Antenatal checks and tests

During your pregnancy, you'll be offered a range of tests, including blood tests and ultrasound baby scans.

These are designed to:

• help make your pregnancy safer
• check and assess the development and wellbeing of you and your baby
• screen for particular conditions

You do not have to have any of the tests – it's your choice. However, it's important to understand the purpose of all tests so you can make an informed decision about whether to have them. You can discuss this with your maternity team.

Weight and height checks in pregnancy

You'll be weighed at your booking appointment, but you will not be weighed regularly during your pregnancy. Your height and weight are used to calculate your body mass index (BMI).

If you are overweight you have an increased risk of problems during pregnancy.

Find out more about being overweight when you get pregnant

You're likely to put on 10 to 12.5kg (22 to 28lb) in pregnancy after being 20 weeks pregnant. Much of the extra weight is because the baby is growing, but your body also stores fat for making breast milk after birth.

Talk to a GP or midwife if you are concerned about your weight.

It's important to have a healthy diet in pregnancy and do regular exercise during your pregnancy.

Antenatal urine tests

You'll be asked to give a urine sample at your antenatal appointments. Your urine is checked for several things, including protein.

If this is found in your urine, it may mean you have a urine infection. It may also be a sign of pre-eclampsia.

Blood pressure tests in pregnancy

Your blood pressure will be checked at every antenatal visit. A rise in blood pressure later in pregnancy could be a sign of pre-eclampsia.

It's very common for your blood pressure to be lower in the middle of your pregnancy than at other times. This is not a problem, but it may make you feel lightheaded if you get up quickly. Talk to your midwife if you're concerned about it.

Find out more about high blood pressure and pregnancy

Blood tests and scans in pregnancy

As part of your antenatal care, you'll be offered several blood tests and scans. Some are offered to everyone, while others are only offered if you might be at risk of a particular infection or condition.

All the tests are done to make your pregnancy safer or check that the baby is healthy, but you do not have to have them if you do not want to.

For more information visit our page about screening tests in pregnancy

Blood group and rhesus status

You will be offered a blood test to tell you whether you are blood group rhesus negative or rhesus positive. If you are rhesus negative you may need extra care to reduce the risk of rhesus disease.

Rhesus disease can happen if you are rhesus negative and pregnant and involves your body developing antibodies that attack the baby's blood cells. This can lead to anaemia and jaundice in the baby.

If you are rhesus negative, you may be offered injections during pregnancy to prevent you from producing these antibodies. This is safe for both mother and baby.

Iron deficiency anaemia

Iron deficiency anaemia makes you tired and less able to cope with loss of blood when you give birth.

You should be offered screening for iron deficiency anaemia at your booking appointment and at 28 weeks.

If tests show you have iron deficiency anaemia, you'll probably be offered iron and folic acid.

Gestational diabetes

You may be at higher risk of developing diabetes in pregnancy (gestational diabetes) if you:

• are overweight
• have had diabetes in pregnancy before
• have had a baby weighing 4.5kg (9.9lb) or more before
• have a close relative with diabetes
• have a south Asian, black or African Caribbean, or Middle Eastern family background

If you're considered to be at high risk for gestational diabetes, you may be offered a test called the OGTT (oral glucose tolerance test). This involves drinking a sugary drink and having blood tests. 

The OGTT is done when you're between 24 and 28 weeks pregnant. If you've had gestational diabetes before, you'll be offered:

• early self monitoring of blood glucose levels, or
• an OGTT earlier in pregnancy, soon after your booking visit, and another at 24 to 28 weeks if the first test is normal

Find out more about gestational diabetes