In a nutshell

Gestational diabetes (GD) is a type of diabetes that can affect some women during pregnancy. It tends to appear in later pregnancy and usually disappears after your baby is born. You can generally just treat it with changes in the way you eat and exercise but some women with GD may need medication.


Most women with GD have healthy babies and have no further complications after the birth. But it is worth knowing that having GD can raise your risk of developing type 2 diabetes later in life.

What is gestational diabetes exactly?

Gestational diabetes is caused by having too much glucose (sugar) in your blood (see more about this in So, what causes gestational diabetes?, below). It affects about 1 in 6 of us and a warning sign can be sugar in your wee – but you'd then need a blood test to confirm GD for sure.

Finding out that you have gestational diabetes can be a shock but, "the good news is that, with expert care from medical staff, your pregnancy and birth should both go smoothly," says midwife Anne Richley,

And that certainly the experience shared by many of the mums on our forum: "I had gestational diabetes and my LO is fine!" says wannababy. "She arrived by herself and I had a normal birth and it went away after she arrived."

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How do they test for it?

One of the reasons we all have to pee in those pots before an antenatal appointment is so that our midwife can do dip test to see if there’s sugar in our wee. If there is, that may be a sign that you have GD.

To find out if it is GD, you’ll have to have a Glucose Tolerance Test. This is usually done when you're between 24 and 28 weeks pregnant – unless you’ve had gestational diabetes before, when you’ll be offered it at around 16 weeks.

It involves a morning blood test, taken after you've fasted (this is important), then another blood test, taken 2 hours after you've drunk a high-sugar syrupy drink. The 2 blood tests are then compared to see how your body reacts to the glucose. The results usually take a few days to come back.

And the test doesn't always indicate GD, as MFMer Queenemsfound out: "They found sugar in my urine. I went for the test and everything was fine: and it turned out I was eating too much fruit and drinking too many smoothies!"

How to understand your test results

You will be diagnosed with gestational diabetes if:

  • Your fasting plasma glucose level (the level of glucose in your 1st blood test, taken before you'd eaten anything) is 5.6 mmol/litre (millimoles per litre) or above OR
  • Your 2-hour plasma glucose level (the level of glucose in your 2nd blood test, taken 2 hours after you'd had the sugary drink) is 7.8 mmol/L or above.

Occasionally, you may be told you’re ‘borderline GD'. This means that your results are close to, but not over, the official figures. If this is the case for you, your midwife may well want to repeat the GTT later on in your pregnancy, and she will almost definitely want to give you some diet advice.

"I had borderline diabetes in my last pregnancy," says Sazzle33. "It really wasn't that bad, once the initial shock had worn off, and I got plenty of advice and support.”

What's the treatment for GD?

In most cases, the main treatment for gestational diabetes is aiming to control your blood-sugar levels by eating a healthy diet and exercising. Some pregnant women may need to take medication or inject insulin, as well.

You may be asked to check your blood-sugar levels a couple of times a day by using a blood glucose meter at home. It's a simple procedure: you just prick your finger, put a little drop of blood on a test strip and then into blood glucose meter, and you’ll get a measure of the amount of sugar in your blood.

Knowing this information can help you eat the right foods at the right time and avoid becoming hypoglycemic (when your blood-sugar levels are dipping too low) or hyperglycemic (when your blood sugar are spiking too high). If you’re a bit of a chocoholic or you are a bit of a fizzy-drinks-chugger, you’ll definitely be advised to curb your habit.

Will I get help with changing my diet?

“If you are diagnosed with GD, your antenatal team will support you to improve your diet," says Dr Kaye. "Basically, the main advice is to avoid skipping meals, to eat lots of vegetables and fruit and to limit sugar and sugary food."

Your midwife will probably suggest you substitute some foods for foods with a lower GI (glycaemic index), which means they'll release glucose more slowly into your bloodstream. Good low-GI choices include porridge oats (instead of cereal), wholewheat bread (instead of white), sweet potatoes (instead of regular spuds) and brown rice (instead of white).

Will GD affect my baby? Will I have a huge baby?

Most women who have gestational diabetes go on to have a healthy baby. However, you’ll definitely be monitored more closely and you’ll have extra ultrasound scans to make sure your baby doing OK.

But yes: GD can increase your chances of having a baby who weighs more than 4.5kg (10lbs). Having a baby as big as this (or bigger) does slightly raise your risk of complications at birth and, very rarely, it can be a cause of stillbirth.

For this reason, your midwife may pay particular attention to the size of your bump – even though it's not always the best indicator of the size of your baby: "I was told I was having a big baby so they did a growth scan and I had a GTT test. It turns out that she was measuring bang on the dates!” MJ1986andEsmae

wannababy didn't have a 'whopper' either: "She was 8lb 7oz, so not silly big, and she was born at 39 weeks."

What's this about birth complications?

A large baby may increase your risk of needing a Caesarean section but that really doesn't mean, says Dr Kaye, that all women with GD will have one. The same applies to the increased risk of going into premature labour.

If you have GD and there's concern about your baby's size, you may well be induced before your pregnancy reaches full-term.

During labour, you and your baby will be monitored closely. It’s important that your blood-sugar levels are stable to help prevent your baby developing problems after birth.

Unfortunately, all this means that it’s unlikely that you’ll be able to have a home birth, or a water birth.

Will my baby be diabetic?

Straight after the birth, your baby may have low blood-sugar and may need to be monitored for a while until his or her body gets used to making the right amount of insulin.

This could mean your baby is taken to a neonatal unit or, if he was born prematurely (before 37 weeks), a special care baby unit.

It's also true that, if you have GD, your baby is more likely to develop type 2 diabetes, or become obese, later in life. But it's not a given: taking normal, sensible steps to feed your baby healthily (including breastfeeding, if you can) and help him or her lead an active life can do a lot to help prevent this.

What about me? Will I always be diabetic now?

No. Usually, GD goes away after birth but you’ll be monitored before you leave hospital and checked again at your 6-week postnatal appointment.

"The majority of women with gestational diabetes will recover after pregnancy," said Dr Kaye, "although you're quite likely to get it again if you fall pregnant again: approximately 2 out of 3 women who have previously had GD will have it again in a future pregnancy."

(Not so) freaky fact: your partner may be affected, too

There is now some evidence that, if you have GD, your partner may develop diabetes (type 2), too.

"The incidence of diabetes is 33% greater in men whose partner has gestational diabetes, compared with men whose partners did not have gestational diabetes," says the lead author of a recent Canadian study at the Research Institute of the McGill University Health Centre."

It's not quite a bizarre as it sounds. As the researchers point out, couples who share a house often share the same eating and exercise habits, so if your lifestyle is not as healthy as it could be, your partner's probably isn't, either.

So, what causes gestational diabetes?

When you're pregnant, your body naturally becomes insulin-resistant – meaning your cells respond less well to insulin (a hormone that absorbs glucose from your blood for your body to store or use for energy). Because of this, the level of glucose in your blood remains high – and that means you can pass on plenty of growth-promoting glucose to your baby through your placenta.

All this extra glucose in your blood means your body is going to need to produce more insulin to deal with it. But some of us either cannot produce enough extra insulin in pregnancy to transport the glucose our body needs into our cells, or our body cells simply become more resistant to insulin than is usual in pregnancy. This is what's known as gestational diabetes.

Some of us will develop GD for no apparent cause. However, there’s a much greater chance of developing GD, says Dr Philippa Kaye, if you’re overweight or obese. "Obesity is associated with insulin resistance," she says.

Indeed, one US study of 14,000 women found that women with a BMI above 33 were over 4 times more likely to develop gestational diabetes than women who had a normal BMI before pregnancy.

And if you smoke, have a poor diet and don’t take regular exercise, the chances of you developing the condition are higher still, according to the same study.

There are other risk factors for GD, too – and not all of them are lifestyle-related. They include:

  • You've had a baby previously weighing 4.5kg (10lbs) or more at birth
  • You had gestational diabetes in an earlier pregnancy
  • You have a close family history of diabetes
  • You have South Asian, Africa-American, or Middle Eastern family origins
  • You’ve had a previous stillbirth
  • You gained a large amount of weight between pregnancies
  • You have a short gap between your pregnancies

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