Assisted reproduction means that when a mommy and daddy cannot have a baby on their own, they go to the doctor to get some help. The doctor has special machines that help the sperm (which comes from daddy) meet the egg (which comes from mommy). When the sperm and egg meet, they make a baby!
Sometimes, the mommy's body cannot get pregnant, so the doctor puts the fertilized egg in another mommy's belly. This is called surrogacy. The other mommy grows the baby and then gives it back to the mommy and daddy, which is super special because then they have their own baby!
There are also ways to help the sperm and egg meet outside the mommy's body. This is called in vitro fertilization (IVF). The doctor takes some of the mommy's eggs and some of the daddy's sperm, and puts them together in a special dish in the lab. The dish is like a cozy home for the sperm and egg to meet each other. After a few days, the doctor takes the fertilized egg and puts it back in the mommy's belly so it can grow into a baby.
Assisted reproduction is like giving a little bit of extra help to make sure a baby can be born. It's like a team effort to make a precious little human!