Antenatal care | Flashcards
What is the definition of gestation age?
Duration of pregnancy dated from the first day of the last menstrual period (LMP)
How many weeks gestation is the baby considered an:
- Embryo
- Fetus
- Embryo = fertilisation to 10 weeks gestation
2. Fetus = 10 weeks gestation to birth
Currently what is the median age of women giving birth in developed countries?
30 years
Why are the rates of pregnancy in the over 35 and 40 age group continue to rise (4)?
- Assess to assisted reproductive technologies has increased
- Social factors e.g. work
- Economic factors
- Education factors
What are the dates for the 3 trimesters of pregnancy?
Trimester 1 = week 0-13
Trimester 2 = week 14-27
Trimester 3 = week 28 onwards
How many weeks are:
- Full term
- Preterm
- Viability
- Full term = 37 weeks
- Preterm = <36 weeks
- Viability = >24 weeks
At how many weeks do women usually deliver?
38-42 weeks
What needs to be asked about concerning past obstetric history (10)?
- Gravidity - no. times a woman has been pregnant irrespective of outcome of pregnancy
- Any spontaneous miscarriages and induced abortions
- Complications during previous pregnancies
- Details of induction of labour
- Gestation at delivery
- Presentation and method of birth, assisted?
- Complications in the puerperium e.g. postpartum haemorrhage
- Birthweight of the baby, neonatal complications (need for special care baby unit) and long-term outcome
- Maternal physical and mental health during and after each pregnancy
- Breastfeeding history
Once a pregnancy has been confirmed, what should the doctor ask about in the history regarding complications or possible poor outcome of current pregnancy (8)?
.1. Whether pregnancy is wanted
- Symptoms of pregnancy or problems e.g. N+V/bleeding/pain
- Maternal and family history of hypertension, diabetes, mental health disorders and congenital and familial disorders
- Pre-pregnancy body weight, recent and past history of weight loss/gain and eating behaviour
- Cigarette smoking, caffeine intake, alcohol and other prescribed/social drug use
- Current and past history of physical and sexual abuse
- Family and community support
- Whether the woman has any concerns or worries about pregnancy.
Define gravidity
No. times a woman has been pregnant, irrespective of the outcome of the pregnancy e.g. termination/miscarriage, ectopic pregnancy
- What is primigravida?
2. What is multigravida?
- Pregnant for the first time
2. Pregnant on 2 or more occasions
What is parity?
Describes number of live-born children and stillbirths a woman has delivered after 24 weeks or with a birthweight of 500g
What are the 2 ways of calculating gestational age and pregnancy due date?
- Using LMP
2. Using ultrasound
How do you calculate the pregnancy due date using LMP?
- Ask the woman if the length of her menstrual cycle falls into the normal range (22-35 days)
- Add 1 year and 10 days to the first day of her LMP, then subtract 3 months
If a woman’s LMP began on 14th November 2010, what is her due date?
24th August 2011 (+/- 14 days)
How do you calculate gestational age?
Calculated from the first day of the mothers LMP
What 4 areas should be addressed regarding preconceptual care?
- Immunisation
- Dietary and vitamin supplementation
- Medications
- Advice on diet and exercise
In preconceptual care, what are women assessed for regarding immunisations?
The need for rubella, varicella and pertussis immunisation
What cautions need to be taken when giving immunisations to a woman who wants to get pregnant?
Vaccines for rubella, varicella and pertussis are live attenuated viral vaccines so the woman should defer contraception for 28 days after administration
What dietary and vitamin supplementation should a woman take preconceptually (3)?
- Folic acid supplement (400ug daily) for at least 1 month prior to conception and first 3 months of pregnancy
- Certain risk groups should take a higher dose (5mg daily) such as those on anti-epileptic agents, obese women, diabetic women or women with a past history of neural tube defects
- Iodine supplements is also recommended in countries where there is a dietary deficiency to aid in the development of the fetal brain
What is done regarding medications during preconceptual care?
It is reviewed and optimised
What should be considered when enquiring about family history in a woman who wants to get or is pregnant (2)?
- Most women will be aware of any significant family history of the common genetically based diseases
- They can be offered pre-natal diagnosis testing for women who would consider a termination of affected pregnancy when they are known to be a carrier of a recessively inherited genetic disorder and the father of the baby is known to be a carrier of the same disorder, or carrier status of the father is unknown and cannot be established
How do dominantly-inherited disorders translate clinically i.e. how likely is a child going to get the disease?
Only one parent needs to carry the mutation for the condition to be passed onto the child (50% chance)
What are 4 examples of genetic diseases that show a dominant-inheritance?
(nice to know)
- Neurofibromatosis - mutation in NF1 gene causing benign tumours to grow along nerves
- Tuberous sclerosis - mutation in TSC1 or 2 genes leading to benign tumours to grow in various parts of the body
- Huntington’s disease - mutation in HTT gene, causing progressive brain disorder with uncontrolled movements, emotional problems and loss of cognitive abilities
- Adult polycystic disease - Mutation in PKD1 or 2, causes cysts to develop in kidneys, affecting its function
How do recessively-inherited disorders translate clinically i.e. how likely is a child going to get the disease?
Condition is passed on if both parents have a copy of the faulty gene I.e. are carriers of the condition. If the child inherits one copy of the faulty gene, they are a carrier of the condition but won’t have it.
What are 2 common recessively-inherited disorders?
- Cystic fibrosis
2. Haemoglobinopathies e.g. sickle cell anaemia
What is the pathophysiology of CF? (2)
- Caused by mutation in CFTR gene which usually codes for Cl- channels. Cl- controls movement of water in tissues, necessary for the production of thin, freely-flowing mucus.
- Mutations lead to thick and sticky mucus that damages respiratory and digestive systems
What are the clinical features of CF? (6)
- Chronic coughing
- Wheezing
- Inflammation
- Mucus build up, leading to infection, which result in permanent lung damage and scarring
- Poor growth or weight gain
- Frequent greasy, bulky stools or difficulty with bowel movements
What is the pathophysiology of sickle cell anaemia?
Patients have inherited the abnormal gene Hb S which forms an abnormal beta-globin chain that causes it to polymerize when deoxygenated, which distorts the erythrocyte into a sickle shape.
How do X-linked disorders translate clinically i.e. how likely is a child going to get the disease?
Mutation on the X chromosome. Don’t affect females to a significant degree as they have 2 X chromosomes. Males can’t inherit X-linked mutations from their fathers because they receive a Y chromosome from them, so only gets the condition if he inherits from his mother. He cannot compensate as he only has 1 X chromosome
What are 3 examples of X-linked disorders?
nice to know
- Duchenne’s muscular dystrophy - mutation of the dystrophin gene at Xp21, causing worsening muscle weakness from the age of 4
- Fragile X syndrome - mutations in FMR1 gene causing developmental problems
- Haemophilia A and B - Reduced levels of factor VIII and IX respectively, causing abnormal clotting, leading to prolonged bleeding
Why is it difficult to assess the effects of substance use in pregnancy?
Illicit substance use is associated with drinking, and malnutrition as well
What are the 4 most common illicit substances taken during pregnancy?
- Heroin
- Cocaine
- Amphetamines
- Marijuana
What are the dangers of heroin use during pregnancy (4)?
Associated with increased risk of:
- IUGR
- Perinatal death
- Preterm labour
- 50% of infants will also suffer from neonatal withdrawal.
What are the dangers of amphetamine use during pregnancy (6)?
Associated with increased risk of:
- Miscarriage
- Preterm birth
- Growth restriction
- Placental abruption
- Fetal death in utero
- Developmental anomalies
What are the dangers of marijuana use during pregnancy?
No apparent adverse effect
What are the dangers of cocaine use during pregnancy?
- Mother (6)
- Fetus (4)
Mother:
- Can induce cardiac arrhythmias in mother
- Can induce CNS damage in mothers
- Uterine rupture
- Hypertension
- Seizures
- Death
Fetus:
- Placental abruption
- IUGR
- Preterm labour
- Congenital abnormalities
What are the dangers of alcohol intake during pregnancy (5)?
Fetal alcohol syndrome - leads to:
- Facial abnormalities
- CNS dysfunction (microcephaly, mental retardation)
- Growth retardation
- Cardiac defects
- Multiple joint anomalies
What are the dangers of smoking during pregnancy (5)?
- Decreased fertility
- Increased spontaneous abortion
- Preterm birth
- Perinatal mortality
- Low birth weight infants
What are the dangers of neonatal exposure to cigarette smoke (4)?
Associated with:
- Sudden infant death syndrome
- Asthma
- Respiratory infections
- Attention deficit disorder
What are the risks of drug treatment in pregnancy?
What are the changes in pregnancy that alters the way drug absorption occurs?
(4)
- Volume of distribution changes in pregnancy - plasma volume rises and total body water increases. This would be expected to decrease drug levels, but albumin concentrations decline so protein binding of many drugs is lower in pregnancy leading to an increase in circulating free/active drug levels
- Metabolism and elimination are also altered in pregnancy. High steroid hormone levels affect hepatic metabolism and prolong the half-life of some drugs. Glomerular filtration rates rise, increasing the renal clearance of some drugs.
- Teratogenicity of some drugs.
- Drug absorption is altered in pregnancy. Gastric emptying and gastric acid secretion are reduced.
What affects the rate of drug transfer across the placenta from the mother to the fetus?
Governed by the solubility of the ionised molecules in fat and the thickness of the trophoblast.
What drugs cross the placenta to the fetus?
What drugs don’t?
With the exception of large molecules (I.e. heparin), all drugs given to the mother cross the placenta to some degree.
How does the rate of drug transfer passing from mother to fetus change in 2nd half of pregnancy?
The trophoblast becomes thinner, whereas the placental area increases in size; drugs therefore pass through more rapidly.
During which period of time is the biggest risk of teratogenicity of a drug to the fetus?
During organogenesis i.e. 17-70 days post-conception
After this, the risk of major birth defects is almost negligible
What are 5 drug prescribing principles for pregnant women?
- Only use medications if absolutely indicated
- If possible, avoid initiating therapy during the first trimester
- Use lowest effective dose
- Single-agent therapy is preferable
- Select safe medication
How many routine antenatal appointments do non-complicated parous women have vs non-complicated multiparous women?
Parous = 10
Multiparous = 7
At how many weeks do pregnant women have their antenatal screening appointments throughout their pregnancy and briefly mention what that appointment is for?
*the extra appointments only for parous women
By 10 weeks = booking appointment
16 weeks = Standard screen
18-20 weeks = Anomaly scan if she chooses. (Another one can be offered at 32 weeks if placenta extends across the internal cervical os)
*25 weeks = Standard screen
28 weeks = Standard screen - Offer 2nd screening for anaemia and atypical red-cell alloantibodies
- Offer anti‑D prophylaxis to rhesus‑negative women
- Investigate a haemoglobin level below 10.5 g/100 ml and consider iron supplementation, if indicated
- 31 weeks = Standard screen
- Review and discuss results of screening tests from previous appointment
34 weeks = Standard screen
- Discuss preparation for labour and birth, including information about coping with pain in labour and the birth plan. Discuss recognition of active labour
- Offer a 2nd dose of anti-D to Rhesus-negative women
- Review, discuss and record the results of screening tests undertaken at 28 weeks
36 weeks = Standard screen
- Check lie and presentation of baby (Offer ECV if breech)
- Discuss with the mother:
1. Breast feeding technique and good management practises
2. Care of the new baby
3. Vit K prophylaxis and new born screening tests
4. Postnatal self-care
5. Awareness of “baby blues” and post-natal depression
38 weeks = Standard screen
-Give info on options for management of prolonged pregnancy, with opportunity to discuss issues and ask qs
- 40 weeks = Standard screen
- Give info on options for management of prolonged pregnancy, with opportunity to discuss issues and ask qs
41 weeks = Standard screen
- A membrane sweep should be offered
- Induction of labour should be offered
What 3 standard screening tests are done at every antenatal visit?
- Blood pressure
- Urine dip for proteinuria
- Symphysis-fundal height
What are the general points that should be considered at each antenatal routine screening appointment? (4)
- Healthcare providers should remain alert to risk factors, signs or symptoms of conditions that may affect the health of the mother and baby, such as domestic violence, pre-eclampsia and diabetes
- Give information, with an opportunity to discuss issues and ask questions at every appointment
- Ask if mother has been feeling fetal movements
- Once the fundus of the uterus can be palpated abdominally, the fetal heart can be detected with a hand held Doppler at each visit
At the booking appointments by 10 weeks, what topics needs to be discussed (9)?
- How the baby develops during pregnancy
- Nutrition and diet, including vitamin D supplementation
- Exercise, including pelvic floor exercises
- Antenatal screening, including risks and benefits of the screening tests
- Pregnancy care pathway
- Place of birth
- Breastfeeding, including workshops
- Participant‑led antenatal classes
- Maternity benefits
At the booking appointments by 10 weeks, what screening is done? (5)
- Weight and height -> BMI
- Hx to ask about physical or mental illnesses incase further assessment or care is necessary
- USS offered between 10 weeks-13 weeks 6 days to determine gestational age and screen for Down’s syndrome.
- Blood tests
- Checking blood group, rhesus D status and screening for haemoglobinopathies, anaemia, red‑cell alloantibodies, hepatitis B virus, HIV, rubella susceptibility and syphilis - Urine tests
- proteinuria and screen for asymptomatic bacteriuria
What do blood tests that done at the booking appointment check for (9)?
- Blood group
- Rhesus D status
- Screening for haemoglobinopathies
- Anaemia
- Red‑cell alloantibodies
- Hepatitis B virus
- HIV
- Rubella susceptibility
- Syphilis
What do urine tests done at the booking appointment check for (2)?
- Proteinuria
2. Asymptomatic bacteriuria
What are some indications for USS in pregnancy?
0-10 weeks: Scan if doubt about gestational age
11-13 weeks: Scan for nuchal fold thickness for trisomy 21, 13 and 18
18-20 weeks: Fetal anomaly scan
21-30 weeks: Detection of multiple pregnancy, fetal death, antepartum, haemorrhage, clinical polyhydramnios
31-40 weeks: Assessing fetal growth, maternal disorders e.g pre-eclampsia, antepartum haemorrhage etc
What are the 3 limitations of using USS in pregnancy?
Degree of success is influenced by:
- Maternal habitus
- The skill of the operator
- The size of the anomaly
What are the 5 techniques for fetal monitoring?
- Cardiotocography (CTG)
- Fetal movements
- Biophysical profile
- Serial US examinations
- Fetal blood flow velocity
What are the goals of fetal monitoring (2)?
- Early identification of a fetus at risk for preventable morbidity or mortality due specifically to uteroplacental insufficiency
- Detection of progressive fetal asphyxia which can lead to fetal death or handicap
What does CTG measure?
Fetal heart rate pattern with time
What is the mneumonic for reading a CTG?
DR. = determined risk e.g. preterm labour/decreased fetal movement? C. = contractions/Braxton Hicks BR = base rate. Normal is 110-160 beats/min V = variability. Normal is >5 bpm (jagged line). A = acceleration. Normal is >15 beats in 15 secs D = deceleration, drops in heart rate from baseline O = Overall
What is the normal heart rate for a fetus?
110-160 beats/min
When does a mother usually start to feel fetal movements?
2nd half of pregnancy
At term, how often does a fetus move on average?
31 times per hour with a range of 16-45 with the longest interval between movements 50-75 mins
How long is it ok for fetal movements to be absent during sleep cycles?
20-40 mins, rarely exceeding 90 mins
What would you advise a woman who does not feel her fetus moving?
She should lie on her left side and contact her maternity care giver immediately if they do not feel 10 contractions in the next 2 hours.
What is the biophysical profile of a fetus?
What variables is it made up of? (5)
Sonographic scoring system designed to assess fetal well-being.
Five variables:
- CTG
- Fetal movement
- Fetal tone
- Amniotic fluid volume
- Fetal breathing.
How is the biophysical profile of a fetus scored?
2 points awarded if variable is present or normal, 0 if absent or abnormal
A normal score is 8-10, lower than a score of 6, suspect asphyxia.
What are disadvantages of a biophysical profile of a fetus?
Time-consuming, and no evidence to suggest it is better than CTG and Doppler blood-flow testing
At what intervals can a fetus be monitored with serial USS at?
3 weekly intervals
What 3 parameters are measured in serial US examinations of the fetus?
- Abdominal circumference
- Head circumference
- Femur length
Plotted on a centile chart
How does fetal blood flow velocity work? (3)
- Umbilical artery Doppler velocimetry measurements reflect resistance to blood flow from the fetus to the placenta
- Absent or reversed diastolic flow is associated with poor perinatal outcome in the setting of IUGR and urgent delivery should be considered.
- Abnormal flow in the middle cerebral artery and ductus venosis can help in the timing of delivery of IUGR fetuses.
In antenatal screening for genetic abnormalities, which 3 syndromes are they screening for?
Trisomy 21, 13 and 18
What are the 3 antenatal screening regimens offered for detection of genetic abnormalities?
- Measurement of pregnancy-associated plasma protein A and free beta-human chorionic gonadotrophin (beta-hCG) levels at 9-13 weeks gestation. In Down’s, PAPP-A may be low and beta-hCG may be raised.
- Nuchal thickness of the fetus between 10 weeks and 13 weeks 6 days on USS is compared with maternal age. Increased thickness can indicate oedema due to heart failure, suggesting Down syndrome.
- Combines levels of beta-hCG, alpha-fetoprotein (AFP), free unconjugated oestriol and inhibin A (in some centres), measured between 15-20 weeks. Oestriol and AFP levels are lower in Down’s and beta-hCG are raised.
If there is a higher risk of Down’s syndrome (>1/200 to 1/250), what 2 diagnostic tests can be done to confirm it and at what gestation?
- Chorionic villus sampling (CVS) at gestation 11-14 weeks
2. Amniocentesis from 15 weeks gestation
How does CVS work?
A sample of chorionic tissue is removed from the placental edge by aspiration via a needle transabdominally with US guidance.
A karyotype is then made within 24-48 hours.
How does amniocentesis work?
The needle is pushed through the abdominal wall and into the amniotic sac, guided by US, and a sample of amniotic fluid is removed. The fetal cells obtained are cultured and harvested, and a karyotype is made of the chromosomes in 2 weeks.
What is the advantage of CVS over amniocentesis and a limitation?
CVS is quicker than amniocentesis but less accurate
When does screening for open neural tube defects occur antenatally?
During screening for Downs and the use of 2nd trimester USS
How does Rhesus disease occur? What antibodies are involved?
3
- Occurs when a Rh-negative woman is exposed to Rh-positive blood from their fetus, producing an antibody response
- The initial immune response is IgM, which does not cross the placenta so the index pregnancy is not affected.
- Following sensitisation after birth, subsequent pregnancies will trigger an IgG response which will cross the placenta and cause haemolysis
What is given to prevent Rhesus disease?
Passive immunisation 72 hours before exposure with anti-D IgG can destroy fetal erythrocytes in maternal circulation before it evokes a maternal immune response.
What is important with regards to the timing of passive immunisation to prevent Rhesus disease? (5)
It needs to be given at the right time:
- Threatened/spontaneous miscarriage
- Invasive procedures
- Routinely antenatally at 28 and 34 weeks gestation
- Routinely at delivery if infant is Rh D positive
- It should be administered as close to the sensitising event as possible and within 72 hours.
What is important with regards to the amount of passive immunisation to prevent Rhesus disease?
It must be sufficient to remove all fetal cells from the maternal circulation
What test can be done to check if enough passive immunisation has been given to prevent Rhesus disease?
The Kleihauer-Betke test identifies fetal cells in maternal blood, so can be used to determine the volume of FMH and to assess whether additional doses of anti-D are required.
What is the WHO definition of an antepartum haemorrhage?
A significant bleed from the birth canal occurring after the 24th week of pregnancy
What are 3 causes of antepartum haemorrhage from the vagina?
- Haemorrhage from the placental site and uterus:
- Placenta praevia
- Placenta accreta
- Placenta abruption - Lesions of the lower tract
- heavy show/onset of labour
- cervical ectropion/carcinoma
- polyps
- vulval varices
- trauma
- infection - Bleeding from fetal vessels including vasa praevia
What is the mechanism of placenta praevia and how does it cause bleeding? (2)
- The placenta is implanted either partially or wholly in the lower uterine segment and lies below (praevia) the fetal presenting part.
- The bleeding occurs when the lower uterine segment increases in length and shearing forces between the trophoblast and maternal blood sinuses occur.
At what gestation does the first episode of bleeding occur with placenta praevia?
Usually occurs after the 36th gestational week
What are risk factors for placental praevia (3)?
Risk increases with:
- Multiparity
- With each C-section
- Multiple pregnancy
What are the features of bleeding due to placenta praevia (4)?
What are 2 other common clinical features?
Bleeding is:
- Painless
- Causeless
- Recurrent
- Unpredictable - usually first bleed is mild but can vary to being massive and life-endangering
Malpresentation of fetus
Normal uterine tone
How is placenta praevia diagnosed?
By USS
- at 18 weeks a low-lying placenta may be identified. Vaginal delivery may still be possible as the lower uterine segment does not develop fully until late in 3rd trimester
- Repeat USS at 32nd week or earlier if bleeding occurs
What is the management of mild-moderate bleeding due to placenta praevia (5)?
- On first episode of bleeding, bleeding is usually mild-moderate, but admit to hospital. Do not VE
- Check patients vital signs, amount of blood loss
- Cross-match blood in case transfusion needed
- USS to confirm diagnosis
- CTG to determine fetal status