Foetal growth Flashcards
Define foetal growth
The increase in mass that occurs between the end of the embryonic period and birth.
(i.e. not development of structurs)
What is Symphysis Fundal Height (SPH)
the distance between the pubic symphysis and the top of the uterus, as shown in Figure 6.1
What might lead to lower values for the SFH at each week of development than should be the case
wrong last menstrual period date,
the baby in a transverse lie,
or complications including oligohydramnios (low levels of amniotic fluid)
or a baby that is small for gestational age (SGA).
Why might higher values be found for SFH than should be
wrong last menstrual period date,
multiple pregnancy,
or
maternal obesity.
Complications:
molar pregnancy, fibroids, polyhydramnios or a baby that is large for gestational age (LGA).
What can SFH detect
This simple and inexpensive measurement may identify gross changes in size, and hence gross complications in the pregnancy,
Why is SFH of limited use
many confounders, which include the problems listed above, as well as considerable inter-operator variability.
Why might the size of foestuses during miscarriage of pregnacy not be the best representation of normal foetal size at that age
did not take account of the possible causative relationship between low fetal growth leading to miscarriage, and hence such data may be inaccurate.
Differentiate changes in foetal height and foetal weight in pregnancy
It can be seen that fetal weight continues to increase during pregnancy, while fetal length changes less in the later stages.
Measure of length of foetus
Crown rump length
What was miscarriage data for foetal growth replaced with
in utero scanning
When is foetal growth fastest
Mid-third trimester
What is responsible for extent of foetal growth
- Genetic
2. Substrate supply
Outline the genetics as responsible for extent of foetal growth
- derived from both parents
- parents who are taller or bigger will have infants that are different in size to parents who are shorter or lighter in build.
- mediated by factors under genetic control, including mediators such as the insulin-like growth factors.
Outline the substrate supply as responsible for extent of foetal growth
sufficient nutrients are essential to achieve genetic potential. This is primarily based on the placenta which is dependent upon both uterine and placental vascularity.
How is foetal growth assessed on ultrasound
Biparietal diameter (BPD),
Head Circumference (HC),
Abdominal Circumference (AC)
and
Femur Length (FL).
What is a composite measure of growth from ultrasound, what is it based on
Estimated Fetal Weight (EFW):
based on
Biparietal diameter (BPD),
Head Circumference (HC),
Abdominal Circumference (AC)
and
Femur Length (FL).
What can normative growth curves from ultrasound measurements be used for
They are used clinically to identify a normal intrauterine growth and detect risk of obstetric and neonatal complications.
What is ultrasound most importnat for
Note that ultrasound can also be used to assess fetal wellbeing, which can be a more important use of the technology
Why are centiles important and useful
allows compensation for different sizes of infants that are growing and developing normally.
How should the growth pattern for each of the 4 US variables look over time
For any infant, the changes in each parameter can be plotted, and the growth over time visualised. In a normal pregnancy, each parameter is expected to follow a centile, showing steady increases in size.
What are customised foetal growth charts
- allow for a more individualised assessment
- based on fetal weight curves for NORMAL pregnancies
- adjusted to reflect maternal constitutional variation e.g. maternal height, weight, ethnicity, parity.
- optimised by presenting a standard free from pathological factors such as diabetes and smoking.
What is growth velocity, and state patterns
Overall average rate at which an infant gains weight
14-15 weeks= 5g/day
20 weeks= 10g/day
32-34 weeks=30-35g/day
AFTER 34 WEEKS DECREASES: decreased velocity towards the end of pregnancy
GROWTH RATE HIGHEST MID-THIRD TRIMESTER
What are the 3 phases of foetal growth
Cellular hyperplasia (increased cell numbers): 4-20 weeks
Hyperplasia and hypertrophy (increased cell size): 20-28 weeks
Hypertrophy dominates: 28-40 weeks
Is hyperplasia or hypertrophy more important for foetal weight gain? How do we know
As the main increase in fetal weight occurs during the final trimester of pregnancy, hypertrophy is a key factor.
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What is last menstrual period an estmate of
Gestational age (i.e. PF plus around two weeks)
What are the confonding factors around LMP
Irregular length of periods; abnormal endometrial bleeding; the use of oral contraceptives; breastfeeding.
When is LMP less liley ot be precise
If couple weren’t planning pregnancy
Why is dating in pregnancy importnat
a change in the dates may lead to a pregnancy being inappropriately identified as Large or Small for gestational age
Clinical decisions about delivery timings and methods (induction or Caesarean section) may not be correct
glucocorticoids are given prior to preterm delivery to enhance lung surfactant production and subsequent lung function.
All pregnancies dated by CRL apart from IVF
HC used if scan done after 14wk
Ho can the pregnancy be dated by US, at what time and why
determining the Crown-Rump length of the fetus, preferably towards the end of the first trimester; variations in fetal size are more limited at this stage of development, so the gestational age of the infant can be estimated more precisely.
Maternal factos affecting foetal growth
- Poverty
- Mother’s age
- Drug use
- Alcohol
- Smoking and nicotine
- Diseases
- Mother’s diet and physical health
- Mother’s prenatal depression
- Environmental toxin
How can poverty affect foetal growth
- more likely to have children at a younger age, which can result in low birth weight
- Many of these expecting mothers have little education and are therefore less aware of the risks of smoking, alcohol, and drugs – other factors that influence the growth rate of a fetus.
- Women in poverty are more likely to have diseases that are harmful to the fetus.
How can mother age affect foetal growth
- Women over 35 are more inclined to have a longer labour period, could result in death of mother or fetus.
- Women under 16 and over 35 have higher risk of preterm labour and this risk increases for women in poverty, African Americans, and women who smoke
- Young mothers more likely to drink, smoke, drugs
- Premature babies from young mothers increase likelihood of neuro defects influencing their coping
- increased risk of Down syndrome for infants born to those aged over 40 years
- Young teenaged mothers (younger than 16), and mothers over 35, are more exposed to the risks of miscarriages, premature births, and birth defects.
How do drugs reach the foetus
Maternal drug use occurs when drugs ingested by the pregnant woman are metabolized in the placenta and then transmitted to the fetus
What can maternal drug use lead to
- greater risk of birth defects, low birth weight, and a higher rate of death in infants or stillbirths.
- extreme irritability, crying, and risk for SIDS once the fetus is born
Effect of marijuana on foetal groth
Marijuana will slow the fetal growth rate and can result in premature delivery. It can also lead to low birth weight, a shortened gestational period and complications in delivery
Effect of heroin on foetal growth
interrupted fetal development, stillbirths, and can lead to numerous birth defects. Heroin can also result in premature delivery, creates a higher risk of miscarriages, result in facial abnormalities and head size, and create gastrointestinal abnormalities in the fetus. There is an increased risk for SIDS, dysfunction in the central nervous system, and neurological dysfunctions including tremors, sleep problems, and seizures. The fetus is also put at a great risk for low birth weight and respiratory problems.
Effect of cocain on foetal weight
maller brain, which results in learning disabilities for the fetus. Cocaine puts the fetus at a higher risk of being stillborn or premature. Cocaine use also results in low birthweight, damage to the central nervous system, and motor dysfunction.
Effect of alcohol on foetal growth
disruptions of the fetus’s brain development, interferes with the fetus’s cell development and organization, and affects the maturation of the central nervous system
What organs can alcohol use affect in foetus
heart and other major organ defects, such as small brain
What can result from brain defects due to alcohol use in pregnancy
Could affect the fetus’s learning behaviors. Alcohol use during pregnancy can cause behavioral problems in a child,
How can alcohol affect the foetus when it is a child
lcohol use during pregnancy can cause behavioral problems in a child, mental problems or retardation and facial abnormalities – meaning smaller eyes, thin upper lip, and little groove between the nose and lips.
T/F alcohol can also increase the risk of miscarriages and stillbirths, or low birth weight.
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What is foetal alcohl sndrome
Children with FAS have a variety of distinctive facial features, brain abnormalities, and cognitive deficits.
How can smoking affect foetal growth
fetus is exposed to nicotine, tar, and carbon monoxide.
How does nicotine and CO affect foetus
Nicotine results in less blood flow to the fetus because it constricts the blood vessels
Carbon monoxide reduces the oxygen flow to the fetus.
Eduction of blood and oxygen flow results in stillbirth, low birth weight, and ectopic pregnancy. There is an increase of risk of sudden death syndrome (SIDS) in infants.
What can increase ris of asthma for baby
smoking during pregnancy
ow birth weight and premature births can also increase the risk of asthma if a mother smoked during pregnancy because of the effects on the respiratory system of the fetus.