Gestational diabetes: screening, care and birth

Pregnancy changes how the body handles glucose. The NHS explains that gestational diabetes happens when your body cannot produce enough insulin, the hormone that controls blood sugar, to meet the extra demand. It can appear at any stage but is more common in the second or third trimester.

It is different from type 1 or type 2 diabetes that was already present before pregnancy. Diabetes UK describes it as affecting women who do not already have another type of diabetes, with extra NHS care to keep both mother and baby well.

Anyone can develop it. The NHS lists these factors that raise the chance, and says that if any apply you should be offered screening.

• Being over 40.

• A body mass index above 30.

• A previous baby weighing 4.5kg (10lb) or more at birth.

• Gestational diabetes in an earlier pregnancy.

• A parent or sibling with diabetes.

• South Asian, Black, African-Caribbean or Middle Eastern family origin, even if you were born in the UK.

• Having had a gastric bypass or other weight-loss surgery.

Most women feel well. If blood sugar becomes high, the NHS says you may notice increased thirst, needing to pee more often, a dry mouth, tiredness, blurred eyesight, or genital itching or thrush. Several of these are common in any pregnancy, so they are not proof of the condition. Tell your midwife or doctor if you are worried.

At the booking appointment, around week 8 to 12, your midwife or doctor asks about risk factors. If you have one or more, you should be offered an oral glucose tolerance test. The NHS says it takes about 2 hours: a blood test in the morning after 8 to 10 hours without food, a glucose drink, two hours of resting, then a second blood sample.

Timing differs if you had gestational diabetes before. The NHS says you are offered an OGTT soon after booking, then another at 24 to 28 weeks if the first is normal. Some women are instead offered finger-prick self-testing. NICE sets the diagnostic cut-offs, and says a joint diabetes and antenatal clinic review should be offered within a week of diagnosis.

You are given a kit to check your own blood sugar. The NHS says you are usually advised to test before breakfast and one hour after each meal. A dietitian should be involved. Advice includes regular meals, slow-release starchy foods such as wholewheat pasta and pulses, plenty of fruit and vegetables, and swapping sugary snacks and drinks for alternatives. You do not need a completely sugar-free diet.

Activity lowers blood glucose. NICE suggests regular exercise, for example a 30-minute walk after a meal. The NHS mentions gentle options such as walking, swimming and prenatal yoga, and asks you to tell your midwife or doctor before starting something new.

If levels are still unstable after 1 to 2 weeks of changes, or are very high at diagnosis, the NHS says medicine is added. This is usually metformin tablets, occasionally glibenclamide, or insulin by pen. Metformin side effects include sickness and diarrhoea. Insulin can cause low blood sugar, with shakiness, sweating, hunger or poor concentration. NICE advises immediate insulin if the fasting glucose is 7.0 or above at diagnosis.

The NHS says extra appointments are offered: a scan at around 18 to 20 weeks, growth and fluid scans at 28, 32 and 36 weeks, and regular checks from week 38. Poorly controlled sugar can lead to a larger baby, extra amniotic fluid, early birth, pre-eclampsia, newborn low blood sugar or jaundice, and rarely stillbirth. Most women have otherwise normal pregnancies.

NICE advises giving birth no later than 40 weeks plus 6 days, with induction or caesarean offered, and earlier birth considered if there are complications. Take your testing kit and medicines to hospital. Your sugar is checked hourly in labour, and insulin may be given by drip. The NHS says your baby will be fed within 30 minutes of birth where possible and have blood sugar checks from 2 to 4 hours.

Medicines are usually stopped after birth, and you are advised to keep checking sugar for a day or two. The NHS recommends a diabetes blood test 6 to 13 weeks later because a small number of women stay high, then yearly if normal. You are more likely to develop type 2 diabetes, so the NHS Diabetes Prevention Programme can help with diet, exercise and weight.

If you plan another pregnancy, ask your GP for a diabetes check first. Without diabetes, you will be offered early screening next time. Some research mentioned by the NHS suggests children of mothers with gestational diabetes may be more likely to develop diabetes or obesity later.

Contact your midwife or maternity unit the same day if your baby is moving less than usual, if you notice marked thirst with frequent urination that is getting worse, or if you feel unwell on insulin. Call 999 for collapse, confusion or unresponsiveness, which can be severe low blood sugar. NHS 111 can advise if you cannot reach your team.

Gestational diabetes is usually managed in a joint diabetes and antenatal clinic through NHS maternity services, including the extra scans and dietitian input described above. Private obstetric or diabetes consultations exist alongside this, but birth planning, monitoring and the postnatal diabetes test should still be coordinated with your maternity team and GP, so that no checks are missed.