Ivf stimulation protocols by Dr. Mahalakshmi Saravanan

ART STIMULATION PROTOCOLS

Dr.Mahalakshmi Saravanan Reproductive Specialist Founder DirectorARC Fertility Hospitals

INTRODUCTION

The first IVF baby was born during a natural (unstimulated) IVF cycle.

However, it was soon recognized that the success rate of IVF in natural cycles was low, primarily due to the low number of oocytes retrieved.

Ovarian stimulation using urinary gonadotropins was adopted to deal with this problem, resulting in a significant increase in both the number of eggs retrieved, as well as the success rate of IVF.

With the increasing use of stimulation in IVF cycles, various problems were recognized.

Premature luteinization and failure of synchronous follicular recruitment due to early dominant follicle selection were the two main problems resulting in reduced success rates.

Also, ovulation could occur at any time of the day necessitating intensive monitoring and oocyte retrieval at inconvenient times of the day

Gonadotropin-releasing hormone agonists (GnRHa) were demonstrated to result in pituitary desensitization and successfully dealt with these problems, becoming the next major breakthrough in IVF treatment.

More recently gonadotropin releasing hormone antagonists (GnRHant), which have a similar function but take a shorter period of time to achieve pituitary suppression (and prevent the premature LH surge) are increasing being used for the same purpose.

In the natural cycle, follicular dominance is achieved by the estradiol induced negative feedback on the pituitary gland, causing a decline in FSH below threshold levels.

In IVF cycles, exogenous gonadotropins are used to achieve supra-threshold levels of gonadotropins during the phase of follicular recruitment to interfere with this process of dominant follicle selection and enable multiple follicular recruitment

Pituitary desensitization by using either GnRH agonists or GnRH antagonists, is an important part of IVF stimulation as it eliminates the possible interference by endogenous hormones, enabling synchronous follicular development.

This prevents premature luteinization, and helps to reduce intensive and frequent monitoring allowing control over the timing of oocyte retrieval.

The LH surge is substituted by exogenous hCG, enabling clinics to time oocyte retrieval.