Antenatal Care

Keeping your baby healthy during pregnancy

Your first appointment will normally take place around 8-10 weeks’ gestation.

At this initial visit, your Obstetrician will spend time getting to know you and your expectations, so please bring a list of any questions, concerns or special requests. Dr Chettle likes to allow plenty of time for this first visit, so you can expect this consultation to take about 45 minutes.

During this visit, you will be asked for details about your medical and pregnancy history and an examination will be performed. This usually involves taking your blood pressure and examining your lungs, thyroid, heart, and abdomen. If you have not had a recent pap-smear or breast examination then this may form part of the examination. In addition, an ultrasound of your growing baby will be performed.

For this visit, you will need to bring with you;

  • The referral letter from your general practitioner doctor.
  • Your Medicare and private health fund details.
  • Any relevant past medical and surgical information (including previous pregnancy outcomes).
  • Any pathology or diagnostic imaging results/reports that may be relevant.

During your pregnancy, you will have approximately 10-12 appointments, these will include;

  • First visit 8-10 weeks
  • Every 4 weeks until the 28th week of pregnancy
  • Then every 2 weeks until 36 weeks
  • Then once a week until delivery
  • We will also see you 6-8 weeks after childbirth for a post-natal visit & “well woman check-up”

Dr Chettle may need to see you more or less frequently based on individual circumstances. Please feel free to bring along your partner or a support person to your antenatal visits.

What does antenatal care comprise?

Antenatal care includes regular medical visits, screening tests, and diagnostic tests to help assess you and your baby’s health status throughout the pregnancy. Routine visits are scheduled so that any problems present may be recognised and treated well in advance. These visits also educate you on handling various aspects of your pregnancy. At these appointments, Dr Chettle will also discuss healthy eating, physical activity, necessary screening tests and what to expect during labour and delivery.

Your care will always be individualised to your pregnancy. No two pregnancies are the same – even for the one woman!

Routine antenatal investigations time line (for normal risk women)

Pre-Pregnancy  Before you fall pregnant it’s a good idea to visit your GP and ensure your vaccinations are up to date. At this appointment, your GP may also carry out investigations including;

  • Full Blood Count (FBC)
  • Blood Group and Antibodies
  • Serology – Hepatitis B & C, HIV, Syphilis, Rubella titre
  • Urine test
  • ** Increased maternal risk factors may lead to other tests including but not limited to – Varicella, Chlamydia/Gonorrhoea screen, HbA1c

6-7 weeks  Early dating ultrasound – i.e. when you are 2-3 weeks “late” for your period

10 weeks+  Non-invasive Prenatal Testing (NIPT) if desired

11-13+6 weeks  Combined first trimester screen – this test combines a nuchal translucency ultrasound scan along with specific blood tests

18-22 weeks  Morphology Scan (ultrasound)

26-28 weeks  Oral Glucose Tolerance test (OGTT) + repeat FBC/Group and antibodies +/- Iron studies (+ administration of Anti-D to Rhesus negative women)

36 weeks  FBC +/- Group and antibodies +/- Iron studies (+ administration of Anti-D to Rhesus negative women)


Below, we take an in depth look at the 3 types of testing you may have done during your pregnancy, these are;

  1. NIPT
  2. Combined first trimester screening
  3. Morphology scan


  1. NIPT

Non-invasive prenatal testing (NIPT) refers to testing of the fetal genome (DNA) through a sample of the mother’s blood. This test is non-invasive and poses no risk to the pregnancy. The major benefit of NIPT is a significant reduction in the need to perform invasive testing e.g. chorionic villous sampling (CVS) or amniocentesis.

NIPT is an advanced screening test for common chromosomal abnormalities. It is more accurate than other screening tests, such as the combined first trimester screen in predicting Down syndrome (trisomy 21), Edwards syndrome (trisomy 18) and Patau syndrome (trisomy 13). Sex chromosomal abnormalities, such as Turner syndrome (45,X) and Klinefelter syndrome (47,XXY), can also be detected, but with reduced accuracy.

NIPT is not 100% accurate and should not be regarded as a diagnostic test. All abnormal results should be confirmed by invasive testing before making significant clinical decisions, e.g. termination of pregnancy. An unexpected normal result, e.g. in a fetus with malformations, may also warrant invasive testing.

NIPT is highly accurate, detecting more than 99% of fetuses with trisomy 21, and more than 95% of fetuses with trisomy 18, trisomy 13 or abnormalities of sex chromosomes. These are much better detection rates than we observe with conventional first trimester screenin. NIPT is also much better at identifying fetuses with normal chromosomes than conventional first trimester screening; more than 99.9% of normal fetuses are categorised correctly by NIPT, versus 95% by conventional first trimester screening.

NIPT does not detect every genetic abnormality in the fetus, or every developmental problem that might occur during pregnancy. NIPT will not detect less common or “atypical” chromosomal abnormalities which constitute approx. 20% of all chromosomal abnormalities. NIPT will also not detect any neural tube defects (e.g. spina bifida), placental abnormalities or risk of fetal growth restriction. Hence why NIPT does not replace the nuchal/combined first trimester screen.

  1. Combined First-Trimester Screening

Combined first-trimester screening is done to detect the risk of abnormalities such as Down’s syndrome and trisomy 13 and 18. The tests will be carried out between 11 and 14 weeks gestation. The screening includes blood tests and an ultrasound. The ultrasound is often referred to as the nuchal translucency (NT) ultrasound.  The ultrasound is used to measure the thickness of a skin fold at the back of the neck called the NT.

The baby’s length, NT and your age are combined to calculate your baby’s risk level of Down syndrome (Trisomy 21). A blood test measuring two hormones (PAPPA and HCG) is also taken. The results of these tests are used to predict the risk of abnormalities in the fetus. The detection rate is 85-90%. It is important to remember that not all babies with a chromosomal abnormality will be detected by this method as the detection rate is not 100% guaranteed using either technique.

If your first trimester screening tests are positive, your doctor may suggest further investigations with a maternal-fetal medicine (MFM) specialist. The ultrasound will also provide information about the development of the fetus along with a review of any sign of neural tube defects.

If the screening tests indicate a problem in the baby, further diagnostic tests such as detailed ultrasound, amniocentesis, and chorionic villus sampling and cordocentesis may be recommended to check whether the baby actually has a defect.  After the screening, if your baby is found to have an increased risk for developing a chromosomal abnormality or if a problem is detected with diagnostic testing, genetic counselling will support you with further decisions.

  1. Morphology Scan

Your 18 to 22 week ultrasound scan is also known as the morphology scan. This scan looks for abnormalities in your baby’s structural development and growth. It also checks the position of the placenta. It is not a screening test for chromosomal anomalies.

A morphology scan’s main purpose is to detect structural abnormalities.

The ultrasound scan is performed by a specially trained sonographer. At that time, and if there is a good visualisation of your baby, your sonographer may be able to tell you the sex of your baby – if you wish to know.

Although a number of birth defects can be identified by ultrasound, there are many that will not be detected. At 18 to 22 weeks the detection rates for structural anomalies is 40 to 70 per cent. It is important to remember that a normal ultrasound does not always mean your baby will be born without any abnormalities.

Generally the earliest time to look for birth defects is between 18 and 22 weeks of pregnancy however, some will not become evident until late in the pregnancy. Anatomic areas such as the heart, the face and the hands are difficult to assess and not all defects are detectable.

Other factors such as your weight, scars from a previous operation and the way your baby is positioned may limit the diagnostic ability of this test.




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