Bma Illustrated Medical Dictionary

fetal alcohol syndromeA rare condi-

tion consisting of a combination of

congenitaldefects that result from the

continuous consumption of excessive

amounts of alcohol by the mother

throughout pregnancy. The affected

baby has diminished growth, delayed

mental development, a small head, a

small brain, and small eyes. He or she

may have a cleft palate, a small jaw,

heart defects, and joint abnormalities.

As a newborn, the baby sucks poorly,

sleeps badly, and is irritable as a result

of alcohol withdrawal. Almost one-fifth

of affected babies die during the first

few weeks of life; and many who survive

are, to some degree, mentally and

physically handicapped.

fetal circulationBlood circulation in

the fetus is different from the normal

circulation after birth (see circulatory

system). The fetus neither breathes nor

eats. Therefore, oxygen and nutrients

are obtained and waste products such

as carbon dioxide are removed via the

placenta. Fetal blood reaches the pla-

centa through blood vessels in the

umbilical cord. The maternal and fetal

circulations are separated by a thin

membrane in the placenta, which allows

the exchange of nutrients and waste

products. The other fundamental differ-

ence in circulation is that most blood

bypasses the lungs in the fetus through

2 special channels in the fetal heart.

Blood passes from the right atrium of

the heart to the left atrium through the

foramen ovale. Another channel, known

as the ductus arteriosus, allows blood

to pass from the pulmonary artery to

the aorta. Both channels normally close

after birth. In rare cases, they fail to

close, causing a congenital heart disor-

der (see heart disease, congenital).

fetal distressThe physical stress experi-

enced by a fetus during labour as a

result of its not receiving enough oxygen.

During a contraction, the uterus tight-

ens and reduces the oxygen supply from

the placenta to the fetus. If, in addition,

there are problems, such as pressure on

the umbilical cord or the mother’s los-

ing blood, there may be an inadequate

amount of oxygen reaching the fetus.

Fetal distress may cause the baby’s

heart-rate to slow or to fail to show nor-

mal variability, which can be recorded

on a cardiotocograph (see fetal heart

monitoring). Acidosis(high acidity in

the body), which can be detected in a

sample of blood taken from the scalp,

indicates that the oxygen supply to the

fetus is inadequate. Signs of meconium

in the amniotic fluid can also be an

indication of fetal distress.

Fetal distress sometimes occurs as a

temporary episode, but, if acidosis is

severe, the distressed fetus may need

to be delivered promptly by caesarean

section, forceps delivery, or vacuum

extraction. (See also childbirth.)

fetal heart monitoringThe use of an

instrument to record and/or listen to

an unborn baby’s heartbeat during

pregnancy and labour. Monitoring is

carried out at intervals throughout preg-

nancy if tests indicate that the placenta

is not functioning normally or if the

baby’s growth is slow. During labour,

monitoring can detect fetal distress, in

which oxygen deprivation causes abnor-

mality in the fetal heart-rate.

The simplest form of fetal heart moni-

toring involves the use of a special fetal

FETAL ALCOHOL SYNDROME FETAL HEART MONITORING

F

Umbilical
vein

Umbilical
arteries

Left

atrium

From upper To upper body
body

Right
atrium

Lung

Foramen
ovale

Ductus
venosus
(liver
bypass)

Aorta

Ductus

arteriosus

(lung

bypass)

Heart

To lower

body

Descending

aorta

FETAL CIRCULATION

Placenta

Pulmonary

artery