Pregnancy

Question 1

Definitions

Answer 1

Last menstrual period (LMP) refers to the date of the first day of the most recent menstrual period

Gestational age (GA) refers to the duration of the pregnancy starting from the date of the last menstrual period

Estimated date of delivery (EDD) refers to the estimated date of delivery (40 weeks gestation)

Gravida (G) is the total number of pregnancies a woman has had

Primigravida refers to a patient that is pregnant for the first time

Multigravida refers to a patient that is pregnant for at least the second time

Para (P) refers to the number of times the woman has given birth after 24 weeks gestation, regardless of whether the fetus was alive or stillborn

Nulliparous (“nullip”) refers to a patient that has never given birth after 24 weeks gestation

Primiparous technically refers to a patient that has given birth after 24 weeks gestation once before (see below)

Multiparous (“multip”) refers to a patient that has given birth after 24 weeks gestation two or more times
TOM TIP: The term primiparous, or “primip” is a bit confusing. Technically, it refers to a woman that has given birth once before. However, it is often used on the labour ward to refer to a woman that is due to give birth for the first time (and has never given birth before). You may hear patients referred to on the labour ward as a “primip” when they have never given birth before.

The timeline for each pregnancy depends on the start date of the last menstrual period (LMP). This determines the gestational age (GA) and the estimated date of delivery (EDD) of the pregnancy. After the booking scan, the gestational age is more accurately assessed and the estimated date of delivery is updated accordingly.

The gestational age is described in weeks and days. For example:

5 + 0 refers to 5 weeks gestational age (since the LMP)
13 + 6 refers to 13 weeks and 6 days gestational age

Question 2

Gravidy and Parity

Answer 2

It is worth becoming familiar with gravida and para, as you will find this written on medical records. Here are some examples:

A pregnant woman with three previous deliveries at term: G4 P3
A non-pregnant woman with a previous birth of healthy twins: G1 P1
A non-pregnant woman with a previous miscarriage: G1 P0 + 1
A non-pregnant woman with a previous stillbirth (after 24 weeks gestation): G1 P1

Question 3

Trimesters

Answer 3

The first trimester is from the start of pregnancy until 12 weeks gestation.

The second trimester is from 13 weeks until 26 weeks gestation.

The third trimester is from 27 weeks gestation until birth.

It is worth noting that fetal movements start from around 20 weeks gestation, and continue until birth.

Question 4

Scans

Answer 4

Before 10 weeks Booking clinic Offer a baseline assessment and plan the pregnancy

Between 10 and 13 + 6: Dating scan

An accurate gestational age is calculated from the crown rump length (CRL), and multiple pregnancies are identified

16 weeks: Antenatal appointment

Discuss results and plan future appointments

Between 18 and 20 + 6: Anomaly scan

An ultrasound to identify any anomalies, such as heart conditions

25, 28, 31, 34, 36, 38, 40, 41 and 42 weeks

Antenatal appointments

Monitor the pregnancy and discuss future plans

Question 5

Additional Milestones

Answer 5

Additional appointments for higher risk or complicated pregnancies
Oral glucose tolerance test in women at risk of gestational diabetes (between 24 – 28 weeks)
Anti-D injections in rhesus negative women (at 28 and 34 weeks)
Ultrasound scan at 32 weeks for women with placenta praevia on the anomaly scan
Serial growth scans are offered to women at increased risk of fetal growth restriction

Question 6

Pregnancy Lifestyle

Answer 6

Take folic acid 400mcg from before pregnancy to 12 weeks (reduces neural tube defects)
Take vitamin D supplement (10 mcg or 400 IU daily)
Avoid vitamin A supplements and eating liver or pate (vitamin A is teratogenic at high doses)
Don’t drink alcohol when pregnant (risk of fetal alcohol syndrome)
Don’t smoke (smoking has a long list of complications, see below)
Avoid unpasteurised dairy or blue cheese (risk of listeriosis)
Avoid undercooked or raw poultry (risk of salmonella)
Continue moderate exercise but avoid contact sports
Sex is safe
Flying increases the risk of venous thromboembolism (VTE)
Place car seatbelts above and below the bump (not across it)

Question 7

Fetal Alcohol Syndrome

Answer 7

Microcephaly (small head)
Thin upper lip
Smooth flat philtrum (the groove between the nose and upper lip)
Short palpebral fissure (short horizontal distance from one side of the eye to the other)
Learning disability
Behavioural difficulties
Hearing and vision problems
Cerebral palsy

Question 8

Smoking

Answer 8

Fetal growth restriction (FGR)
Miscarriage
Stillbirth
Preterm labour and delivery
Placental abruption
Pre-eclampsia
Cleft lip or palate
Sudden infant death syndrome (SIDS)

Question 9

NSAIDS in Pregnancy

Answer 9

Examples of non-steroidal anti-inflammatory drugs (NSAIDs) are ibuprofen and naproxen. They work by blocking prostaglandins. Prostaglandins are important in maintaining the ductus arteriosus in the fetus and neonate. Prostaglandins also soften the cervix and stimulate uterine contractions at the time of delivery.

NSAIDS are generally avoided in pregnancy unless really necessary (e.g. in rheumatoid arthritis). They are particularly avoided in the third trimester, as they can cause premature closure of the ductus arteriosus in the fetus. They can also delay labour.

Question 10

Beta Blockers

Answer 10

Beta-blockers are commonly used for hypertension, cardiac conditions and migraine. Labetalol is the most frequently used beta-blocker in pregnancy, and is first-line for high blood pressure caused by pre-eclampsia.

Beta-blockers can cause:

Fetal growth restriction
Hypoglycaemia in the neonate
Bradycardia in the neonate

Question 11

ACE and ARB

Answer 11

Medications that block the renin-angiotensin system (ACE inhibitors and ARBs) can cross the placenta and enter the fetus. In the fetus, they mainly affect the kidneys, and reduce the production of urine (and therefore amniotic fluid). The other notably effect is hypocalvaria, which is an incomplete formation of the skull bones.

ACE inhibitors and ARBs, when used in pregnancy, can cause:

Oligohydramnios (reduced amniotic fluid)
Miscarriage or fetal death
Hypocalvaria (incomplete formation of the skull bones)
Renal failure in the neonate
Hypotension in the neonate

Question 12

Warfarin

Answer 12

Warfarin may be used in younger patients with recurrent venous thrombosis, atrial fibrillation or metallic mechanical heart valves. It crosses the placenta and is considered teratogenic in pregnancy, therefore it is avoided in pregnant women. Warfarin can cause:

Fetal loss
Congenital malformations, particularly craniofacial problems
Bleeding during pregnancy, postpartum haemorrhage, fetal haemorrhage and intracranial bleeding

Question 13

Sodium Valproate

Answer 13

The use of sodium valproate in pregnancy causes neural tube defects and developmental delay.

There are strict rules for avoiding sodium valproate in girls or women unless there are no suitable alternatives and strict criteria are met to ensure they do not get pregnant. There is a specific program called Prevent (valproate pregnancy prevention programme) to ensure this happens.

Question 14

Lithium

Answer 14

Lithium is used as a mood stabilising medication for patients with bipolar disorder, mania and recurrent depression. It is avoided in pregnant women or those planning pregnancy unless other options (i.e. antipsychotics) have failed.

Lithium is particularly avoided in the first trimester, as this is linked with congenital cardiac abnormalities. In particular, it is associated with Ebstein’s anomaly, where the tricuspid valve is set lower on the right side of the heart (towards the apex), causing a bigger right atrium and a smaller right ventricle.

When lithium is used, levels need to be monitored closely (NICE says every four weeks, then weekly from 36 weeks). Lithium also enters breast milk and is toxic to the infant, so should be avoided in breastfeeding.

Question 15

SSRI

Answer 15

Selective serotonin reuptake inhibitors (SSRIs) are the most commonly used antidepressants in pregnancy. SSRIs can cross the placenta into the fetus. The risks need to be balanced against the benefits of treatment. The risks associated with untreated depression can be very significant. Women need to be aware of the potential risks of SSRIs in pregnancy:

First-trimester use has a link with congenital heart defects
First-trimester use of paroxetine has a stronger link with congenital malformations
Third-trimester use has a link with persistent pulmonary hypertension in the neonate
Neonates can experience withdrawal symptoms, usually only mild and not requiring medical management

Question 16

Isotretonin

Answer 16

Isotretinoin is a retinoid medication (relating to vitamin A) that is used to treat severe acne. It should be prescribed and monitored by a specialist dermatologist.

Isotretinoin is highly teratogenic, causing miscarriage and congenital defects. Women need very reliable contraception before, during and for one month after taking isotretinoin.

Question 17

Rubella in Pregnancy

Answer 17

Rubella is also known as German measles. Congenital rubella syndrome is caused by maternal infection with the rubella virus during the first 20 weeks of pregnancy. The risk is highest before ten weeks gestation.

Women planning to become pregnant should ensure they have had the MMR vaccine. When in doubt, they can be tested for rubella immunity. If they do not have antibodies to rubella, they can be vaccinated with two doses of the MMR, three months apart.

Pregnant women should not receive the MMR vaccination, as this is a live vaccine. Non-immune women should be offered the vaccine after giving birth.

The features of congenital rubella syndrome to be aware of are:

Congenital deafness
Congenital cataracts
Congenital heart disease (PDA and pulmonary stenosis)
Learning disability

Question 18

Chickenpox in Pregnancy

Answer 18

Chickenpox is caused by the varicella zoster virus (VZV). It is dangerous in pregnancy because it can lead to:

More severe cases in the mother, such as varicella pneumonitis, hepatitis or encephalitis
Fetal varicella syndrome
Severe neonatal varicella infection (if infected around delivery)

Mothers that have previously had chickenpox are immune and safe. When in doubt, IgG levels for VZV can be tested. A positive IgG for VZV indicates immunity. Women that are not immune to varicella may be offered the varicella vaccine before or after pregnancy.

Exposure to chickenpox in pregnancy:

When the pregnant woman has previously had chickenpox, they are safe
When they are not sure about their immunity, test the VZV IgG levels. If positive, they are safe.
When they are not immune, they can be treated with IV varicella immunoglobulins as prophylaxis against developing chickenpox. This should be given within ten days of exposure.

When the chickenpox rash starts in pregnancy, they may be treated with oral aciclovir if they present within 24 hours and are more than 20 weeks gestation.

Congenital varicella syndrome occurs in around 1% of cases of chickenpox in pregnancy. It occurs when infection occurs in the first 28 weeks of gestation. The typical features include:

Fetal growth restriction
Microcephaly, hydrocephalus and learning disability
Scars and significant skin changes located in specific dermatomes
Limb hypoplasia (underdeveloped limbs)
Cataracts and inflammation in the eye (chorioretinitis)

Question 19

Listeria in Pregnancy

Answer 19

Listeria is an infectious gram-positive bacteria that causes listeriosis. Listeriosis is many times more likely in pregnant women compared with non-pregnant individuals. Infection in the mother may be asymptomatic, cause a flu-like illness, or less commonly cause pneumonia or meningoencephalitis.

Listeriosis in pregnant women has a high rate of miscarriage or fetal death. It can also cause severe neonatal infection.

Listeria is typically transmitted by unpasteurised dairy products, processed meats and contaminated foods. Pregnant women are advised to avoid high-risk foods (e.g. blue cheese) and practice good food hygiene.

Question 20

Congenital Cytomegalovirus in Pregnancy

Answer 20

Congenital cytomegalovirus infection occurs due to a cytomegalovirus (CMV) infection in the mother during pregnancy. The virus is mostly spread via the infected saliva or urine of asymptomatic children. Most cases of CMV in pregnancy do not cause congenital CMV.

The features of congenital CMV are:

Fetal growth restriction
Microcephaly
Hearing loss
Vision loss
Learning disability
Seizures

Question 21

Congenital Toxoplasmosis in Pregnancy

Answer 21

Infection with the Toxoplasma gondii parasite is usually asymptomatic. It is primarily spread by contamination with faeces from a cat that is a host of the parasite. When infection occurs during pregnancy, it can lead to congenital toxoplasmosis. The risk is higher later in the pregnancy.

There is a classic triad of features in congenital toxoplasmosis:

Intracranial calcification
Hydrocephalus
Chorioretinitis (inflammation of the choroid and retina in the eye)

Question 22

Congenital Parvovirus in Pregnancy

Answer 22

Parvovirus B19 infection typically affects children. It is also known as fifth disease, slapped cheek syndrome and erythema infectiosum. It is caused by the parvovirus B19 virus. The illness is self-limiting, and the rash and symptoms usually fade over 1 – 2 weeks.

Parvovirus infection starts with non-specific viral symptoms. After 2 – 5 days, the rash appears quite rapidly as a diffuse bright red rash on both cheeks, as though they have “slapped cheeks”. A few days later a reticular mildly erythematous rash affecting the trunk and limbs appears, which can be raised and itchy. Reticular means net-like.

Healthy children and adults have a low risk of any complications, and management is supportive. They are infectious 7 – 10 days before the rash appears. They are not infectious once the rash has appeared. Significant exposure to parvovirus is classed as 15 minutes in the same room, or face-to-face contact, with someone that has the virus.

Infections with parvovirus B19 in pregnancy can lead to several complications, particularly in the first and second trimesters. Complications are:

Miscarriage or fetal death
Severe fetal anaemia
Hydrops fetalis (fetal heart failure)
Maternal pre-eclampsia-like syndrome

Fetal anaemia is caused by parvovirus infection of the erythroid progenitor cells in the fetal bone marrow and liver. These cells produce red blood cells, and the infection causes them to produce faulty red blood cells that have a shorter life span. Less red blood cells results in anaemia. This anaemia leads to heart failure, referred to as hydrops fetalis.

Maternal pre-eclampsia-like syndrome is also known as mirror syndrome. It can be a rare complication of severe fetal heart failure (hydrops fetalis). It involves a triad of hydrops fetalis, placental oedema and oedema in the mother. It also features hypertension and proteinuria.

Women suspected of parvovirus infection need tests for:

IgM to parvovirus, which tests for acute infection within the past four weeks
IgG to parvovirus, which tests for long term immunity to the virus after a previous infection
Rubella antibodies (as a differential diagnosis)

Treatment is supportive. Women with parvovirus B19 infection need a referral to fetal medicine to monitor for complications and malformations.

Question 23

Rhesus Incompatibility in Pregnancy

Answer 23

The name rhesus refers to various types of rhesus antigens on the surface of red blood cells. The antigens on the red blood cells vary between individuals. The rhesus antigens are separate to the ABO blood group system.

Within the rhesus group, many different types of antigens can be present or absent, depending on the person’s blood type. The most relevant antigen within the rhesus blood group system is the rhesus-D antigen. When we refer to someone’s rhesus status in relation to pregnancy (e.g. “she is rhesus-negative”), we are usually referring to whether they have the rhesus-D antigen present on their red blood cell surface.

Rhesus Incompatibility in Pregnancy
Women that are rhesus-D positive do not need any additional treatment during pregnancy.

When a woman that is rhesus-D negative becomes pregnant, we have to consider the possibility that her child will be rhesus positive. It is likely at some point in the pregnancy (i.e. childbirth) that the blood from the baby will find a way into the mother’s bloodstream. When this happens, the baby’s red blood cells display the rhesus-D antigen. The mother’s immune system will recognise this rhesus-D antigen as foreign, and produce antibodies to the rhesus-D antigen. The mother has then become sensitised to rhesus-D antigens.

Usually, this sensitisation process does not cause problems during the first pregnancy. During subsequent pregnancies, the mother’s anti-rhesus-D antibodies can cross the placenta into the fetus. If that fetus is rhesus-D positive, these antibodies attach themselves to the red blood cells of the fetus and causes the immune system of the fetus to attack them, causing the destruction of the red blood cells (haemolysis). The red blood cell destruction caused by antibodies from the mother is called haemolytic disease of the newborn.

Management
Prevention of sensitisation is the mainstay of management. This involves giving intramuscular anti-D injections to rhesus-D negative women. There is no way to reverse the sensitisation process once it has occurred, which is why prophylaxis is so essential.

The anti-D medication works by attaching itself to the rhesus-D antigens on the fetal red blood cells in the mothers circulation, causing them to be destroyed. This prevents the mother’s immune system recognising the antigen and creating it’s own antibodies to the antigen. It acts as a prevention for the mother becoming sensitised to the rhesus-D antigen.

Anti-D injections are given routinely on two occasions:

28 weeks gestation
Birth (if the baby’s blood group is found to be rhesus-positive)

Anti-D injections should also be given at any time where sensitisation may occur, such as:

Antepartum haemorrhage
Amniocentesis procedures
Abdominal trauma

Anti-D is given within 72 hours of a sensitisation event. After 20 weeks gestation, the Kleinhauer test is performed to see how much fetal blood has passed into the mother’s blood, to determine whether further doses of anti-D are required.

Kleihauer Test
The Kleihauer test checks how much fetal blood has passed into the mother’s blood during a sensitisation event. This test is used after any sensitising event past 20 weeks gestation, to assess whether further doses of anti-D is required.

The Kleihauer test involves adding acid to a sample of the mother’s blood. Fetal haemoglobin is naturally more resistant to acid, so that they are protected against the acidosis that occurs around childbirth. Therefore, fetal haemoglobin persists in response to the added acid, while the mothers haemoglobin is destroyed. The number of cells still containing haemoglobin (the remaining fetal cells) can then be calculated.

Question 24

Causes for Small for Gestational Age

Answer 24

The causes of SGA can be divided into two categories:

Constitutionally small, matching the mother and others in the family, and growing appropriately on the growth chart
Fetal growth restriction (FGR), also known as intrauterine growth restriction (IUGR)

Fetal growth restriction (FGR), also known as intrauterine growth restriction (IUGR), is when there is a small fetus (or a fetus that is not growing as expected) due to a pathology reducing the amount of nutrients and oxygen being delivered to the fetus through the placenta.

TOM TIP: It is important to note the difference between small for gestational age (SGA) and fetal growth restriction (FGR). Small for gestational age simply means that the baby is small for the dates, without stating why. The fetus may be constitutionally small, growing appropriately, and not at increased risk of complications. Alternatively, the fetus may be small for gestational age due to pathology (i.e. FGR), with a higher risk of morbidity and mortality.

The causes of fetal growth restriction can be divided into two categories:

Placenta mediated growth restriction
Non-placenta mediated growth restriction, where the baby is small due to a genetic or structural abnormality

Placenta mediated growth restriction refers to conditions that affect the transfer of nutrients across the placenta:

Idiopathic
Pre-eclampsia
Maternal smoking
Maternal alcohol
Anaemia
Malnutrition
Infection
Maternal health conditions

Non-placenta medicated growth restriction refers to pathology of the fetus, such as:

Genetic abnormalities
Structural abnormalities
Fetal infection
Errors of metabolism

Other Signs of Fetal Growth Restriction
There may be other signs that would indicate FGR other than the fetus being SGA, such as:

Reduced amniotic fluid volume
Abnormal Doppler studies
Reduced fetal movements
Abnormal CTGs

Question 25

Complications Small for Gestational Age

Answer 25

Short term complications of fetal growth restriction include:

Fetal death or stillbirth
Birth asphyxia
Neonatal hypothermia
Neonatal hypoglycaemia

Growth restricted babies have a long term increased risk of:

Cardiovascular disease, particularly hypertension
Type 2 diabetes
Obesity
Mood and behavioural problems

Question 26

Risk Factors SGA

Answer 26

There are a long list of risk factors for SGA:

Previous SGA baby
Obesity
Smoking
Diabetes
Existing hypertension
Pre-eclampsia
Older mother (over 35 years)
Multiple pregnancy
Low pregnancy‑associated plasma protein‑A (PAPPA)
Antepartum haemorrhage
Antiphospholipid syndrome

Question 27

Monitors and Management SGA

Answer 27

The RCOG green-top guidelines on SGA (2013) lists major and minor risk factors. At the booking clinic, women are assessed for risk factors for SGA.

Low-risk women have monitoring of the symphysis fundal height (SFH) at every antenatal appointment from 24 weeks onwards to identify potential SGA. The SFH is plotted on a customised growth chart to assess the appropriate size for the individual woman. If the symphysis fundal height is less than the 10th centile, women are booked for serial growth scans with umbilical artery doppler.

Women are booked for serial growth scans with umbilical artery doppler if they have:

Three or more minor risk factors
One or more major risk factors
Issues with measuring the symphysis fundal height (e.g. large fibroids or BMI > 35)

Women at risk or with SGA are monitored closely with serial ultrasound scans measuring:

Estimated fetal weight (EFW) and abdominal circumference (AC) to determine the growth velocity
Umbilical arterial pulsatility index (UA-PI) to measure flow through the umbilical artery
Amniotic fluid volume

The local guidelines for the initiation and frequency of ultrasound scans may vary. An example regime is a growth scan every four weeks from 28 weeks gestation. Ultrasound frequency is increased where there is reduced growth velocity or problems with umbilical flow.

Management
The critical management steps are:

Identifying those at risk of SGA
Aspirin is given to those at risk of pre-eclampsia
Treating modifiable risk factors (e.g. stop smoking)
Serial growth scans to monitor growth
Early delivery where growth is static, or there are other concerns

When a fetus is identified as SGA, investigations to identify the underlying cause include:

Blood pressure and urine dipstick for pre-eclampsia
Uterine artery doppler scanning
Detailed fetal anatomy scan by fetal medicine
Karyotyping for chromosomal abnormalities
Testing for infections (e.g. toxoplasmosis, cytomegalovirus, syphilis and malaria)

Early delivery is considered when growth is static on the growth charts, or other problems are identified (e.g. abnormal Doppler results). This reduces the risk of stillbirth. Corticosteroids are given when delivery is planned early, particularly when delivered by caesarean section. Paediatricians should be involved at birth to help with neonatal resuscitation and management if required.

Question 28

Causes of Macrosomia/Large for Gestional Age

Answer 28

Constitutional
Maternal diabetes
Previous macrosomia
Maternal obesity or rapid weight gain
Overdue
Male baby

Question 29

Risks for Macrosomia

Answer 29

The risks to the mother include:

Shoulder dystocia
Failure to progress
Perineal tears
Instrumental delivery or caesarean
Postpartum haemorrhage
Uterine rupture (rare)

The risks to the baby include:

Birth injury (Erbs palsy, clavicular fracture, fetal distress and hypoxia)
Neonatal hypoglycaemia
Obesity in childhood and later life
Type 2 diabetes in adulthood

TOM TIP: If you only remember two things about macrosomia, remember that it is caused by gestational diabetes, and there is a significant risk of shoulder dystocia during birth.

Question 30

Treatment

Answer 30

Investigations for a large for gestational age baby are:

Ultrasound to exclude polyhydramnios and estimate the fetal weight
Oral glucose tolerance test for gestational diabetes

Most women with large for gestational age pregnancy will have a successful vaginal delivery. NICE guidelines (2008) advise against induction of labour only on the grounds of macrosomia.

The main risk with a large for gestational age baby is shoulder dystocia. The risks at delivery can be reduced by:

Delivery on a consultant lead unit
Delivery by an experienced midwife or obstetrician
Access to an obstetrician and theatre if required
Active management of the third stage (delivery of the placenta)
Early decision for caesarean section if required
Paediatrician attending the birth