Success rate of IVF treatment
(pregnancy rate)
Since the birth of Louise Brown in 1978, there has been a worldwide steady improvement in success rates of IVF treatments. However, recent data from ESHRE 2011 of the European IVF Monitoring for 2008 appears to have levelled off. The overall pregnancy rate per transfer following IVF was 32.5% and following ICSI 31.9%. Both these rates were slightly lower than those of 2007.
The pregnancy rates vary between IVF clinics, and from time to time within the same clinic. The success of individual IVF clinics may be found in league tables published by HFEA. The overall live birth rate per treatment cycle is about 20%. There are many factors that may affect success rates.
The overall live birth rates for IVF in the United Kingdom have improved from last year from 20.4%. to 21.6%. Overall 23.6% of IVF births resulted in either twins or triplets (HFEA 2006). The success rates are remarkable if compared with the chances of spontaneous conception, which for many couples is very low and for some is zero.
Approximate chances of success of IVF treatment in women aged 38 years or younger in relation to the main steps of the IVF treatment are as follows:
| Ovarian stimulation | 90-95% |
| Collection of the eggs | 99-99.7% |
| Fertilization of the eggs | 90-97% |
| Normal embryo cleavage (division) | 94-98% |
| Implantation rate per embryo | 10-25% |
For most unsuccessful IVF treatments, the cycles appear to have gone well, sufficient number of eggs, good fertilization and easy transfer of good quality embryos. The questions always arise as to why it did not work, and whether further investigations are needed prior to a subsequent IVF cycle, and whether emotional distress such as tension, worry was a contributing factor to their lack of success with their IVF treatment. Dr Boivin and colleagues from UK (BMJ,2011) did not observe any significant association between pre-treatment emotional distress and treatment outcome with assisted conception treatments. In general, there is no apparent reason for IVF failure. However it is useful to consider the following:
- If ovarian response was poor - assess ovarian reserve, and increase the dose of FSH for the next cycle or use different stimulation protocol.
- If sperm quality was poor or there was a poor fertilization rate - ICSI is recommended.
- If endometrial development was suboptimal (too thin or too thick) - investigate the cause and correct before the next cycle.
- If embryo transfer was difficult - the cervix can be stretched under a general anaesthestic early in the next treatment cycle. Alternatively transmyometrial embryo transfer or ZIFT may be employed.
- If there is significant hydrosalpinx - remove or clip the tubes before next cycle.
- If the couple has suffered recurrent failures at IVF (defined as three or more failed IVF cycles) - a full investigation is recommended, particularly assessment of the immune system such as thyroid abnormalities, thrombophilia, increased level of circulating NK cells and elevated Th1:Th2 cytokines ratio. Nevertheless, the role of these abnormalities in recurrent failure of implantation is a matter of debate. Similarly, assessment and uterine blood supply is advocatd b some.