13 Weeks

What’s happening this week

You...

• may find any sickness starts to get better, as the placenta takes over producing the pregnancy hormones
• may feel your clothes getting tighter around your waistline

Your baby..

• is growing well, but tiny – about 7.5 cm long
• looks just like a baby now, though he or she is not much bigger than a egg
• can kick his legs, turn his head and even swallow
• is developing the swirls of fingerprints on his skin.

The hormone changes of the early weeks begin to settle and your chances of miscarriage are now much lower. This week we explain what the usual blood tests are for.

Understanding blood tests

The blood that is taken at your booking-in visit is tested for:

• blood group and Rhesus factor
• blood sugar
• haemoglobin level
• syphilis
• hepatitis B
• rubella (German measles) immunity (if you are not immune, you are advised to avoid contact with anyone who may have rubella; you’ll be offered an immunisation injection after your baby is born).

All this information is held in your file – you should be told the results even if everything’s fine. All your results should be written in your records which you may be carrying. You may also be tested for sickle cell disease.

This primarily affect women from African, West Indian, Asian and, to a lesser degree, some women from Mediterranean backgrounds. You may be tested for thalassaemia, which mainly affects women from Mediterranean and Asian backgrounds. This is because these diseases could be passed on to your children. If you are tested for these diseases, you’ll be told the result and will be given a card showing whether you have them or not. If you are found to have them, you will be referred for specialist counselling; your partner will also be offered screening for the disease.

Rhesus status

During pregnancy, your blood will be tested for the presence of a particular protein called the Rhesus factor. If you have the Rhesus factor attached to your red blood cells you’re described as Rh-positive; if you don’t, you’re described as Rh-negative. Most women in NZ are Rh-positive.

It is important to know if you are rhesus negative and if the father the baby is positive. Then there’s a chance your baby will have inherited the Rhesus factor from the father. Because you don’t have it, your immune system could react to your baby’s blood as if it were a ‘foreign invader’. This could cause anaemia – and possibly jaundice – in the baby. But problems are very rare these days because you can be given treatments to prevent them happening.

If you are Rh-negative, you will be told, and you’ll need extra care. You may be given an injection of rhesus-immune globulin (Anti-D) after the birth of the baby. You may also have some extra blood tests to see if you have developed any Rhesus antibodies.

This rarely happens, but if it does, you will be carefully monitored. If you have a ‘sensitising’ event, such as an accident, car crash, fall, amniocentesis or CVS, you may need an injection of Anti-D immunoglobulin. This will coat any of the baby’s cells that may be in your bloodstream and destroy these ‘invaders’ before your immune system responds to them.

Not enough iron?

Many women need extra iron when they’re pregnant. A lack of iron can make you feel tired and breathless. If your iron levels are low, your LMC will prescribe iron tablets, but there are simple ways to help keep your levels up.

1. Eat meat or fish with other iron-rich foods. Baked potatoes with beef chilli or a chicken sandwich make good meals


2. Drink a glass of orange juice with your meal; vitamin C helps you absorb iron.


3. Drink less tea; the tannin in tea reduces the amount of iron you can take in.


4. Treat yourself to the occasional bar of chocolate! Dark chocolate especially is high in iron.


5. Add dried fruit like raisins and apricots to your bowl of breakfast cereals.

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