During in vitro fertilisation (IVF) or intra-cytoplasmic sperm injection (ICSI) treatment, fertility drugs are used to stimulate the ovaries to produce more eggs than usual.
These are then fertilised with your partner’s, or a donor’s sperm to create embryos.
Because there is normally a number of unused embryos, some people choose to freeze the good quality unused embryos for use in later treatment cycles or for donation.
More top news
Alton Towers crash victim Leah Washington, who lost a leg as a result of the horrific incident, celebrated her 18th birthday last night.
American Football's first female coach, Jen Welter, is hoping to be an inspiration across the globe after being hired by Arizona Cardinals
Cross-channel services face the possibility of ongoing disruption because of migrant activity in and around Calais.