Q&A: What is assisted hatching?
I just turned 40, and have been trying to get pregnant for seven months with two failed IVF attempts in the mix. I heard something about a procedure that helps a woman "hatch" an egg so it can be fertilized. Does this method exist?
Yes, this method does exist and is referred to by different names: assisted hatching (AH) or assisted zonae hatching (AZH). An embryo is surrounded by a hard protein shell called the zonae pellucida. In order to implant into the uterine lining, the embryo must “hatch” or break out of the zona shell first.
There has been a theory that some women may not achieve pregnancies because of the failure of the embryo to hatch. Several studies have been performed which attempted to find the patients who are most likely to have this problem. Some studies measured the thickness of the zonae on the third day of embryo culture others measured the variation in thickness from one side to the other and still others looked at various groups of patients (older patients, those with multiple failures, high FSH levels, etc.).
There have been numerous studies looking at whether methods to assist the hatching process result in more live births. Various methods have been employed: using enzymes to thin the zonae, puncturing it with a glass pipette, or more recently using a laser to create a small hole.
Some studies have shown a benefit to assisted hatching, some have not. In 2009, a large meta-analysis (study which combines the results of many smaller studies) looked at 28 studies which reported pregnancy outcomes, including 1228 clinical pregnancies in 3646 women. There was no significant difference in the odds of live births in the AH compared with control groups.
It is still possible that AH may improve pregnancy rates on a specific subgroup but there is currently no convincing data that there is a benefit.