Assisted Hatching

The first step of pregnancy occurs when sperm fertilize an egg. In cases of natural conception, fertilization takes place in the fallopian tube when you have intercourse around the time of ovulation.
The fertilized egg, now called the embryo, then travels from the fallopian tube into your uterus for implantation. Implantation takes place about a week after fertilization.
If you use IVF to conceive, fertilization takes place outside of your body. After several days, your doctor transfers the embryo into your uterus, where it will hopefully implant and grow. With both natural conception and IVF, the embryo must hatch before it can implant in the womb. To successfully hatch, the embryo must spontaneously rupture through its outer layer, called the zona pellucida.