Blog Post

Non-Invasive Prenatal Testing/Screening (NIPT/NIPS) or cell free DNA (cfDNA) screening 

  • By websitebuilder
  • 23 Jul, 2018

NIPT screens for certain conditions caused by an abnormal number of chromosomes. It is important to note that it does not screen a pregnancy for all types of chromosomal disorders. The major conditions that are screened include Trisomy 21 (Down syndrome), Trisomy 18 and Trisomy 13. In these conditions, there are 3 copies of the particular chromosome instead of the normal 2 copies. For example, Trisomy 21 means that there are 3 copies of chromosome 21. NIPT also accurately predicts the gender and can detect sex chromosome abnormalities e.g. Turner syndrome. This screening test can be performed from 10 weeks until the baby’s birth. Before we go any further, it is important to distinguish between a screening test versus a diagnostic test.

A screening test is used to estimate whether the baby has a higher risk or a lower risk for a certain condition. This is different to a diagnostic test which will give you a definite answer about whether the baby actually has that condition. These tests include diagnostic tests like chorionic villous sampling (CVS) and amniocentesis.

So how is NIPT performed? Some of the baby’s genetic material (DNA) from the pregnancy can be found circulating in the mother’s blood along with the mother’s DNA. By taking a sample of the pregnant mother’s blood, NIPT can be performed. After the blood sample is collected, the laboratory is able to check for the presence of an abnormal amount of the baby’s DNA for chromosomes 21,18 and 13.

The result from NIPT usually takes the form of a “low risk” (less than 1 in 10,000 chance of an affected baby) or “high risk” (greater than 99% chance of an affected baby). As NIPT can sometimes produce a false high-risk result (false positive), the high result requires confirmation with a diagnostic test such as CVS or amniocentesis before making any decisions about the pregnancy.

There are other important considerations to note. On occasion, the percentage of the baby’s DNA (fetal fraction) in the mother’s blood stream may be too low (less than 4%) to produce an accurate result. This will occur in approximately 1 in 50 NIPT tests and will require another blood test and a delay in results. The percentage of the baby’s DNA in the maternal blood can be affected by the gestational age of the pregnancy, the mother’s weight and in certain multiple pregnancies.

The ideal time to draw the blood sample is from 10 weeks gestation when the fetal fraction is sufficient to perform the test. Further, NIPT cannot be performed in pregnancies where there are more than 2 babies such as in triplet and higher order pregnancies. Lastly, maternal weight will have an impact on the fetal fraction. Over 50% of mothers whose weight is greater than 160 kg will have a foetal fraction below what is required to perform the test accurately. Mothers also need to be aware that results take approximately one week to become available and there is a direct cost to the mother. The cost is approximately $400 and is not Medicare rebatable or refundable through private health insurance.

While NIPT is currently the most efficient screening test available in screening for Down Syndrome, the most appropriate way to implement NIPT within Australia is yet to be determined. There is no doubt that in current clinical obstetric practice, NIPT will be complementary to combined first trimester screening (nuchal fold measurement and placental protein biochemistry) which is already performed between 11 and 14 weeks. Combining NIPT with the 11 to 14-week scan will maintain the benefits of the first trimester scan which includes early detection of abnormalities in the baby and genetic syndromes as well as the opportunity to screen for the development of preeclampsia and other adverse outcomes in the pregnancy while improving the detection of common chromosome abnormalities to above 98%.

 

Currently there are 2 approaches to the use of NIPT testing. The first is to offer NIPT at 10 weeks to screen for the common chromosomal abnormalities and then review the NIPT result with the 11 to 14-week anatomy scan and placental biochemistry. Alternatively, the mother can be offered the traditional 11 to 14-week scan and given a risk assessment for the common chromosomal problems. If the risk is very high (greater than 1 in 50) then diagnostic testing with CVS or amniocentesis would be recommended to detect the rarer chromosomal abnormalities and genetic syndromes of which these women are at increased risk but not detectable with NIPT. A Down Syndrome risk below 1000 may be sufficiently reassuring for the mother who may not wish to do further testing. However, for the smaller population of women who have a risk between 1 and 50 and 1 in 1000, NIPT may be an option.

 

NIPT is an exciting addition to prenatal testing and after appropriate counselling many mothers may opt for NIPT to be performed in their pregnancy. This is an important discussion to have with your Obstetrician. Dr Mary Norris at Newcastle Obstetrics and Ultrasound for Women can assist you with this decision making.

 

References:

www.ranzcog.edu.au

www.acog.com

By websitebuilder September 17, 2019

Are you feeling exhausted with your pregnancy, but unsure about whether it’s safe to include caffeinated drinks to help boost you? You may have heard that it may not be great, but what actually are the facts?

Do you know how much is too much, and are you having too much? Should you cut it out all together?

How much is too much?

It is recommended that 200mg or less of caffeine per day may significantly reduce the risk of adverse birth and pregnancy outcomes associated with caffeine intake.

This table will help you to work out how you might add up to your 200g. We’re certainly not recommending the energy or soft drinks lol, but some of these might sneak into your day without you realising.

Dose

  Amount of caffeine

1 teaspoonful of instant coffee

  60mg

1 cup (200ml)

  100mg

1 shot espresso

  90mg

1 black tea teabag

  50mg

1 green tea teabag

  30mg

Energy drinks

  110mg

Cola soft drinks  

  40mg

60g milk or dark chocolate

  30-40mg

 

What could go wrong?

Several studies that suggest that caffeine consumption during pregnancy may cause foetal growth restrictions, which are known to have detrimental impacts on foetal development.

One recent review depicts that caffeine intake during pregnancy may increase the baby’s risk of having a low birth weight. Authors commented that low birth weight infants may experience excess growth during infancy, childhood obesity and chronic disease later in life.

What did Margaret do?

Many women actually develop an aversion to coffee and even tea during pregnancy, but Margaret was not one of those. We were able to help with supporting her to cut down on her 4+ cups of coffee each day by providing alternative ideas that fitted with her tastes and habits. She was down to two or less within a week of her visit. Margaret was pleasantly surprised how good decaffeinated coffee tasted nowadays as she used to think it was nasty.

What could you drink instead?

An easy swap for coffee is decaf coffee and just swapping to tea may also be enough for you. You may find some herbal teas are quite tasty, and if you’re suffering with morning sickness many find the lemon and ginger flavoured one can make a big difference. Of course, there’s always water and carbonated water, and if you want some flavour why not try the cold water tea bags which are caffeine free. Milk-based drinks and even the nut-milks can be a good option too. If these ideas don’t appeal to you, check with your dietitian for more ideas.

How are you managing?

Are you having more than your two cups of coffee or three to four cups of tea? What are you substituting the extra ones for?

Call us to chat on 0249710770, remembering that we can arrange TeleHealth consults if you're too busy or live too far away. Accredited Practising Dietitian Sally Marchini at Marchini Nutrition is one of the specialist dietitians from the Australia-wide network Nutrition Plus who offer more than just nutrition advice - they offer experience, problem solving, understanding and most importantly compassion to assist you on your health journey in preconception, pregnancy, postnatally and for specific health concerns. Sally can be contacted via her website www.marchininutrition.com, the Nutrition Plus website www.nutritionplus.com.au, by telephone on 02-4971-0770, or by email at sally@marchininutrition.com

References:

(1) Adherence to the Caffeine Intake Guideline during Pregnancy and Birth Outcomes: A Prospective Cohort Study, by Amy Peacock et al., Nutrients 2018, 10(3), 319; ttps://doi.org/10.3390/nu10030319

(2) Maternal caffeine intake during pregnancy and childhood growth and overweight: results from a large Norwegian prospective observational cohort study, by Eleni Papadopoulou et al., BMJ Open 2018;8:e018895. doi: 10.1136/bmjopen-2017-018895

By websitebuilder June 13, 2019

by Sally Marchini Accredited Practising Dietitian at Marchini Nutrition, Swansea

The colder months of winter can often cause our immune system to falter, putting us at risk of catching viruses such as the common cold. What we choose to eat during this period, especially if we’re pregnant, can make a big difference.

As well as the ‘usuals’ that we know contain the vitamins that keep us well such as fresh fruit and vegetables, an important consideration is our gut microbiome.

That’s the trillions of bacteria that live in our large intestine. It’s known that if we have sufficient numbers of the ‘good’ bacteria in our gut microbiome that they work hard to help keep us well. The way that we can ensure that they stay well is to feed them the food they like to eat. Fortunately for us in this colder weather, it’s many of the foods that we want to eat for comfort anyway that also prove to be so nutritious for our bub and its future health.

By websitebuilder June 10, 2019

It is important during pregnancy to eat well and takes care of your health. This will ensure the baby has the best chance of a healthy life. A woman's body goes through many changes during pregnancy and different body shapes will be affected by pregnancy in different ways.

About one third of women start their pregnancy overweight and this can cause problems for both the mother and the baby. If you can, plan for your pregnancy. It is best to start pregnancy within the healthy weight range.

Aim to monitor your weight gain throughout your pregnancy by weighing yourself every couple of weeks.

By websitebuilder June 10, 2019

All women who are pregnant without complications should be encouraged to participate in aerobic and strength-conditioning exercises as part of a healthy lifestyle during their pregnancy. A reasonable goal should be to maintain a good fitness level throughout pregnancy without trying to reach peak fitness.

It is important to stay well hydrated, wear comfortable and non-restrictive clothing (such as a correctly fitted bra and appropriate footwear) and where possible, avoid excessive over-heating.

Exercise during pregnancy offers many physical and emotional benefits. Physical activity may also help manage some symptoms of pregnancy and make you feel better, knowing you’re doing something good for yourself and your baby.

By websitebuilder April 19, 2019

Getting the cold or flu when you are pregnant can affect your unborn baby. If you are considering pregnancy or are already pregnant, it is highly recommended that you have the flu vaccination to help protect you and your baby.

By websitebuilder April 8, 2019
Dr Mary Norris from Newcastle Obstetrics & Ultrasound for Women is a specialist Obstetrician and Gynaecologist bringing over 30 years of multidisciplinary experience in women's health to Newcastle, Lake Macquarie and the Hunter Valley.
By websitebuilder March 19, 2019
Congratulations you are pregnant!

This can be a very exciting and overwhelming time of your life, filled with many, many questions. Take a deep breath, below we have compiled a list of useful questions that you can ask your obstetrician or midwife during your first prenatal visit to help reassure you and give you peace of mind during your wonderful journey.

It is important that you feel well-informed about your antenatal care and have accurate expectations about what will happen when you go into labour. The first prenatal visit usually happens between weeks 8 and 10, but it’s a good idea to let your provider know as soon as you find out you are pregnant.

Here are some useful questions you can ask during your first prenatal visit:
By websitebuilder March 19, 2019
Dr Mary Norris of Newcastle Obstetrics & Ultrasound spends much of her time advising women on how to optimise their health before, during, and after pregnancy to prevent low birth weight and other problems.
By websitebuilder January 8, 2019
In my last blog for Newcastle Obstetricswe discussed the importance of omega-3 intake for mothers for the mental outcomes of our babies. In staying with the omega-3 focus it’s also important to include enough if you’re at risk of pre-term birth.
By websitebuilder December 11, 2018

Drinking enough water is a necessity in order to stay healthy and ensure that your body functions smoothly. The importance of drinking water increases further if you are an expectant mother.

When you're pregnant, you need more water than the average person in order to form amniotic fluid, produce extra blood, build new tissue, carry nutrients, enhance digestion, and flush out wastes and toxins.


How much is enough?

Since you need more water during pregnancy, how much is enough? It’s recommended that you drink 8-12 glasses of water a day, or 2.3 litres. If your trips to the bathroom are frequent and your urine is pale or colourless, you're drinking is on track.


Could you be dehydrated?

Signs of dehydration to watch out for:

  • Overheating
  • Headaches/sluggishness
  • Dark or concentrated urine

 

Benefits of keeping well hydrated when pregnant

Especially during hot summer months, as a mum to be you will want to make sure you stay adequately hydrated. Here are just some of the benefits of staying hydrated during your pregnancy:

  • Decreases constipation/haemorrhoids
  • Reduces swelling
  • Prevents fatigue, headaches and overheating
  • Softens skin
  • Increases energy
  • Keeps you cooler
  • Decreases risk of urinary tract infections
  • Decreases risk of preterm labour and preterm birth

 

Having a hard time keeping hydrated? Follow these easy tips:

  • Add fruits such as lemons, limes, and frozen raspberries to your water.
  • Avoid caffeine.
  • Increase your fruit and vegetable intake (they have water, too!).
  • Milk, juice, sparkling water, tea, and soups all count as water or fluid intake.
  • Listen to your body; drink enough fluids that you rarely feel thirsty.
  • Drink enough fluids that your urine is and colourless or light yellow.
  • Stay out of the heat. Exercise indoors or early or late in the day.
  • Increase your fluid intake when you increase your activity level.

 

Dehydration can lead to serious complications including; low amniotic fluid, kidney stones, swelling and urinary tract infections, which can lead to birth defects, preterm labour and preterm birth. It is therefore very important to keep well hydrated and please see your doctor if you have any concerns.

The team at Newcastle Obstetrics & Ultrasound for Women are here to support you during your pregnancy, call 4947 4903.

More Posts
Share by: