Articles

Folic Acid & Pregnancy

Taking a folic acid supplement before you conceive and for the first three months of pregnancy can reduce your chances of having a baby with a neural tube defect such as spina bifida.

Spina bifida is a serious abnormality of the spinal cord and the bones, muscles and skin covering it. Other neural tube defects affect the development of the brain as well as the spinal cord. This can cause a wide range of disabilities.

Folic acid is a water soluble B-group vitamin. The vitamin is known as folate when it is found naturally in food and folic acid in tablet form. It can be found naturally in most green leafy vegetables (asparagus, brussel sprouts, broccoli, spinach), wholegrain breads and cereals and some fruits (oranges, bananas, strawberries). Folate is vulnerable to heat and dissolves in water so cooking can reduce the levels of folate in foods. Prolonged storage of certain foods is also thought to reduce their folate levels. Therefore most women do not get enough folate from diet alone.

Women planning on getting pregnant need an additional 500mcgms/day via a supplement. They should also ensure their diet includes foods rich in natural folate as well as choosing foods that have been fortified with folate such as certain breads, breakfast cereals and fruit juices.

Folic acid tablets are available from the pharmacy, supermarkets and health food stores. Most pregnancy multivitamins such as Elevit or Blackmores Gold contain folic acid in combination with other vitamins and minerals.

It is not possible to consume “Too much” folate – it is the same as taking any other water soluble vitamin supplement.

Some women are at greater risk of having a baby with a neural tube defect. It is important to discuss with your doctor if you have had a previous child with a neural tube defect, you or a close relative have a neural tube defect or you are taking medication for epilepsy as some medications affect the absorption of folate and higher doses may be required.

Iodine Supplements

Iodine is essential for the brain development and thyroid function of the growing fetus. Deficiency in iodine can lead to intellectual impairment and developmental problems. Recent research suggests that Australian women are not getting enough iodine in their diet when pregnant and whist breastfeeding.

Surprisingly few foods are good sources of iodine. As the body cannot store iodine, a small amount must be consumed every day. The richest, natural food sources of iodine are found in seafood and seaweed such as kelp and nori. Iodine levels in foods of animal origin (eggs, meat and dairy products) are higher than most foods of plant origin.

It is therefore recommended that all pregnant women and those breastfeeding should be taking iodine supplements in doses between 100ug and 200ug per day. Some pregnancy supplements such as Blackmores Gold and Cenovis A Pregnancy and Breastfeeding Formula contain iodine as well as folate.

The only exception to this recommendation are women with known thyroid disease.

Diet & pregnancy

It is important to eat a nutritious and varied diet during pregnancy. There is a need for certain nutrients such as iron, folate and calcium to be increased during this time but only a slight increase in kilojoules is required. The saying “eating for two” as such is a myth. A healthy weight gain during pregnancy will vary between individuals, but is thought to be between 10-15kg.

Pregnancy is not a suitable time to be dieting or trying to lose weight. It is more beneficial to focus on good, nutritious food rather than quantity to meet the nutritional needs of pregnancy.

Recommended servings per day of the 5 main food groups:

Cereals – bread, rice, pasta, noodles: 4-6 serves / day
Vegetables / legumes – 5-6 serves / day
Fruit – 4 servings / day
Dairy products – milk, cheese, yoghurt – 2 servings / day
Protein – poultry, fish, meat, eggs – 1 1/2 servings / day

Foods to be avoided in pregnancy:
Precooked or prepared cold foods that cannot be preheated eg. salads, delicatessen meats such as ham or salami.
Semi soft and surface ripened cheese, unpasteurised dairy products, soft serve ice cream, pate.
Smorgasbord / salad bars.
Chilled, smoked or uncooked fish or seafood products.
The organism that causes listeria is destroyed during the cooking process so cooked, hot food does not cause risk.
Limit foods that are high in sugar, fats and salt to being occasional treats.
Limit your alcohol intake if you choose to drink. Research has shown that there is no know “safe” amount to drink during pregnancy. It is therefore best to avoid drinking alcohol during pregnancy as much as possible.

Mercury in fish
It is advisable to eat 1-2 meals per week containing fish. There are however, a few types of fish that need to be limited due to their high mercury content which can be harmful to the developing fetus. It is only a potential problem when this type of fish is eaten regularly. These are: billfish (swordfish, broadbill, marlin), shark (flake), orange roughy (seaperch), gemfish, catfish. Limit other fish such as tuna steaks to one portion per week or two 140gm cans of tuna per week. There is no restriction needed on the amount of salmon consumed.

The Pelvic Floor

The pelvic floor is the supportive “hammock – like” layer of muscles that supports the pelvic organs – the bladder, bowel and uterus and the passages that lead out of the body – the vagina, the urethra (outlet from the bladder) and the anus (back passage).

Like any other muscle group, the pelvic floor needs to be strengthened by exercise to avoid it becoming weakened and less efficient. This is particularly important during pregnancy when the growing uterus may cause the pelvic muscles to sag. Other reasons for the pelvic floor muscles to weaken are – constipation, lack of exercise, heavy lifting, being overweight and family history.

Signs that your pelvic floor is weak are incontinence of urine (especially during exertion such as sneezing, coughing or lifting), a feeling of heaviness in the vagina and tampons slipping out.

The pelvic floor muscles can be strengthened provided that they are regularly exercised. Either train yourself to do them, ask your doctor or consult a physiotherapist who has an interest in women’s health. Our office has a list of recommended physiotherapists. Pelvic floor exercises can be done anytime, anywhere. It may take several months before you notice the benefit, so persistence is essential.

Mammograms

A mammogram is a simple, safe X-Ray examination of the breast. The word comes from mamma, meaning breast and graphe meaning drawing.

A mammogram is performed at a radiology practice by a trained technician who performs the procedure with specially designed X-Ray equipment. A special device is used to flatten the breast to produce uniformed thickness. This compression of the breast may cause mild discomfort but most women do not consider it painful and the discomfort lasts only a few seconds.

The entire procedure takes on 10 -15 minutes. It is best to schedule your appointment for a mammogram following your period when your breasts are less likely to be tender. A radiologist interprets the mammogram and sends a written report to the referring doctor.

Our practice recommends:

• A breast self-examination every month beginning at age 18.
• A yearly physical breast examination when you have your pap smear or as part of your gynaecological check up.
• A routine mammogram every two years from the age of 40.

These recommendations are intended for women who have no breast symptoms and have no family history of breast cancer. It is important that if any symptoms develop between appointment times that you consult your doctor.

Breast Cancer Facts

Breast cancer is the major cause of cancer death in Australian women accounting for more than 11,700 new case of breast cancer and 2600 deaths each year. Early detection is the best method for reducing deaths from breast cancer. Women whose cancer is still contained in the breast when diagnosed have a 90% chance of surviving five years, compared with a 20% five year survival chance when the cancer has spread at diagnosis.

Fast facts

• -Breast cancer is still the most common cancer among Australian women after non-melanoma skin cancer.
• One in 11 women will be diagnosed with the disease by the age of 75.
• In 2002 a total of 12,027 women were diagnosed with breast cancer in Australia. It is projected that there will be 14,818 diagnosed in 2011.
• A total of 2641 women died from breast cancer in 2004 making it the most common cause of cancer related death in women.
• Despite the substantial loss of life, prospects for survival are better than ever. Currently in Australia, over 96.7% of women diagnosed with breast cancer will survive for at least one year and 86.6% will survive for five years or longer.
• From 1994 to 2003, the breast cancer death rates declined by an average of 2% per year. Survival is improving due to better and earlier detection and improved treatment resulting from excellent research.
• Breast cancer survivors often encounter problems ranging from physical limitations to psychosocial difficulties following diagnosis and treatment. Researchers have begun to systematically study the recovery pathways experienced by women.
• As with most cancers, the risk from breast cancer increases with age. 25% of new breast cancers diagnosed in 1999 were among women aged 20-49; 48% among women aged 50-69; and 27% among women 70+. The average age of first diagnosis was 60 years for a woman in 2002.
• It is recommended that women of all ages are aware of how their breasts normally look and feel and report any new or unusual changes promptly to their doctor.
• In the 2001 National Health Survey, 12.2% of women aged 50-59 years, 11.2% of those aged 60-69 and 27% of those 70 years+ reported that they had never had a mammogram.
• Over 70% of breast cancer cases are found in women aged 50 years and older. In younger women, tumours are likely to be larger and more aggressive, resulting in a lower rate of survival than for older women.

Source: Breast Cancer in Australia: An Overview, 2006 National Breast Cancer Foundation

Emergency Contraception

Each year there are many unplanned and often unwanted pregnancies due to lack of contraception or contraception failure. Although effective contraception is readily available, there are times when a condom will break or a woman will forget to take her pill. Emergency contraception provides a safe and effective emergency method for birth control in such situations.

Whilst there are a number of emergency contraceptive methods available, they require use preferably within 24 hours of intercourse. As they are not as effective as the pill or condoms, they should not be used as a routine contraceptive method. Daily, correct use of the contraceptive pill prevents 97 -99% of pregnancies whilst the emergency method has about an 85% success rate. Therefore as the name implies, it should be used for emergency use only.

The most common method of emergency contraception involves taking Postinor-2.
This can be purchased without a script from a pharmacy.
Take one tablet as soon as possible (within 72 hours) after you have had unprotected intercourse. Take the second tablet 12 hours after the first tablet.

It is thought that Postinor-2 works by:

• Stopping the ovaries from releasing an egg
• Prevents sperm from fertilizing any egg that may have been released
• Stops a fertilized egg from attaching itself to the lining of the uterus

Prostinor-2 helps stop a pregnancy before it is established. It does not work if you are already pregnant. There are some medical conditions such as Crohn’s disease, liver problems and high blood pressure that may make this type of medication unsuitable for you. There are also certain medications that may prevent Postiner-2 from working effectively. It is important that you discuss this with your doctor. Like most medications there may be side effects with taking Postinor-2. These include nausea, irregular spotting, tender breasts and mild gastro intestinal symptoms. You should expect a period within 21 days of taking Postinor-2 and if this does not happen it is important to consult your doctor to rule out pregnancy.

Whooping cough

Description

Whooping cough (or pertussis) is a highly contagious respiratory infection caused by bacteria. It can affect babies, children and adults. For adolescents and adults the infection may only be a persistent cough, however for young children whooping cough can be life threatening. The cough can obstruct a baby’s breathing and they may lack oxygen and become blue.

Pertussis (whooping cough) is caused by the bacterium Bordetella Pertussis. The disease is highly infectious and most serious in babies. Babies are at greatest risk of infection until they can have at least two doses of the vaccine (minimum 4 months old) as the mother’s antibodies do not provide reliable protection. It is spread through droplets in the air and it can develop from upper respiratory tract (nose, throat and windpipe) infection into pertussis pneumonia (lung infection).

A single booster dose of dTpa is recommended for both partners planning for pregnancy, parents and for grandparents and other carers of young children as soon as possible after delivery of an infant.

The protection provided by childhood vaccination gradually reduces over time’ leaving adolescents and adults potentially at risk of catching the disease. An adult-adolescent whooping cough vaccine, combined with diphtheria and tetanus vaccine (dTpa)’ is now available.

Symptoms

Whooping cough may start like a cold, with a runny nose and sneezing, and then the characteristic cough develops. These coughing bouts can be very severe and frightening, and may end with a crowing noise (the whoop). This occurs as air is drawn back into the chest, and can be followed by vomiting or gagging. In young infants, as well as older children and adults, the typical symptoms may not be present.

After exposure to the bacteria, it usually takes nine to ten days to become ill.

Transmission

The bacteria are spread by an infected person coughing or sneezing. Direct contact with the infection secretions from the mouth or nose can also pass on the infection.

A person is highly infectious for the first two weeks of their cough. After three weeks of coughing, the person is regarding as non-infectious, even though coughing may last up to three months.

Treatment

Treatment is a full course of antibiotics which reduces the time a person is infectious to others. Antibiotics need to be given within 21 days of the start of general symptoms or within 14 days of the start of the cough. Antibiotics reduce symptoms if given when infection is developing, after contact with a person with pertussis and in the early coughing stage.

Not all people who have close contact with an infected person with whooping cough need treatment. However, because infants are at a higher risk of severe complications if they develop whooping cough, a full course of antibiotics is recommended for the following people in the same house as a person with whooping cough (if the infected person has been coughing less than 21 days). This includes:

• any baby less than 12 months of age regardless of their vaccination status
• any child between 12-24 months of age who has received less than three doses of a whooping cough vaccine
• any woman in the last month of pregnancy
• any child or adult who attends or works in a childcare centre.

If a child with whooping cough attends childcare and belongs to the infant group (less than 12 months of age), the other infants in that group should be given antibiotics if the infected child has been coughing less that 14 days.

Control

A person with whooping cough should stay away from work, school and child-care until they have had full course of antibiotics. or until 21 days after the beginning of the coughing or until the end of coughing, whichever comes first.

Household contacts, who have received less than three doses of whooping cough vaccine, should be excluded from child-care centers until they have taken a full course of antibiotics or for 14 days after the last exposure to infection.

Prevention

Whooping couch can be prevented by vaccination. The whooping cough (pertussis) vaccine is combined together with diphtheria, tetanus and inactivated poliomyelitis vaccine (DTPa-IPV).

Vitamin D Deficiency in Pregnancy

Vitamin D deficiency is a very common problem. It is estimated in Australia that one in three adults and 80% of all pregnant women are vitamin D deficient. Vitamin D deficiency may also result from some chronic medical conditions and certain medications.

Ninety percent of our vitamin D is made in the skin via sun exposure. Vitamin D deficiency is therefore thought to be contributed to the general community being more aware of the harmful effects of sun exposure and the fact that we live in the southern regions of Australia.

Most foods contain very little vitamin D naturally although some margarines, cereals and milk are fortified with added vitamin D.

It is important to maintain healthy vitamin D levels during pregnancy as it assists in maintaining muscle and bone strength, allows your body to absorb calcium and is an important nutrient for the growth and development of the baby’s muscle/skeletal system.

Vitamin D levels are checked routinely during your pregnancy at your initial consultation. If you are identified as having a low vitamin D level, you will need to take a supplement. This is in addition to the pregnancy multivitamin that you should already be taking such as
Blackmore’s Gold or Elevit. We recommend Ostelin or Oste-Vit D which is available at the pharmacy. You will need to take two capsules/tablets twice a day. Your vitamin D levels will be rechecked at 28 weeks gestation when we do your diabetic screening. Depending upon this result, your dosage may be increased until you deliver.

There is very little vitamin D in breast milk so you will need to purchase a liquid vitamin for
your baby from your pharmacy called Pentavite. You will be advised by one of the midwives in hospital regarding the dosage and how to administer Pentavite. Your Maternal and Child Health Nurse will advise you about administration and dosage after your discharge from hospital.

For women who have had low vitamin D levels during pregnancy, in the long term it is important to continue taking a vitamin D supplement to protect against health problems such as osteoporosis. You can follow this up with your regular GP who can arrange further testing to ensure that your vitamin D levels have stayed within the normal range and adjust the dose of your supplement accordingly.

Thyroid conditions in pregnancy

The thyroid gland
The thyroid gland produces two hormones Triiodothyronine (T3) and Thyroxin (T4).
Thyroid hormones (T3 and T4) affect the body’s metabolism and a number of bodily functions including the function of the nervous system, muscles, digestive system, skin, menstrual cycle, etc. The release of thyroid hormone from the thyroid gland is controlled and regulated by thyroid stimulating hormone (TSH) which is produced by the pituitary gland which is located at the base of the brain. The release of thyroid hormone is controlled by a feedback mechanism – when thyroid hormone levels are too low the body produces more TSH from the pituitary and this releases more of the thyroid hormone from the thyroid gland to make up for the deficit.

Changes in the thyroid gland and thyroid hormone production in pregnancy
In a normal pregnancy there is an increase in the metabolic needs of the mother and there are therefore changes in thyroid function and physiology due to these increased demands. There is therefore an increased output from the thyroid gland of the thyroid hormones T3 and T4. The thyroid gland itself enlarges symmetrically indicating this increase in thyroid hormone production. Some of the hormones that are produced by the placenta during a normal pregnancy do affect the physiology of the thyroid gland. For example, female oestrogen hormone which is produced in large amounts during the pregnancy increases the level of TBG, or thyroid binding globulin, which is the hormone that carries thyroid hormone. Similarly hCG, which is a hormone produced only when you are pregnant by the chorionic or placental tissue is very similar in structure to the TSH produced by the pituitary gland. Because of this it combines to TSH receptors throughout the body and influences thyroid hormone production via the feedback mechanism discussed above. For this reason the interpretation of thyroid hormone levels varies in pregnant women as compared to non-pregnant women. This information is well known by your general practitioner and obstetrician. In particular the interpretation of TSH levels in the first trimester of pregnancy (up to 12 weeks) needs to allow for the physiological changes that occur during pregnancy. In particular the production of hCG pregnancy hormone results in a decline in TSH levels and the diagnosis of an underactive thyroid gland needs to take into account these normal bodily changes.

The thyroid and the fetus
Thyroid hormone has been shown to be particularly important in fetal development and plays a crucial role in fetal brain development. The fetus starts producing thyroid hormone itself between 10 and 12 weeks’ gestation. The fetus is able to concentrate iodine into the fetal thyroid and synthesize thyroid hormones. However, the level of this thyroid hormone does not reach significant levels until 18 – 20 weeks. The fetus is therefore largely dependent, especially in the first and early second trimester, on the transfer across the placenta of maternal thyroid hormone.

Iodine intake in pregnancy
Iodine is essential for the production of thyroid hormone.
Due to the increase in the production of thyroid hormone during pregnancy – by up to 50% compared to non-pregnant women, iodine requirements are increased during pregnancy. The World Health Organisation recommends 250mcg a day of iodine in both pregnant and lactating women. An average Australian diet usually results in 100mcg of iodine per day being ingested and therefore pregnancy supplements should contain 150mcg a day of iodine to meet the World Health Organisation requirements. The commonly prescribed pre-natal vitamins such as Elevit with iodine and Blackmore’s Pregnancy and Lactation formula therefore contain adequate amounts of iodine to meet the increased requirements for thyroid hormone production. The daily level of iodine intake should not exceed 1000mcg per day.

Thyroid checks in pregnancy
There is still some controversy as to whether all pregnant women should be tested for thyroid conditions in pregnancy, or whether screening should only occur in patients who are thought to be at risk. Patients at risk are particularly women who have had an obstetric complication known to be associated with thyroid disease, such as recurrent miscarriages, women who have symptoms of thyroid disease, women who already have an autoimmune disorder, women with a family history etc. However, I am a strong believer in universal screening. As a number of studies have shown delayed neurological development in the offspring of women who have even mildly underactive thyroid glands, it would seem a simple screening test should be performed at 8 – 10 weeks’ gestation. This is because if an underactive thyroid gland is found at that time then replacement hormone therapy will have started before the crucial time of fetal brain development. Patients who need to be placed on treatment for a thyroid condition throughout their pregnancy need to be monitored via thyroid hormone levels during pregnancy as the severity of any thyroid condition can change as the pregnancy progresses.

The underactive thyroid – hypothyroidism
Up to 5% of all pregnant women will have an underactive or overactive thyroid condition in pregnancy which can be diagnosed on blood testing. The incidence of thyroid disease in pregnancy varies between different countries, largely because of the varying incidence of iodine deficiency. In the absence of iodine deficiency the most common cause of an underactive thyroid gland in pregnancy is a chronic autoimmune condition called Hashimoto’s thyroiditis.

Other causes of an underactive thyroid gland can be if a woman has had treatment of an overactive thyroid gland in the past with radioactive iodine which destroys part of the thyroid gland and can result in an underactive thyroid gland. Hypothyroidism can had adverse effects on both the mother and child. Several complications in pregnancy have been associated with hypothyroidism or an underactive thyroid gland. These include high blood pressure in pregnancy, pre-term or premature delivery, low birth weight or growth restricted infants, increased risk of stillbirth and as mentioned previously neurodevelopmental and cognitive impairment, in other words, delayed development in the infant.
It is important to realise that even women with sub-clinical hypothyroidism, which means that they have an underactive thyroid gland but no symptoms at all, are at risk of complications during their pregnancy. This diagnosis is based purely on the results of blood testing in the first trimester. The incidence of stillbirth, premature delivery and low birth weight babies has been shown to be increased in sub-clinical hypothyroidism but the developmental problems in the infant may be a less certain problem.

An overactive thyroid – hyperthyroidism
The most common cause of hyperthyroidism in pregnancy is a transient increase in thyroid hormone levels early in pregnancy associated with the normal production of hCG or pregnancy hormone. This condition cures itself usually in the second trimester and is called gestational thyrotoxicosis. No treatment is usually required. The most common cause of persisting hyperthyroidism in pregnancy is a condition called Grave’s disease resulting in an increase in production of thyroid hormone during the pregnancy. Patients with Grave’s disease may already be on treatment with a medication called PTU (Propylthiouracil). This medication has been shown to be safe in pregnancy and it is important that hyperthyroidism is adequately treated during the pregnancy. Hyperthyroidism is less common than hypothyroidism and only affects about 0.4% of all pregnancies. The usual cause of hyperthyroidism, Grave’s disease, usually becomes less severe later in the pregnancy and therefore the dose of medication required to control the condition can usually be reduced. Hyperthyroidism especially if untreated can be associated with miscarriage, premature labour, low birth weight babies, stillbirth and high blood pressure in pregnancy.

Postnatal thyroid issues
Up to 5% of pregnant women may develop a condition called postpartum thyroiditis. In this condition women develop either an overactive or underactive thyroid gland in the first few months after childbirth. It is important that this condition is diagnosed as the symptoms can be debilitating and it is crucial therefore that an accurate diagnosis is made. Women with this condition often present with fatigue and general lethargy and malaise. The condition is often self-limiting and resolves itself. It can however recur in subsequent pregnancies.

Beta (β) thalassaemia

What is Beta (β) thalassaemia?

Thalassaemia is a group of blood disorders affecting haemoglobin production. Haemoglobin is a protein in the blood that carries oxygen around our bodies. Thalassaemia is passed from parent to child in genes. Genes carry information about human characteristics such as eye colour, hair colour and haemoglobin.

Thalassaemia is inherited.
Thalassaemia is not contagious.
Thalassaemia is not transmitted by germs.

Sometimes changes occur to genes, resulting in medical conditions. Such changes occur to beta globin genes in beta (β) thalassaemia:

• A person normally inherits two β globin genes for the production of the beta globin protein in haemoglobin.
• A person may have an alteration (mutation) in one of their two β globin genes. This person is called a carrier of β thalassaemia and is healthy. Doctors may use the term β thalassaemia minor instead but it means the same thing.
• Carriers may be at risk of having a child affected
  with beta thalassaemia major if their partner is also a carrier of β thalassaemia.
• When a person has alterations (mutations) in both of their β globin genes, they have a severe condition called β thalassaemia major . β thalassaemia major results in severe anaemia requiring life long treatment.

Treatment for β thalassaemia major

Those with β thalassaemia major require regular blood transfusions every 3 to 4 weeks to correct anaemia. Complications of their treatment include accumulation of excess iron, which can be effectively prevented and managed with medication.

The health of carriers of β thalassaemia

A carrier can expect to be healthy. It is important that their doctor knows they are a carrier to distinguish any anaemia from anaemia caused by low iron levels.

Beta thalassaemia and family planning

The genes for β thalassaemia are common in people of Middle Eastern, Mediterranean, Indian sub-continent and South-East Asian backgrounds. Couples planning a family, or early in pregnancy, should have a blood test to determine whether or not they are carriers, if the origin of either of their families is one of the areas listed above; or if they have a family history of any blood disorder or anaemia. This test is needed to determine if there is any risk of having a child affected by a genetic blood disorder.
Those at risk of having an affected child have options. This condition can be diagnosed as early as the 12th week of pregnancy. Termination of pregnancy can then be considered, if appropriate. People can adopt or can consider assisted reproductive techniques (such as preimplantation genetic diagnosis, the use of donor eggs or donor sperm). Others may choose to take the chance of having an affected child. All of these options can be discussed with a Genetic Counsellor. Testing can be arranged by your local doctor or by contacting the hospitals listed at the end of this pamphlet.

Important information for your family

If you are a carrier of beta thalassaemia, other members of your family may also be carriers and at risk of having children with a severe blood condition. It is recommended that other family members and their partners be tested for their carrier status prior to having children of their own.

Useful contacts
Mercy Hospital for Women
Genetics
163 Studley Road,
Heidelberg VIC
Australia 3084
Phone: +61 3 8458 4250

Monash Medical Centre
Medical Therapy Unit
246 Clayton Road,
Clayton VIC
Australia 3168
Phone: +61 3 9594 2756

Royal Women’s Hospital
Thalassaemia Clinic
Cnr Grattan St & Flemington Rd
Parkville VIC
Australia 3052
Phone: +61 3 8345 2180

Available Genetic Testing in Pregnancy

During the past twelve months, there has been an expansion in the availability of genetic testing for pregnant women. There are screening tests now available that predict the chance of your baby having a certain genetic or chromosomal condition that may seriously interfere with their quality of life.

It is therefore important that I summarise the available tests for you and that you read this document prior to your initial antenatal consultation. At your first antenatal visit, we will discuss these tests in more detail and determine whether or not you feel a particular test is appropriate for you.

• Maternal Serum Screening (MSS)

Maternal Serum screening (MSS) is a blood test offered to pregnant women who wish to find out what their risk is of having a baby with Down’s Syndrome, neural tube defects such as spina bifida or trisomy 18. The blood test does not diagnose these conditions but tells us whether or not you are at an increased risk of having a baby with one of these conditions.

The MSS test is via a blood test taken from the mother at ten weeks gestation. An ultrasound is then performed at 12 weeks gestation. At this ultrasound, measurements are taken of the thickness of the skin on the back of the fetal neck and the fetal nasal bone is measured. The results of your blood tests and the measurements taken at ultrasound are combined with the mother’s maternal age to calculate your risk of having a baby with one of these abnormalities.

If your result indicates that you are at high risk, options are discussed in detail. To accurately confirm or exclude a diagnosis, an amniocentesis or CVS will need to be performed.

• VCGS Reproductive Genetic Carrier Screening

This is a new test that has become available over the past 12 months that screens for carriers of cystic fibrosis, fragile X syndrome and spinal muscular atrophy. This simple blood test is performed on the mother at ten weeks gestation and the test itself diagnoses 90% of people who are carriers of cystic fibrosis, fragile X syndrome and spinal muscular dystrophy.

The test will therefore not detect every person who is a carrier of one of these conditions. The three conditions mentioned here are the three more common genetic diseases that we see in our community. One in 25 individuals is a carrier of cystic fibrosis; one in 150 individuals is a carrier of fragile X syndrome and one in 40 individuals will be a carrier of spinal muscular atrophy. These conditions are known as autosomal recessive conditions meaning that the fetus would require two copies of this gene abnormality to have the condition. Therefore both parents would have to carry the faulty gene.

If the mother tests positive then a test would need to be taken from the father of the child. The blood test is taken at 10 weeks gestation and costs $385. As yet there is no Medicare rebate for this test.

• Non-invasive Prenatal screening (NIPS)

A new test has become available called the NIPS (Panorama Test) which is performed via the Victoria Clinical Genetics Service at the Murdoch Institute at the Royal Children’s Hospital. The basis of this test is the fact that small amounts of fetal DNA normally pass into the maternal circulation at an early stage during the pregnancy. Procedures have been developed allowing this fetal DNA to be collected and analysed. This fetal DNA carries the genetic material of the developing fetus. By using this blood test, the laboratory can screen for the common genetic conditions such as Downs’s Syndrome, Edward Syndrome (a condition where an additional number 18 chromosome is carried) and Patau Syndrome (where an extra number 13 chromosome is carried). This test is also able to diagnose abnormalities involving the sex chromosomes X and Y.

This test is also suitable for twin pregnancies.

These conditions are known as trisomy’s and are usually associated with intellectual disabilities as well as abnormalities of the developing organ systems in the fetus including the heart, kidneys and brain. The test itself has an accuracy of over 99% hence no further testing is usually required. The test is performed via blood test and taken after nine weeks’ gestation. The result itself takes ten working days.

The NIPS test is available for all pregnant women but should especially be considered for women who have a higher chance of having a baby with a chromosome abnormality, either because of their age, family history or because of an abnormality on other screening test results.

At present, this test carries no Medicare rebate and costs approximately $550.

• CVS/Amniocentesis

A CVS or an amniocentesis are invasive procedures performed at 12 weeks and 16 weeks respectively to obtain a sample of either amniotic fluid or trophoblastic tissue to detect any chromosome abnormalities in the fetus.

Specific genetic conditions can also be diagnosed if there is any reason to expect their presence or if there is a family history or previous history of having a child with an abnormality. There are risks associated with such invasive procedures and I will discuss the advantages and disadvantages of invasive procedures when you are seen at your initial antenatal consultation.

• Maternal Karyotyping/Microarray Testing

Currently on a CVS or amniocentesis test, the genetic laboratory carries out a Karyotype test that looks for abnormalities in whole or large sections of chromosomes which carry our genetic information

A new test called a Microarray is capable of finding abnormalities in much smaller sections of genetic material.

The Microarray therefore looks for deletions and duplications using over 300,000 markers for small sections of chromosomes.

A Microarray is indicated especially where there is an unexplained abnormality in a fetus on ultrasound. For example; a child may have a condition called Di George Syndrome where there are serious cardiac abnormalities and developmental delays. This condition is caused by a deletion of a small segment of chromosome 22.

This condition would be missed on the usual karyotype test performed after an amniocentesis or CVS. However, the Syndrome would be picked up on a Microarray.

In the future, Microarray testing may replace karyotype techniques.

• Ultrasounds at 12 and 20 week gestation

The genetic testing already mentioned focuses on the most common genetic anomalies but do not screen for structural defects in the fetus.

A scan at 12 weeks should be still performed to detect major structural defects such as spina bifida.

A more detailed scan at 20 weeks gestation provides a detailed structural survey of the fetus including the brain, spine, heart, other internal organs and the limbs.

In conclusion:

There are now a number of tests available to exclude a genetic condition in your fetus. The testing has become more complex purely because of the increase in availability and the advancements in the type of tests. It is important that these tests are discussed individually with each patient to ascertain what the most appropriate test is for you.

If you begin down the path of screening, I believe you should at least be prepared to have an invasive test to have accurate information on which to base further decisions. You may feel that you would prefer not to have any testing at all either for religious or ethical reasons and that is always taken into consideration and respected. If you choose to have a MSS test, this is just an indication of a probability of a condition being present and often one of the above invasive tests are required to confirm or reassure and these tests carry a small risk of miscarriage.

If you would like to acquire further information about genetic testing please visit VCGS (Victorian Clinical Genetic Services).