate (where the fetus may be seen or heard).
• We are uncertain whether there is any difference in the number of live births and clinical pregnancies for the other comparisons studied, except for the comparison 100 µg dose versus 25 µg dose in a short treatment, which showed that clinical pregnancy can be improved with a 100 µg dose.
• Further research is needed to look at the cost-effectiveness and acceptance of the different treatments.
What did we want to find out?
Gonadotropin-releasing hormone agonists (GnRHa) are given along with hormone injections that stimulate the ovaries to try to prevent the premature release of eggs before they can be harvested in a planned manner using a surgical procedure. GnRHa has been shown to improve pregnancy rates. Different ways of giving GnRHa are described in the literature. We wanted to find out the most effective way to give GnRHa to increase the number of babies born and ongoing pregnancy rates, in addition to reducing the rates of pregnancy loss and ovarian hyperstimulation syndrome (OHSS) (an unwanted effect of treatment with fertility drugs).
What did we do?
We reviewed the evidence on which medications (in the form of GnRHa) are best given together with hormones to stimulate the ovaries for women trying to conceive through assisted reproduction.
What did we find?
We found 40 studies of 4148 women comparing the use of GnRHa in different ways during assisted reproductive treatment. Nineteen of these studies (1582 women) compared a long treatment (where GnRHa is started at least two weeks before hormone stimulation) with a short treatment (where GnRHa is started with hormone stimulation).
Main results
When comparing long and short GnRHa treatment, there was little or no difference between groups for live birth and ongoing pregnancy rates. Our results suggest that in a population where 14% of women achieve a live birth or ongoing pregnancy with a short treatment, between 12% and 30% will achieve this with a long treatment. There is evidence that the long treatment may result in a higher clinical pregnancy rate (where the fetus can be seen or heard) compared to the short treatment. Our results suggest that in a population where 16% of women will achieve a clinical pregnancy with the short treatment, 17% to 32% will achieve this with the long treatment.
For other comparisons of GnRHa treatments, we are uncertain whether there is any difference in terms of live birth and clinical pregnancy rate, except for the comparison of 100 µg dose versus 25 µg dose in a short course, which showed that clinical pregnancy can be improved with a dose of 100 µg.
We are uncertain whether there is a difference in OHSS rates and pregnancy loss, which were reported by only two studies each.
There was insufficient evidence to draw any conclusions about other harmful effects. Further research is needed to look at the cost-effectiveness and acceptability of the different treatments.
What are the limitations of the evidence?
We have low to very low confidence in the evidence. The main limitations of the evidence were non-reporting of live birth or ongoing pregnancy in half of the studies, poor reporting of study methods, unclear findings, very few studies reporting adverse effects such as OHSS and lack of data on other adverse events, cost-effectiveness and acceptability of the treatments. Only eight of the 40 included studies were conducted in the last 10 years.
How current is this evidence?
The certificate is valid until December 2022.
