Metabolism is the body's process of converting the food we eat and drink into the energy we need to think, move and grow. When a person drinks alcohol it passes from the stomach and intestines into the blood. The placenta links the blood suppy of the fetus to the blood supply of the mother and is essential to the growth of a healthy fetus. The placenta cannot keep harmful substances such as alcohol away from the fetus which is why we recommend that no alcohol in pregnancy is the safest option. Because the fetus metabolises alcohol more slowly than an adult does, the fetus's blood alcohol concentrations can be higher than the mothers.

Researchers use the term teratogen when referring to alcohol. A teratogen is a drug, chemical or even infection that interrupts or alters the normal development of a fetus, including development of the brain or other major organs. Other examples of teratogens include Rubella, radiation, mercury and thalidomide.

The possible effects of fetal alcohol exposure include:

• Brain damage
• Birth defects
• Poor growth
• Social and behavioural problems
• Delayed development
• Low IQ

Fetus or Foetus
The word 'fetus' is from Latin origins and meant offspring, bringing forth or hatching of young. Fetus is now the Standard English spelling throughout the world in medical journals. Where the alternate spelling of foetus is used in a published report, resource, website or journal article the spelling has not been changed.

Fetal development
Gestational age refers to the length of time since the first day of the last menstrual period.

Fetal age refers to the age of the developing baby, counting from the estimated date of conception. The fetal age is usually two weeks less than the gestational age.

The drawing below shows the critical times for the development of the organs such as the brain, heart, ears and eyes in the fetus. The weeks referred to in this image are the gestational age of the fetus. This graphical representation has been adapted from Little BB. 2007: Drugs and Pregnancy, A Handbook. London: Hodder Arnold.