The implantation of the embryo into the uterus requires hatching from its zona pellucida (ZP). The inability of the embryo to break its zona pellucida is considered as a factor for implantation failure. Assisted hatching (AH) is performed to make it easier for natural hatching to occur, also providing early embryoendometrium contact, which favors the embryos implantation into the uterus. To evaluate the effect of laser assisted hatching (LAH) on pregnancy rate in frozen embryo transfer cycle.  Materials & methods: In a prospective observational study a total of 80 patients who underwent frozen embryo transfer(FET) cycles were included in the study. Patients were divided into Laser assisted hatching group (LAH) and no LAH group. In the LAH group, zona thinning was done with the help of laser just prior to the embryo transfer. In the control group no hatching was done before transfer. The main outcome measures were pregnancy rate & implantation rate. The baseline characteristics of the 80 patients included in the study ie.,LAH group (n=40) vs no LAH group (n=40),the mean age ( 30.855.4 vs 333.9),mean BMI (25.64.1 vs 27.94.5),duration of infertility ( 6.184.1 vs 8.534.7) , number of embryos transferred (2.750.8 vs 2.70.72) respectively. Younger women < 30 years in no LAH group had higher pregnancy rate compared to the LAH group. Between the two groups, patients between 31-35 years in LAH group had higher pregnancy rate compared to no LAH group. The pregnancy rate (42.85% vs 54.5%) in LAH group of women >35years found lower than the no LAH group. LAH seems to be beneficial in women between 31- 35 years of age group, but LAH does not seem to be beneficial in women > 35 years of age. There is slight increase in pregnancy rates with laser assisted zona thinning in frozen transfer cycle, but it is not statistically significant.

Keywords : Frozen Embryo Transfer, Zonapellucida, Laser Assisted Hatching.