Gestational Diabetes: Causes and Symptoms

Leonie Millard
Leonie Millard

Published: February 16th, 2023

6 min

What is gestational diabetes?

Gestational diabetes is high blood sugar that develops during pregnancy. It is more common in the 2nd and 3rd trimester of pregnancy. Blood sugar levels can shoot up even without a history of diabetes. Some people are at greater risk than others , and screening is offered for the following:

  • aged over 40

  • a BMI above 30

  • previous baby that weighed 4.5kg (10lb) or more at birth

  • gestational diabetes in a previous pregnancy

  • 1 of your parents or siblings has diabetes

  • you are of south Asian, Black, African-Caribbean or Middle Eastern origin.

If you have any of the risk factors you should be offered screening between 24 and 28 weeks. It may be earlier if you have had it before. This is a simple blood test, known as a glucose tolerance test (OGTT). The National Institute for Health and Care Excellence (NICE) introduced guidelines in 2015.

What are the symptoms of gestational diabetes?

You can often be asymptomatic, but the following may indicate hyperglycaemia ( high blood sugar):

  • increased thirst

  • a dry mouth

  • fatigue

  • blurred eyesight

  • genital itching or thrush

  • increased need to urinate.

Who is at risk of developing gestational diabetes?

It is estimated to affect around 4%-5% of pregnant women in the UK and has become more common as rates of obesity increase.

What problems can gestational diabetes cause?

  • A large baby. This can often be spotted on growth charts at scans, hence the need for more frequent monitoring; This may lead to earlier induction of labour or caesarean section.

  • polyhydramnios - too much amniotic fluid

  • premature birth - before the 37th week of pregnancy

  • pre-eclampsia - a condition that causes high blood pressure during pregnancy and can lead to pregnancy complications if not treated

  • your baby developing low blood sugar or jaundice after birth

  • the loss of your baby (stillbirth).

How well the blood sugar is controlled may determine when the infant is born, but it is usually before 41 weeks.

How can gestational diabetes be managed?

Through diet as far as possible, but also exercise medication and insulin.

What additional monitoring should be provided for gestational diabetes?

Extra antenatal appointments to include:

  • an ultrasound scan at around week 18 to 20 of your pregnancy to check your baby for abnormalities

  • ultrasound scans at week 28, 32 and 36 - to monitor your baby's growth and the amount of amniotic fluid, plus regular checks from week 38 onwards.

The International Journal of obstetrics and gynaecology published a study online in March 2019 which found that women who have gestational diabetes but go undiagnosed are four times more likely to experience stillbirth than those without the condition. The study was funded by charities Action Medical Research, Cure Kids, Sands and Tommy's and involved pregnant women at 41 maternity units across the UK.


For further information please contact Leonie Millard

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