The first trimester overview

What to expect during the first trimester of pregnancy

Your first trimester is from the day of conception (or the last day of the most recent period) to week 12 of the pregnancy. Your body starts to change rapidly as it prepares to have a baby. Your hormones are likely to change every organ and system in your body. At times, it might feel like your body is out of your control as symptoms begin to trigger in the first few weeks of pregnancy, potentially bringing with them fatigue, headaches, morning sickness and constipation.

Your uterus changes to support the growth of a foetus and the growth of the placenta as your body starts to increase blood flow, oxygen and nutrient supply to the developing foetus.

Your heart rate will also increase in order to aid in the development of the baby. With these changes, your doctor may recommend that you take supplements containing folic acid which help prevent birth defects such as brain disorders or issues with the baby’s spinal cord. It is important to remember that the first trimester is the most important for the baby’s development. Your baby is likely to develop all of its organs at the end of month three, thus making this period a crucial step for the baby’s growth.

It is advised that you stick to a healthy diet advised by your doctor. Do not smoke cigarettes or drink any alcohol, these substances are harmful to the developing baby.

First trimester tests

Your first test during this trimester is likely to be an at-home pregnancy test which tells you if you are pregnant or not. If you are, you will consult with your doctor, he/she will order a blood test to confirm your pregnancy.

Once pregnancy is confirmed, you will schedule a prenatal visit. During this visit your doctor will chat to you about your medical history, genetic issues or any other risk factors you may have that could put the baby at risk. He/she will also conduct the following during this visit:

A physical Examination

Your doctor may conduct the following during a physical examination:

• A pelvic exam
• A pap smear (if you haven't had one recently)
• Breast exam
• Blood pressure check
• Weight check 
• Ultrasound: Your doctor may perform an ultrasound scan to check the baby’s health and heartbeat.  Your baby's heartbeat will generally be visible as 6 weeks. 

Blood tests

• A blood type test (ABO Blood Group Test) and Rh factor (if you have Rh negative blood you may be asked to do a follow-up antibody screen test later in pregnancy. This is done because if you are Rh negative and your baby has Rh positive blood, this can cause an issue in a subsequent pregnancy and will be managed during delivery and thereafter).
• Iron levels
• Blood glucose to check for diabetes
• An STD test for HIV, Hepatitis B and syphilis
• Rubella (German measles) - most women have immunity after childhood vaccinations but some do not carry that into adulthood and this disease can cause serious birth defects.

Urine tests

You may be asked to submit a urine sample to test for:

• Protein
• Sugar

First trimester risks

Your risk of a miscarriage is at its highest in the first trimester for a number of reasons, and oftentimes the exact cause cannot be identified but chromosomal abnormalities are usually the most common reason for spontaneous abortion (miscarriage).   

Your doctor may advise you to avoid caffeine, shellfish and deli meat as these can contain harmful bacteria to the baby. It is also vital that you keep your doctor informed about all changes your body is going through, specifically ones that you feel may be abnormal.

Your doctor is likely to advise that you wait until you are in your second trimester to tell people you are pregnant, with the first trimester being the riskiest for the baby’s survival.

The first trimester gives you the chance to think about topics such as breastfeeding, parental classes and learning more about childbirth.

First trimester emotional and physical changes

Your first change that you will notice is that you will miss your period. There are however other changes that are also likely to occur, although these will differ from woman to woman:

• Swollen and tender breasts
• Morning sickness
• Fatigue
• Food cravings and aversions
• Headaches
• Heartburn
• Weight loss or weight gain
• Frequent urination
• Mood swings
• Constipation

First trimester routine changes

As your body starts to change and adapt to the baby inside of it, you may also deem it necessary to change your daily routine. You might find it better to go to bed earlier, change your diet, and eat smaller, more frequent meals. Most of the symptoms you are experiencing are likely to go away or become less intense as your pregnancy progresses. Every woman’s experience of pregnancy is different, your symptoms and reaction to it may be different to another woman’s.

First trimester baby growth at four weeks

At week four your baby is starting to grow and develop in the following ways:

• The heart has started to form
• The baby is about 0.6cm long
• The baby has started to grow arm and legs buds
• The spinal cord and brain have begun to form (the nervous system)

First trimester baby growth at eight weeks

At eight weeks, your baby begins to develop from an embryo to a foetus, which means the following has begun:

• The major organs have started to form
• The heart has started to beat
• The buds of the arms and legs are now growing longer
• The baby’s face has started to form features
• The fingers and toes have started to grow
• Your baby is now nearly 2.5cm long
• The sexual organs have started to grow
• The umbilical cord is now visible

First trimester baby growth at twelve weeks

The first trimester ends around week 12, at this time your baby is starting to develop and grow the following:

• The muscles and nerves start to work together – the baby is now able to form a fist.
• The external sex organs have formed and you can tell what sex the baby is (if you want to know 😉)
• The eyelids will now close in order to allow the eyes to develop and be protected
• They will only open again in the 28^th week
• The baby is about 7.6cm long