For those who don’t like needles, the bad news is that you’ll need quite a few blood tests during your antenatal care, but the good news is, they are quick and painless and essential in finding out if anything is wrong during your pregnancy.

Pregancy tests
Most women discover they are pregnant by using home pregnancy tests – which are so accurate that there is no need to have any further testing to prove you are pregnant. However, if you do suspect you are pregnant and want further proof, or you are bleeding during pregnancy and want to establish if the pregnancy is viable, it is recommended that you have a blood test, which can be carried out by your GP. The earliest time that a blood test can be taken is eight days after conception or about one week before your next period is due.

As soon as the baby implants itself in your uterus the HCG hormone (Human Chorionic Gonadotrophin – the hormone that starts to be released after conception), enters your bloodstream. The HCG levels peak to their highest levels between eight and eleven weeks of pregnancy. They then level out slowly lowering at twelve weeks and again at sixteen weeks. (Some experts believe that it is the HCG levels that are responsible for morning sickness in pregnancy and could explain why morning sickness starts to subside at around 12 weeks of pregnancy).

Low HCG levels
Low HCG levels can indicate that the pregnancy is in the very early stages. The level of HCG is less important than how much it is rising every few days. If your HCG levels continue to rise the pregnancy is progressing normally. The best way to confirm a pregnancy this way is to test every few days to see if the levels are rising. Home pregnancy tests test your urine in the same way, so if you get a very faint line on your pregnancy test, wait three days and test again. If the HCG levels start to lower in the first twelve weeks of pregnancy it is fairly indicative that the pregnancy will miscarry.

High HCG levels
High HCG levels during the first twelve weeks of pregnancy can indicate a multiple pregnancy, or that the pregnancy is more advanced than originally thought.

Booking-in visit
During your first booking-in visit, with either your GP or at an antenatal clinic, you will be required to have some blood taken out. This is so your blood can be tested for a variety of things including:

Your blood group (In case you need a blood transfusion at any point during pregnancy or birth)

Whether you are Rhesus positive or negative (If you are Rhesus negative and your baby is positive, your boy may treat your baby as in ‘invader’ and it will produce antibodies to try to destroy your baby’s red blood cells. This can be combated by having injections during your pregnancy called Anti-D injections to stop your body producing anti-bodies.


All blood tests are optional, but if you agree, further tests will be taken to test you for:

HIV and AIDS
All pregnant women in the UK are offered an HIV test because HIV can be easily passed from mother to baby in the womb. Pregnant women who are HIV positive can be trated during pregnancy to help reduce the risk of their babies becoming infected.

Other Infections
Your immunity to German Measles (Rubella)
Syphillis or Hepatitis B
Both of these infections can be harmful to an unborn baby so it is important to test for these during pregnancy.

Sickle Cell Diseases

Your haemoglobin level
You will be offered a blood test during your pregnancy to test your iron levels to see if you are anaemic. Symptoms of anaemia include excessive fatigue so mention to your midwife if you feel unwell.

Nuchal Translucency Test
A fairly recent addition to the range of antenatal tests is the so-called nuchal translucency test, that takes place around 10-14 weeks of pregnancy and which combines a blood test with a complex ultrasound scan to establish what the risk of your baby having Down’s Syndrome is.

Down’s syndrome affects about 1 in every 1000 babies and is a genetic condition caused when a baby is born with an extra chromosome. Chromosomes are tiny particles in our bodies that carry the ‘blueprint’ for all the characteristics we inherit from our parents. There are 23 pairs of chromosomes in each cell, so 46 altogether and we inherit one half of each pair from our fathers and the other half of the pair from our mothers.

There are several factors that help to assess the risk of a baby having Down’s Syndrome and make up what is known as the Nuchal Translucency Test.The baby’s heart rate is monitored (as babies with a high heart rate are more likely to have Down’s Syndrome), the mother’s age is taken into account, the mother’s blood is taken and a detailed, high-resolution scan of the baby is taken.

Last Modified: 16/12/2008