In vitro fertilization for male infertility: when and how?

Can dissenting findings regarding the comparative effectiveness of ICSI and IVF be explained by a learning curve?

PURPOSE

To determine whether between-trial heterogeneity in relative risk of fertilisation for intracytoplasmic sperm injection (ICSI) compared to in vitro fertilisation (IVF) can be explained by learning or by between-trial variation in patient characteristics.

METHODS

Systematic review and meta-analysis of trials comparing fertilisation outcomes for ICSI and IVF (without surgical sperm retrieval). Meta-regressions to identify associations between treatment effect and trial characteristics.

RESULTS

Coefficients on individually significant covariates from the meta-regressions confirm that the ICSI versus IVF treatment effect is increased when patients are "unsuited for IVF" but reduced as semen quality improves and when IVF insemination concentrations are increased. However, the relative risk of fertilisation varies inversely with publication date; contrary to the hypothesised learning effect.

CONCLUSION

While it is recognised that publication date might proxy for unobserved covariates, the possibility of a learning effect in favour of ICSI is not supported by the meta-regression.

Postnatal health and welfare of offspring conceived in vitro: a case for epidemiological studies

In vitro fertilization (IVF) has established itself as an important technique in human assisted reproduction and in livestock improvement. In both humans and livestock the possible long-term effects on health and welfare of offspring born after IVF and in vitro culture to the blastocyst stage are still largely unknown. Epidemiological studies in humans, using data collected for individuals born after normal (i.e. non-assisted) pregnancies, have provided evidence for associations between prenatal life events and adult-life disease. Due to the relatively short time that elapsed since the first IVF baby was born, comparable studies for IVF offspring are not yet possible. However, animal experiments and epidemiological studies with the available data from the livestock industry (mainly dairy cattle) may contribute to a better understanding of the risks involved.