BIRTHING CHAIR
they may cause birth defects. For exam-
ple,
rubella
(German measles) in early
pregnancy can cause fetal abnormalities,
including deafness, cataract (clouding
of the lens of the eye), and heart dis-
ease.
Toxoplasmosis
(infection with a
parasite found in cats’ faeces), can also
be passed on to the fetus, causing dam-
age to the eyes, liver, and other organs.
OTHER COMMON DEFECTS
Abnormalities in the embryo’s develop-
ment can damage the brain and spinal
cord, causing defects such as spina bif-
ida and
hydrocephalus
(a buildup
of
fluid in the brain). In congenital heart
disorders (see
heart disease, congenital
),
there is a structural abnormality in the
heart that may interfere with normal
blood flow.
Cleft lip and palate
result
from a failure of the two sides of the
fetal face and palate to join completely
DETECTION
Ultrasound scanning
and blood tests dur-
ing pregnancy can identify women at
high risk of having a baby with a birth
defect. Further tests such as c
horionic vil-
lus sampling, amniocentesis,
or
fetoscopy
may then be carried out.
PREVENTION
Some birth defects can be prevented, or
the risks minimized; for example, by
rubella immunization before pregnancy
or avoiding teratogens during pregnancy.
birthing chair
A specially designed chair to support a
woman during
childbirth.
In the opinion
of many doctors, sitting, as opposed to
lying down, can help to shorten labour.
birth injury
Damage sustained by a baby during
childbirth.
Minor injuries, such as bruis-
ing and swelling of the scalp during a
vaginal delivery (see
cephalhaematoma)
are common. More serious injury can
occur, particularly if the baby is large
and has difficulty passing through the
birth canal. A
breech delivery
may result
in injury to nerves in the baby’s shoul-
der, causing temporary paralysis in the
arm. The face may be paralysed tempor-
arily if the facial nerve is traumatized by
forceps during delivery. Fractured bones
are another hazard of difficult deliveries,
but the bones usually heal easily. (See
also
birth defects; brain damage.)
birthmark
An area of discoloured skin that is
present at birth, or appears very soon
afterwards. Birthmarks include
moles,
freckles, and other types of melanocytic
naevi
(a variety of flat, brown to blue-
grey skin patches), strawberry marks
(bright red, usually protuberant areas),
and port-wine stains (purple-red, flat,
often large areas). The latter two are
types of
haemangioma
(malformation of
blood vessels). Strawberry marks often
increase in size in the first year, but most
disappear after the age of nine. Port-
wine stains seldom fade, but some of
them can be reduced by
laser treatment
during adulthood.
Birthmark
Strawberry marks, a common type of birthmark
caused by malformation of blood vessels, are
usually bright red, protuberant, and spongy.
birthpool
A pool of warm water in which a
woman can sit to help relieve pain dur-
ing labour (see
childbirth).
birth, premature
See
prematurity.
birth, preterm
See
preterm birth.
birth rate
A measurement of the number of births
in a particular year in relation to the size
of the population.
birthweight
A baby’s weight at birth, which usually
ranges from 2.5 to 4.5 kg. Birthweight
depends on a number of factors, includ-
ing the size and ethnic origin of the
parents. Baby boys weigh, on average,
slightly more than baby girls. Babies who
weigh less than 2.5 kg at birth are con-
sidered to be of low birthweight. Causes
include
prematurity
and undernourish-
ment in the uterus (because the mother
had
pre-eclampsia,
for example). Abnor-
mally high birthweight may be due to
unrecognized or poorly controlled
dia-
betes mellitus
in the mother.
bisacodyl
A type of stimulant
laxative drug
that
works by stimulating the intestinal wall
into contracting, increasing the speed at
which faecal matter passes through.
bisexuality
Sexual interest in members of both
sexes that may or may not involve sexual
activity.
bismuth
A metal, salts of which are used in
tablets to treat
peptic ulcer
and in creams
and suppositories to treat
haemorrhoids
(piles). Bismuth preparations taken by
mouth may colour the faeces black. The
tongue may darken and, occasionally,
nausea and vomiting may occur.
bisphosphonate drugs
Drugs used to slow bone metabolism
(for example, in
Paget's disease
) and to
reduce the high calcium levels in the
blood that are associated with destruc-
tion of bone by secondary cancerous
growths.
Bisphosphonate
drugs
may
also be used in the prevention or treat-
ment of
osteoporosis
.
bite
See
occlusion.
bites, animal
Any injury inflicted by the mouthparts
of an animal, which may range from
the puncture wounds of bloodsucking
insects to the massive injuries caused by
shark or crocodile attacks. Teeth, especi-
ally
those
of carnivores,
can
inflict
widespread mechanical injury. Severe
injuries and lacerations to major blood
vessels can lead to heavy blood loss and
physiological
shock.
Serious infection
may occur as a result of bacteria in the
animal’s mouth being transferred in the
bite, and
tetanus
is a particular hazard.
In countries where
rabies
is present, any
mammal may potentially harbour the
rabies virus and transmit it via a bite.
TREATMENT
Medical advice should be sought for all
but minor injuries, and in all cases if
there is a risk of rabies. The treatment
usually includes cleaning and examina-
tion of the wound. The wound will
usually be left open and dressed, rather
than stitched, as closing it can encourage
the multiplication of bacteria. Preventive
antibiotic drug
treatment and an anti-
tetanus injection may also be given.
Antirabies vaccine is given, together with
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