As weird as it sounds, all of us do “hatch” in early embryonic life. The human embryo hatches out of the eggshell (zona pellucida) at the blastocyst stage of development. Assisted hatching involves weakening the zona to facilitate the emergence of the embryo following its transfer into the uterus after IVF. Proponents of assisted hatching suggest that it increases implantation and pregnancy rates.

Assisted hatching can be performed chemically or, more recently, using a laser. In the chemical technique, a dilute acid solution is used to dissolve the external eggshell. Some clinics still perform mechanical hatching, in which a slit is made in the eggshell. Along with many other clinics, we have moved to laser-assisted hatching, in which a laser is used to thin the zona, sparing the embryo from any exposure to the chemicals used in hatching.

There is some controversy regarding which patients benefit most from assisted hatching, and the indications for assisted hatching remain somewhat unclear. Most clinics recommend this procedure in cases where the female partner is older than age 37, has diminished ovarian reserve with increased levels of FSH, or is undergoing a frozen embryo transfer (FET) with previously cryopreserved embryos. Patients who have previously failed IVF following replacement of good-quality embryos may also benefit from assisted embryo hatching.

The risks of assisted hatching are believed to be quite low. There have been reports of increased rates of identical twinning following mechanical hatching (but not after chemical- or laser-assisted hatching). There is no evidence that assisted hatching harms the embryo or causes any increased rate of birth defects in children.

Carol comments:

After my first IVF attempt failed for no obvious reason, the RE suggested that we utilize assisted hatching during our second attempt. We immediately moved into a second fresh cycle and employed assisted hatching. From my perspective, there was no difference. The procedure happened after the egg retrieval, so I was not involved. I did get pregnant during the second cycle, and in theory, the assisted hatching was the primary variable that was different.