Fetal Growth and Growth Abnormalities
What are fetal growth and fetal abnormalities?
- During the fetal stage, fetal growth may be
inhibited or increased for various reasons. The
growth deviation is assessed as weight in relation
to the weight that one expects based on the length
of pregnancy. The weight is calculated on the basis
of measurements at ultrasound.
- SF measure (symphys-fundus measure):
- A more common, but more unspecific, method
of calculating growth deviation is to measure
the distance from the pubic bone (symphysis) to
the upper edge of the uterus (fundus)
- The SF measure is routinely measured at each
maternity check in the midwife after pregnancy
week 24. If the measurements show poor or
remarkably high growth, the pregnant woman will
be referred for an ultrasound examination.
What counts as normal birth weight?
- The average weight for live born Swedish
children is about 3500 grams. WHO has the following
definitions for birth weight:
- High: over 4500 g
- Normal: 2500-4500 g
- Low: less than 2500 g
- Very low: below 1500 g
- Extremely low: below 1000 g
- Fetal growth inhibition occurs in 3-10% of all
- Excessive SF measurements may be due to twins,
incorrect dating, large fetus or excessive amniotic
- Too low a SF measure may be due to incorrect
dating, small fetus or little amniotic fluid
- Planar SF curve may be due to cessation of fetal
growth (growth retardation). Visit Bestaah
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- An SF curve that rises too fast may be due to
increasing amniotic fluid (polyhydramnion).
- Large children:
- Children who weigh more than 4,500 g are at
increased risk of injury during childbirth.
Oxygen deficiency, lung damage, bone fracture or
nerve damage are more frequent
- Mothers who give birth to big children risk
increased bleeding and tissue damage in
connection with childbirth
- Small children:
- If the fetus grows smaller than normal, the
risk of complications in the child increases
during pregnancy and childbirth. It is therefore
important to identify these fetuses for close
monitoring and optimal timing of childbirth
What could be the cause?
Common causes of high SF dimensions:
- Hereditary cause of having big children
- Type 1 diabetes:
- Mothers with poorly regulated diabetes
mellitus can have big children with increased
fat deposits under the skin, fluid retention in
the body, unstable blood sugar, breathing
problems and brain bleeding
- Obesity in the mother:
- Increases the probability of a high birth
weight in the child. Obesity and obesity, BMI>
30 also lead to increased deformities,
especially in the child's nervous system. It
also involves increased risk of intrauterine
fetal death and neonatal mortality
- Twin pregnancy:
- The SF curve starts to rise steeper than the
normal curve around pregnancy week 20
- During routine ultrasound in pregnancy week
16-20 that most women undergo, twin pregnancies
More rare causes of high SF dimensions:
- Increased amniotic fluid (polyhydramnios):
- The causes may be malformations of the
central nervous system, malformations of the
gastrointestinal tract, multiple malformations
(heart failure, renal cyst), changes in the
placenta, disease of the mother or fetus, but in
some cases no cause can be detected
- Provides increased risk of premature
delivery, risk of umbilical cord complications
during water discharge. The mother often suffers
from the distended abdomen and shortness of
Common causes of low SF dimensions
- Many newborns who are small for their age
are small due to hereditary factors. The
mother's own birth weight and the siblings'
birth weight give a good indication of the new
baby's growth and weight
- Hereditary diseases, chromosome changes and
- Is a common cause of low birth weight and is
due to impaired placenta function
- Disease of the mother:
- Up to 10% of low birth weight is due to
infections such as symptom-free urinary tract
infection, rubella, cytomegalovirus infection,
toxoplasmosis or parvovirus infection
- Other diseases such as cystic fibrosis,
diabetes mellitus (type 1 and type 2), Crohn's
disease, ulcerative colitis, systemic lupus
erythematosus (SLE), cardiovascular disease and
kidney disease can also cause fetal growth.
- Smoking or use of drugs in the mother:
- May cause growth retardation in the child
- Mother's nutritional status:
- May have significance in severe eating
- Twins have lower birth weight. After
pregnancy week 30-32, growth begins to level off
Rare causes of low SF dimensions
- Too little amniotic fluid (oligohydramnion):
- Causes may be renal malformations,
circulatory failure of growth inhibited fetus,
which results in decreased urine output or
premature discharge of water
- The consequences of too little amniotic
fluid for the fetus may be poorer lung
maturation and malformations of the
musculoskeletal system. This is especially true
in case of premature water discharge early in
pregnancy before week 20
What can you do yourself?
- In most cases with abnormalities in the growth
of the fetus, there is not much you can do yourself,
but if you smoke or drink alcohol you should
definitely stop it.
- Healthy eating and plenty of exercise are always
The case history
- Acute illnesses during pregnancy?
- Chronic Diseases?
- Eating habits?
- Use of smoking, alcohol and drugs?
- Previous pregnancies? Former children's growth
- Hereditary diseases in the family?
- Usually the general health of the pregnant woman
is assessed, blood pressure is measured, SF
measurements are measured, weight is measured and
the fetal heart sounds are listened to.
- Other studies are a urine test to assess the
presence of glucose and / or protein. A urinary
culture is ordered in case of suspected urinary
- Possibly take simple blood tests such as blood
value, blood glucose value or infection samples.
- In case of suspicion of growth deviation - too
high or too low SF measures - the pregnant woman
will be referred for an ultrasound examination.
- In case of suspected growth inhibition, repeated
ultrasound examinations may give a more accurate
assessment of the fetal condition.
- It is usually the maternal care and
obstetricians (gynecologists) who assess the