| amnion | the fluid-filled membrane enclosing the baby in the womb. |
| ante-natal | before birth. |
| blastocyst (Greek, "sprout pouch') | the hollow, fluid-filled ball of cells which is the developing embryo at one week after fertilisation. |
| cervix | neck of the womb. |
| chorion | the outer capsule containing amnion, fluid and baby within the womb. |
| chromosome | part of a cell nucleus, made of DNA, carrying the genes; each species of animal and plant has a characteristic number of chromosomes per cell, except in reproductive cells which have only half that number to allow for their combination at fertilisation. |
| differentiation | development of cells to perform specialised functions (making nerves, bones, organs etc.). |
| DNA (deoxyribonucleic acid) | threadlike molecule in the nucleus of a living cell which can reproduce itself and transmit hereditary characteristics. |
| EEG (electroencephalograph) | an instrument which detects and records brain activity. |
| embryo (Greek, "to teem within") | stage of human development during the first eight weeks after fertilisation. |
| fallopian tubes | two tubes, one on each side of the womb, connecting it with the ovaries; fertilisation normally takes place in one of the Fallopian tubes. |
| fertilisation
| the joining of sperm with ovum, completed when their nuclei are combined, to make a genetically new individual. |
| foetus (Latin, 'young, offspring') | the developing human from eight weeks after fertilisation up to birth. |
| fraternal twins | twins who do not look alike because they develop from two different eggs and sperm cells. |
| full-time delivery | birth of a baby after a completed nine-month pregnancy (i.e. not a premature birth). |
| fundus | the top part of the womb, lying between the Fallopian tubes, which expands upwards as pregnancy advances and enables the doctor to assess the length of pregnancy. |
| gamete (Greek, "marriage partner") | reproductive cell; egg or sperm. |
| gene | a factor controlling inheritance of one particular characteristic (e.g. brown eyes). |
| gestational age | the baby's age calculated by estimating pregnancy as starting from the first day of the mother's last menstrual period. |
| hormone | substance produced by an organ or a gland which influences other organs or the whole body. |
| homo sapiens (Latin, "thinking man") | the human species. |
| identical twins | twins who look alike because they result from one egg and sperm when the zygote splits into two separately developing cells. |
| labour | the process of expelling baby, membranes and placenta from the womb. |
| morula (Latin, "mulberry") | the earliest stage of human embryo development; the first four days of life when the growing cell cluster looks like (but is not) a berry. |
| ovary | the egg-producing organ; normally a woman has two ovaries which take turns to release one egg per month. |
| ovum | egg (plural ova). |
| placenta | a temporary organ within the uterus which transfers nourishment and oxygen from the mother, removes waste products from the baby, and makes hormones to maintain and end pregnancy. Expelled after the baby is born, it is then also known as the "afterbirth". |
| post-natal | after birth. |
| prematurity | the baby is born before 37 completed weeks since the mothers last period and needs special care. |
| sentient capacity | the ability to feel sensations such as pain. |
| stillbirth | the baby is born dead. |
| trimester | a three month period of pregnancy. The first trimester covers the first to the third months; the second trimester the fourth to the sixth months; and the third trimester the seventh to the ninth months. |
| ultrasound | a technique for viewing the unborn child: high-frequency sound waves directed through the mothers abdomen send back signals which are converted to images on a screen. |
| umbilical cord | a temporary lifeline connecting the unborn child with the placenta, channelling nourishment from the mother and removing wastes from the baby. |
| uterus | the womb; in utero (Latin) in the womb. |
| vagina | the birth canal. |
| vernix | a greasy coating protecting the unborn baby's skin from prolonged contact with the fluid in the amnion. |
| zygote (Greek, 'joining') | the new, one-celled being formed when sperm fertilises egg; the zygote of the species Homo sapiens is a human being at the earliest stage of life. |