First Trimester

The first trimester of pregnancy can be a mix of emotions, from excitement to anxiety and even a little discomfort.

Every pregnancy is unique, yet there are many themes that are common to most pregnancies in the first trimester.

Developmental changes – Weeks 0 to 12

During the first 12 weeks, your baby will develop from a tiny embryo into a fully formed fetus, about the size of a lime. Whilst your baby will be moving regularly by this time, he or she is still too small for you to feel any movements.

Some typical changes you may notice during these first 12 weeks include:

  • Breast enlargement and tenderness
  • Increased need to urinate
  • Mood swings and feeling teary
  • Tiredness
  • Constipation
  • Morning sickness
  • Food cravings and aversions

Tips for nausea and vomiting

Nausea, often called ‘morning sickness’, is one of the most common symptoms of pregnancy. Possible causes of morning sickness are thought to include changes in hormone levels, blood pressure and carbohydrate metabolism.

Some tips that can help manage symptoms include:

  • Drink small amounts frequently over the day – water, as well as other fluids such as lemonade, diluted juice or cordial and ginger tea can help.
  • Eat little and often – sometimes dry crackers or plain biscuits first thing in the morning can help.
  • Eat a healthy, low GI snack before bed – for example, fruit with low fat yoghurt and nuts as this will help sustain energy levels until the morning.
  • Try acupressure bands worn on the wrist, this helps relieve symptoms in some women.
  • Avoid missing meals, as this can make nausea worse.

Morning sickness doesn’t typically pose any risk for your unborn baby. However, in some cases of prolonged and severe vomiting (a condition known as hyperemesis gravidarum) medical intervention may be necessary.


A healthy, balanced diet is essential from the beginning of your pregnancy. Although you won’t require any additional calories in your first trimester, you will require additional vitamins and minerals.

Healthy eating during your pregnancy  provides a good overview of what you should be eating, as well as what to avoid for optimal health during your pregnancy.

Avoid alcohol and smoking prior to and when you become pregnant.

  • Smoking and drinking alcohol can have serious and adverse pregnancy outcomes.
  • There are no safe levels of alcohol consumption in pregnancy.

Therefore it is recommended that you don’t drink alcohol or smoke if you are planning to become pregnant, or are pregnant.

Caffeine consumption should not exceed 300mg per day, which is about 3-4 cups of brewed coffee.


The National Health and Medical Research Council recommend taking folic acid and iodine in pregnancy. Folic acid is the synthetic form of folate – a B vitamin and it helps prevent your baby from a condition called spina bifida (a type of neural tube defect, NTD).

  • It is recommended you take a supplement containing at least 400 microgram of folic acid for a minimum of one month prior to conceiving, and for the first three months of pregnancy.
  • If there is an increased risk of an NTD such as:
    • A family history of neural tube defect, or a previous pregnancy resulting in an NTD.
    • If you are taking certain anti-epileptic medication or suffer from certain gastrointestinal condition that can cause poor gut absorption.
    • If you have a BMI greater than 30.
    • If you have diabetes prior to pregnancy.

You may require additional folic acid; Dr Hong or your GP will discuss your individual medical history with you at your consultation.

Iodine is a mineral essential for brain development and growth.

  • It is recommended to start a 150 microgram of iodine supplement when you start trying to get pregnant, or as soon as possible after finding out you are pregnant.
  • Women with pre-existing thyroid condition should discuss their condition with Dr Hong or their GP prior to taking an iodine supplement.

For some women, taking a pregnancy multivitamin is helpful, although it is recommended you discuss your personal nutritional needs with your doctor before commencing any supplements.

Exercise & weight

Exercise is important during pregnancy. It helps reduce anxiety and stress, prepares your body for labour and can help you manage your pregnancy weight.

It is recommended that pregnant women aim for low impact, moderate-intensity exercise (such as walking or swimming) of approximately 30 minutes duration on most days of the week.

Tests and scans you can expect in your first trimester:

  • hCG test – is a blood or urine test, which will detect or measure the amount of human chorionic gonadotrophin (hCG), a hormone that is produced when you are pregnant. The blood test is more sensitive than the urine test and can help your doctor confirm your pregnancy.
  • Dating scan – is an ultrasound to determine your due date if you are unsure when your last period was or you have irregular periods.
  • Combined First Trimester Screening (CFTS) – this test involves both a nuchal translucency scan and a blood test.
    • The nuchal translucency scan is an ultrasound scan conducted between 11 to 13 weeks + 6 days of pregnancy and it measures the fold of skin at the back of your baby’s neck – called the nuchal fold.
    • The blood test, testing for a number of biomarkers, is done between 9 to 13 weeks + 6 days of pregnancy.
    • The blood test, along with the mother’s age and measurements of the nuchal fold all provide an assessment of risk of the baby having a condition called Down syndrome (or Trisomy 21).
    • Other genetic disorders including Trisomy 13 (Patau syndrome) and Trisomy 18 (Edwards syndrome) are also screened for in the CFTS.
  • Non-Invasive Prenatal Testing (NIPT) – also called cell-free DNA (cfDNA) testing is a maternal blood test, which can screen the baby’s DNA (via the mother’s blood) to assess the risk of Down syndrome and other genetic disorders in the baby.
    • The blood test can be done from 10 weeks of pregnancy.
    • This test is more accurate than the CFTS, however it is not funded and it cost more than the CFTS.
    • If your result comes back abnormal, you may require a further procedure called an amniocentesis (where a sample amniotic fluid is collected) or chorionic villus sampling (where a sample of cells are taken from the placenta) to confirm a genetic disorder.

What is an amniocentesis?

An amniocentesis is a medical procedure where a needle is inserted into a woman’s abdomen under the guidance of an ultrasound. A sample (1-2 tablespoons) of amniotic fluid is collected to test for chromosomal conditions such as Down syndrome.

  • There is a very small risk of miscarriage with an amniocentesis (less than 0.5%).
  • The needle will feel similar to that of a regular blood test, and some women experience mild cramping or period-like pain during the procedure.
  • An amniocentesis can be performed from 15 weeks of pregnancy.

What is CVS (Chorionic Villus Sampling)?

Similar to an amniocentesis, a CVS also involves a needle being inserted into a woman’s abdomen or vagina under ultrasound guidance, to sample cells from the placenta (chorion). The sample is used to test for chromosomal conditions or inherited diseases.

  • A CVS can be performed from 11 weeks of pregnancy.
  • There is a 1% risk of miscarriage with a CVS.

It is important to remember that most pregnancies are normal and healthy. The routine scans and test you encounter during pregnancy are to ensure optimal health for both you and your baby.

If you do have any concerns or questions regarding scans and testing during your pregnancy, it is recommended you always speak to Dr Hong.

Read on to find out what happens in your Second Trimester

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