1. AGE
Woman’s age is the single most important factor. As age increases, all reproductive rates deteriorate, including reduced spontaneous conception and IVF success and increased miscarriage rate. Thus it is strongly recommended to women above 35 years, who have been trying to conceive with no success, to ask for medical help after (only) six months, without waiting the traditional period of one year. In addition, if no childbearing is planned in the immediate future, women getting close to 38 can opt for egg cryopreservation (freezing).

2. SMOKING
Smoking affects (among other things) IVF success rate. It has been calculated that female smokers need twice the number of IVF attempts in order to succeed, than non smokers.

3. INCREASED BMI
Overweight women, and obese women even more, have a lower chance of life birth after IVF and increased chance of miscarriage.

4. IVF UNIT CHOSEN
The Unit chosen does affect greatly the result. Important factors are:
- Individualization: Each couple has different needs and requires specialized treatment. There is a variety of medical protocols for controlled ovarian hyperstimulation, and the ideal one should be chosen for each woman separately. Respectively, there are different methods for in vitro egg fertilisation, which should be considered depending on the sperm parameters and the type of sperm defect (if any).
- Details, details, details. The slightest detail can affect the result. A good example is the method for embryo transfer - many women fail to conceive simply because this procedure is not performed optimally. At the same time, oocyte pickup technique affects the number of eggs retrieved.
- Embryology laboratory condition. Adherence to the rules and protocols, as well as constant quality control and monitoring of specific measures, ensure optimal results.
- Training and academic background, as well as active research participation of doctors and embryologists who operate, can make the difference in all IVF related steps.