Information For Raised BMI In Pregnancy

  • Reference Number: HEY-130/2016
  • Departments: Maternity Services

Information For Raised BMI In Pregnancy

This leaflet has been produced to give you general information about the effects a raised body mass index (BMI) can have on your pregnancy and in labour. It will explain what you can do to reduce your risk and improve your health by having a healthy lifestyle.

Most of your questions should be answered by this leaflet.  It is not intended to replace the discussion between you and your midwife or doctor, but can act as a starting point for discussion.   If after reading it you have any concerns or require further explanation, please discuss this with a member of the healthcare team caring for you.

What is a raised BMI?

Your BMI is calculated by dividing your weight (in kilograms) by your height (in metres) squared.

If your BMI is… You are…
Under 18.5 Underweight
Between 18.5 and 24.9 A healthy weight
Between 25 and 29.9 Overweight
30 or more Obese

Early in pregnancy you will have had your BMI measured. If it is 30 or more, you have a higher risk of complications for you and your baby.

In pregnancy

Being overweight increases the risk of:

  • High blood pressure and pre-eclampsia.
  • Developing diabetes.
  • Developing a blood clot (thrombosis) in your legs or lungs .
  • Early miscarriage.
  • Having a baby who is too big (macrosomia).
  • Labour being induced.

In labour

Being overweight:

  • Increases the chance of labour progressing slowly resulting in a longer labour.
  • Makes it more likely that assistance will be required to help deliver the baby, for example; ventouse (a suction cap attached to baby’s head) forceps or emergency caesarean delivery.
  • Increases the risk of infection.
  • Increases the risk of heavy bleeding.
  • Increases the risk of the shoulders getting stuck at the birth (shoulder dystocia).
  • Increases the risk of stillbirth.

If you decide to have an epidural for pain relief, it might be difficult and take longer to insert.

After baby is born

A baby is also more likely to be overweight and develop diabetes in later life. You may have an increased risk of developing an infection.

What can I do to help?

Simple things really can make all the difference.

  • Check the portion size of your meals and snacks and how often you eat.
  • Do not ‘eat for two’.
  • Eat a low-fat diet.
  • Eat as little as possible of the following: fried food, drinks and sweets/biscuits high in added sugars, and other foods high in fat and sugar.
  • Eat fibre-rich foods such as oats, beans, lentils, grains, seeds, fruit and vegetables as well as wholegrain bread, brown rice and pasta.
  • Eat at least five portions of a variety of fruit and vegetables each day.
  • Choosing wholegrain where possible.
  • Make activities such as walking, cycling, swimming, low impact aerobics and gardening part of your daily life.
  • Take the stairs instead of the lift or go for a walk at lunchtime.
  • Do not sit for long periods like watching television or at a computer.

Exercise will not harm you or your unborn baby but, if you are new to exercise you should begin with 15 minutes of continuous exercise, three times per week, increasing gradually to 30 minute sessions every day.

You can join groups for extra help and support:

Us Mums Hull

From aqua aerobics to Zumba –

Enable HULL

A family weight management service –


Antenatal and parenting classes –


A great start for babies and young children –

Helpful websites

Contact details

Should you require further advice on the issues contained in this leaflet, please do not hesitate to contact the Healthy Lifestyles Midwife on telephone number (01482) 607838.

General Advice and Consent

Most of your questions should have been answered by this leaflet, but remember that this is only a starting point for discussion with the healthcare team.

Consent to treatment

Before any doctor, nurse or therapist examines or treats you, they must seek your consent or permission. In order to make a decision, you need to have information from health professionals about the treatment or investigation which is being offered to you. You should always ask them more questions if you do not understand or if you want more information.

The information you receive should be about your condition, the alternatives available to you, and whether it carries risks as well as the benefits. What is important is that your consent is genuine or valid. That means:

  • you must be able to give your consent
  • you must be given enough information to enable you to make a decision
  • you must be acting under your own free will and not under the strong influence of another person

Information about you

We collect and use your information to provide you with care and treatment. As part of your care, information about you will be shared between members of a healthcare team, some of whom you may not meet. Your information may also be used to help train staff, to check the quality of our care, to manage and plan the health service, and to help with research. Wherever possible we use anonymous data.

We may pass on relevant information to other health organisations that provide you with care. All information is treated as strictly confidential and is not given to anyone who does not need it. If you have any concerns please ask your doctor, or the person caring for you.

Under the General Data Protection Regulation and the Data Protection Act 2018 we are responsible for maintaining the confidentiality of any information we hold about you. For further information visit the following page: Confidential Information about You.

If you or your carer needs information about your health and wellbeing and about your care and treatment in a different format, such as large print, braille or audio, due to disability, impairment or sensory loss, please advise a member of staff and this can be arranged.

Your newborn baby’s NHS number

An NHS number is allocated to everyone whose birth is registered with a Registrar of Births and Deaths in England and Wales. You already have an NHS number and your baby will be assigned an NHS number soon after birth. Your NHS number is unique to you and provides a reliable means of linking you to the medical and administrative information we hold about you. NHS numbers are allocated on a random basis and, in themeselves, provide no information about the people to whom they relate.