Caesarean section (C – section)

Where the baby is surgically removed from the mother’s womb by cutting through the abdomen.

Cell division

A process by which a cell, called the parent cell, divides into two cells, called daughter cells.

Cerebral cyst

A thin-walled abnormal sac or cavity in the brain, containing fluid.

Cerebral hydrocephalus

A condition in which fluid accumulates in the brain.

Cerebral palsy

A condition where parts of the brain are damaged, usually through lack of oxygen, often during the process of birth or when a premature baby cannot breathe properly, which affects the person’s control over muscle movements. It is not progressive (i.e. it doesn’t get worse as time goes by) and it does not necessarily affect a person’s cognitive development or intelligence.


Refers to the connection between the fetus and the placenta in twin pregnancies. Monochorionic twins share a placenta. Dichorionic twins each have their own placenta and gestational sac.

Cleavage stage embryo

An embryo that has developed for 2 - 3 days after fertilisation.

Cochrane review

A review by the Cochrane Collaboration, an international not-for-profit organisation providing up-to-date information about the effects of health care. It regularly reviews the available evidence on health care interventions in order to facilitate evidence-based medicine. 
Cochrane Collaboration website

Code of Practice

A Code issued by the Human Fertilisation and Embryology (HFEA) containing guidance and rules for fertility and research centres. The Code can be found on the HFEA website.
Human Fertilisation and Embryology website

Cohort (observational) study

Study of a group of people with shared characteristics, normally after a health care intervention you wish to evaluate.

Congenital malformations

Any malformation which is noticed at birth, whether it is the result of a genetic (inherited) or environmental cause.


Preserving substances at very low temperatures in vapour-phase or liquid nitrogen at 196 degrees centigrade. E.g.: frozen sperm, embryos, eggs, testicular tissue and ovarian tissue.

Culturing in vitro

Developing outside the body (i.e. in a Petri dish in the laboratory). Literal translation is ‘within the glass’.

Cumulative or fresh/frozen pregnancy rates

Pregnancy rates that are added up after all the eggs collected during the initial stimulated cycle have been used up, including those that were initially frozen.