General advice for you

Body mass index or BMI is calculated by your weight to height ratio and is a practical estimation, used by health professionals, of weight range.

At your booking visit with the midwife, your height and weight will be recorded and your BMI will be calculated.

Approximately 1 in 3 women start pregnancy with a BMI greater than 25kg/m2 and are considered overweight. Most women who are overweight have a straightforward pregnancy and birth and deliver healthy babies. However research shows that women with a raised BMI of more than 30kg/m2 at the start of pregnancy are at slightly increased risk of complications during pregnancy and labour and the higher your BMI, the greater the risk of complications.

One of the aims of care during pregnancy is to identify those women who are at increased risk, in order to offer the best care throughout their pregnancy, to suit their individual needs and reduce the risks where possible.

BMI Classifications
You have a normal healthy range if your BMI is between 18.5 and 24.9. Between 25.0 and 29.9 is classed as overweight and 30 and over is classed as obese. Before you are pregnant you can work out your BMI using this calculator (but once you're pregnant it may not be accurate.)

Pregnancy risks associated with a raised BMI
A raised BMI >30kg/m2 increases the risk of the following:

• diabetes
• raised blood pressure
• blood clots
• less accurate ultrasound scans

Risks during labour and giving birth associated with a raised BMI

It is worth remembering that most women have straightforward births. However, we know that women who have a high BMI have more chance of having:

• monitoring difficulties 
• restricted mobilisation
• difficulty carrying out procedures
• increased risk of bleeding 
• difficulties with epidural/spinal analgesia
• bigger babies
• assisted delivery 

Because of these increased risks, it is recommended that if you have a BMI of 35kg/m2 or above, you have your baby in hospital on the delivery unit and are not suitable for the xx.

If your BMI is between 30 and 34.9 and you would like to use the xx, please discuss this with your community midwife.

Key messages

• the majority of overweight women have a straightforward pregnancy and birth
• enjoy a normal healthy diet and keep your weight gain to a minimum
• keep active and take regular, moderate intensity exercise
• take a high dose folic acid supplement of 5mg (milligrams) daily for the first 12 weeks of pregnancy to reduce the risk of neural tube defects
• take 10 micrograms of Vitamin D throughout pregnancy and during breastfeeding
• choose the most appropriate place to give birth
• women with a high BMI are at a higher risk of complications during pregnancy and labour
• following delivery mobilise as soon as possible especially if you have a caesarean section
• breastfeeding your baby can aid weight loss and is recommended to prevent the risk of obesity for the baby is later life
• reducing your BMI by 5 will reduce your chances of gestational diabetes in your next pregnancy by 80%

Being underweight and pregnant
If you have a low BMI speak to a midwife or GP about how to build yourself up gradually over the coming months. Follow their advice to eat a variety of healthy, nutritious foods, so your baby will get the calories and essential vitamins and nutrients he or she needs to develop well.

You may be more likely to have a premature or low-birth-weight baby if your BMI is low. Babies who are born early and small sometimes need extra care when they are born.

Whenever we cut ourselves, our blood hardens and a clot forms. This process is called blood clotting or coagulation.

Sometimes a clot of blood can occur within a vein, forming a ‘plug’ that can interrupt the normal flow of blood through the blood vessels. A deep vein thrombosis (DVT) is a blood clot in one of the deep veins, usually in the vein that runs through the muscles of the calf and thigh.

Pulmonary embolism (PE) occurs if a clot from a deep vein (usually in the leg) detaches itself and travels to the lungs. Sudden death will occur if the clot is large enough to stop blood flow through the heart and lungs.

DVT and PE together are known as venous thromboembolism (VTE). It is a serious condition which may cause severe pain, swelling, skin changes, shortness of breath and sudden collapse.

Anyone can develop a blood clot. However, women are more at risk during and following birth. This is due to an increase in blood volume, an increase in clotting factors in the blood, the effect of pregnancy hormones and the weight of a heavy uterus on the veins that drain the blood out the legs. Other risk factors include:    

• Smoking
• Age over 35
• Obesity – BMI over 30kg/m2
• Previous history of VTE

It is a recommendation from the National Institute of Health and Care Excellence (NICE) and the Royal College of Obstetricians and Gynaecologists (RCOG) that all women in pregnancy have a risk assessment performed in early pregnancy to establish their risk of developing a DVT or PE. This is because prevention of a DVT is crucial in reducing deaths from PE in pregnancy.

An antenatal assessment will be carried out at your first booking visit and is based on a scoring system. If your score is high risk you will be referred to the obstetric haematology clinic. Your GP will also be informed and will prescribe antenatal VTE thromboprophylaxis (a preventative medicine) with an anticoagulant (anti-clotting) drug.

If you need to be admitted to hospital during your pregnancy, a further VTE assessment will be carried out by a midwife and if necessary the medication will be prescribed for you on the ward by a doctor.

Other recommended treatments:

• wearing anticoagulation compression stockings. These are made of elastic fibres that squeeze the legs and promote healthy blood flow
• hydration – drink plenty of water
• stop or reduce smoking
• lose weight – keep active during pregnancy and after birth

Sexual health and relationships are as much a part of a healthy, balanced lifestyle as eating the right food or taking sufficient exercise.

It's perfectly safe to have sex during pregnancy. Your partner's penis can't penetrate beyond your vagina, and the baby cannot tell what's going on. It is normal for your sex drive to change during pregnancy, though. Don't worry about this, but do talk about it with your partner. 

Later in pregnancy, an orgasm or even sex itself can set off contractions (known as Braxton Hicks contractions). If this happens, you'll feel the muscles of your womb (uterus) go hard. This is perfectly normal and there's no need for alarm. If it feels uncomfortable, try your relaxation techniques or just lie quietly until the contractions pass.

When to avoid sex in pregnancy  
Your midwife or doctor will probably advise you to avoid sex if you've had any heavy bleeding in pregnancy, since sex may increase the risk of further bleeding if the placenta is low or there is a haematoma (a collection of blood).

You'll also be advised to avoid sex if your waters have broken (rupture of membranes) as this can increase the risk of infection. If you're unsure, ask your midwife or doctor.

Some couples find having sex very enjoyable during pregnancy, while others simply feel that they don't want to have sex. You can find other ways of being loving or making love. The most important thing is to talk about your feelings with each other.

Information syndicated from NHS Choices

If you are planning to travel abroad while pregnant, please discuss your plan with your midwife or doctor.

They can advise you about vaccinations and travel insurance and travel by air. Long-haul air travel is associated with an increase risk of VTE or whether or not there is an additional risk during pregnancy is unclear.

For most people, wearing compression stockings is effective for reducing the risk of VTE.

On other websites:

• Royal College of Obstetricians and Gynaecologists (RCOG): Air travel and pregnancy

Generally women who are pregnant or breastfeeding are advised not to take medication that can be brought from a shop without first consulting with their midwife or a pharmacist. All prescribed medication will be provided by a doctor, such as your GP or obstetrician, after confirming it is safe to take. Please make sure you tell your dentist that you are pregnant or breastfeeding before treatment.