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A. BMI is your body mass index, which is a measure of your weight in relation to your height.
A. Your BMI will be calculated at your first antenatal booking appointment.
You may be weighed again later in your pregnancy.
A. Most women with a high BMI have a straightforward pregnancy and have healthy babies. However, being overweight or obese does increase the risk of complications for you and your baby. The higher your BMI, the greater the risks.
Your obstetrician will discuss with you any additional risks for you and your baby as well as how these can be reduced.
Thrombosis:
Thrombosis is a blood clot in your legs (venous thrombosis) or in your lungs (pulmonary embolism), which can be life-threatening. Pregnancy itself increases your risk of developing thrombosis. If you are overweight, the risk of developing thrombosis is further increased.
Your risk for thrombosis will be assessed at your first antenatal appointment and will be monitored during your pregnancy. You may be offered injections of a medication called low-molecular-weight heparin to reduce your risk of thrombosis. This is safe to take during pregnancy.
Gestational diabetes:
Diabetes that is first diagnosed in pregnancy is known as gestational diabetes.
If your BMI is 30 or above, you are three times more likely to develop gestational diabetes compared with women with a BMI under 25.
You will be offered a test for gestational diabetes between 24 and 28 weeks. If the test shows that you have gestational diabetes, you will need further testing and treatment.
High blood pressure and pre-eclampsia:
Being overweight increases your risk of developing high blood pressure and pre- eclampsia.
If you have a BMI of 30 or above, your risk of pre-eclampsia is 2–4 times higher compared with those with a BMI under 25.
Your blood pressure and urine will be monitored at each of your appointments. Your risk of pre-eclampsia may be further increased if:
If you have these or other risk factors, your obstetrician may recommend a low dose of aspirin to reduce the risk of you developing pre-eclampsia.
Mental health problems:
All pregnant women are asked some questions about their mental health at their first antenatal appointment. Being overweight slightly increases your risk of developing mental health problems in pregnancy and after birth.
Risks for your baby:
A. Healthy eating
A healthy diet will benefit both you and your baby during pregnancy and after birth. You may be referred to a dietician for specialist advice about healthy eating.
Trying to lose weight by dieting during pregnancy is not recommended. However, by making healthy changes to your diet, you may not gain any weight during pregnancy and you may even lose a small amount. This is not harmful.
Exercise
Physical activity will benefit both you and your baby. If you have not previously exercised routinely, you should begin with about 15 minutes of continuous exercise, three times per week, increasing gradually to 30-minute sessions every day. Some examples of healthy exercise include swimming, walking and pregnancy yoga.
An increased dose of folic acid
Folic acid helps to reduce the risk of your baby having a neural tube defect. If your BMI is 30 or above, a daily dose of 5 mg of folic acid is recommended. Ideally, you should start taking this a month before you conceive and continue to take it until you reach your 13th week of pregnancy. However, if you have not started taking it early, there is still a benefit from taking it when you find out that you are pregnant.
Labour and giving birth
There is an increased risk of complications during labour and birth, particularly if your BMI is 40 or more.
These complications include:
A. You may be offered a cannula (a fine plastic tube that is inserted into a vein to allow drugs and/or fluid to be given directly into your bloodstream) early in labour.
If you are overweight, it may be more difficult for your healthcare professional to do this, which may lead to a delay if it is not done until it is needed in an emergency situation.
Pain relief
All types of pain relief are available to you. However, having an epidural can be more difficult if you are overweight. You may be offered a discussion with an anaesthetist to talk about your choices for pain relief during labour.
Delivering the placenta
To reduce your risk of postpartum haemorrhage (heavy bleeding after childbirth), your obstetrician will recommend having an injection to help with the delivery of the placenta.
A. After giving birth, some of your risks continue. By working together with your obstetrician, you can minimise the risks in a number of ways, as discussed below.
Monitoring blood pressure
If you developed high blood pressure or pre-eclampsia during pregnancy, you are at increased risk of high blood pressure for a few weeks after the birth of your baby and this will therefore be monitored.
Prevention of thrombosis
You are at increased risk of thrombosis for a few weeks after the birth of your baby. Your risk will be reassessed after your baby is born. To reduce the risk of a blood clot developing after your baby is born:
Information and support about breastfeeding
How you choose to feed your baby is a very personal decision. There are many benefits of breastfeeding for you and your baby. It is possible to breastfeed whatever your weight.
Healthy eating and exercise
Continue to follow the advice on healthy eating and exercise. If you want to lose weight once you have had your baby, you can discuss this with your doctor.
Planning for a future pregnancy
If you have a BMI of 30 or above, whether you are planning your first pregnancy or are between pregnancies, it is advisable to lose weight. By losing weight you:
If you have fertility problems, it is also advisable to lose weight.
Your doctor can offer you advice and support to lose weight.
Crash dieting is not good for your health.
Remember that even a small weight loss can give you significant benefits.
You may be offered a referral to a dietician
Key points