Complications of gestational diabetes

Is my baby at risk of complications now I have gestational diabetes?

Gestational diabetes is a serious condition that can cause many complications. The advice given by your diabetes health care professionals should be taken seriously as uncontrolled or poorly controlled gestational diabetes can lead to severe complications. Having gestational diabetes itself automatically causes a higher risk of certain complications during pregnancy.

NOTE: The risk of complications is greatly reduced if gestational diabetes is diagnosed and managed properly throughout pregnancy

Sophie’s son, Freddie, read Sophie’s story here

Gestational diabetes just causes bigger babies – expelling the myth!

The most well-known complication and general cause of concern of gestational diabetes is a large baby.

When there is too much sugar in the mother’s bloodstream, this is passed through or fed to the baby. The baby then has to increase its own insulin production to help process the excess sugars. Insulin is a growth hormone and the result is that the baby grows excessively and for many the AC [abdominal circumference] increases. It is adipose tissue (subcutaneous fat) caused by the overproduction of insulin that causes the baby to grow big.

large growth

By controlling blood sugars with diet, exercise and some will also need meds/insulin, this helps the baby to regulate their insulin production to normal levels and the rate of growth of the baby’s AC slows whilst the rest of the baby’s growth catches up. This means that the baby returns to ‘normal’ or average growth size.

If blood sugar levels are controlled and managed well, babies are rarely born big, but they may suffer other complications which are related to diabetes in pregnancy.  

We often hear new members of our support group say that they are not worried as the baby isn’t measuring big, but monitoring for other complications which gestational diabetes can cause or be related to is extremely important.

Unfortunately, there are many more complications that can be related to gestational diabetes and poor glucose control than just a big baby.

If you have family and friends that are struggling to understand gestational diabetes, then you may want to refer them to this page and our page on gestational diabetes and the family to have a look.

Possible complications if blood glucose levels are not controlled or poorly controlled

If gestational diabetes is not managed properly or goes undetected/undiagnosed, it could cause a range of serious complications for both you and your baby:

  • Macrosomia – your baby being large for its gestational age i.e. weighing more than 4kg (8.8lbs) This is the most commonly known complication of gestational diabetes.  Macrosomia increases the need for induced labour or a caesarean birth, and may lead to birth problems such as shoulder dystocia (see below)
  • Shoulder dystocia Macrosomia can lead to a condition called shoulder dystocia. This is when your baby’s head passes through your vagina, but your baby’s shoulder gets stuck behind your pelvic bone. Shoulder dystocia can be dangerous, as your baby may not be able to breathe while they are stuck. It’s estimated to affect 1 in 200 births. Following shoulder dystocia deliveries, 20% of babies will suffer some sort of injury, either temporary or permanent. The most common of these injuries are damage to the brachial plexus nerves, fractured bones, contusions and lacerations, and birth asphyxia.
  • Premature birth (your baby being born before week 37 of the pregnancy) – This can lead to complications such as newborn jaundice or respiratory distress syndrome (RDS).
  • Health problems shortly after birth that require hospital care – such as newborn hypoglycaemia (low blood sugar) and/or newborn jaundice
  • Miscarriage – the loss of a pregnancy during the first 23 weeks
  • Stillbirth – the death of your baby around the time of the birth

Other complications related to gestational diabetes

  • Placenta insufficiency – premature ageing of the placenta, also known as placenta deterioration, placenta dysfunction or placenta failure. A direct complication linked to gestational diabetes which causes abnormalities and complications in the placenta. For further information on placenta deterioration, read more here. NOTE: Consult your diabetes health care professionals should you start experiencing frequent, very low blood sugar levels and/or frequent hypos. It is important to get checked and monitored if a difference in baby’s movements are noticed; please call your maternity assessment unit immediately.
  • Polyhydramnios – Excessive amniotic fluid – detected by ultrasound. Polyhydramnios can be caused by polyuria (frequent urination) and lung liquid production. Detection of polyhydramnios can be the flagstone for gestational diabetes testing in mother’s who have not yet been diagnosed.
  • IUGR – Intrauterine growth restriction is a condition where a baby’s growth slows or ceases when it is in the uterus, also known as SGA or small for gestational age (under 10th centile for gestational age) – detected by ultrasound. A shock to many as it’s contradictory to the usual complication of macrosomic (large for gestational age) baby.
  • Pre eclampsia – Pre-eclampsia is a condition that affects some pregnant women, usually during the second half of pregnancy (from around 20 weeks) or soon after their baby is delivered. Early signs of pre-eclampsia include having high blood pressure (hypertension) and protein in your urine (proteinuria). It is unlikely you will notice these signs, but they should be picked up during your routine antenatal appointments. In some cases, further symptoms can develop, including:
    • swelling of the feet, ankles, face and hands caused by fluid retention (oedema)
    • severe headache
    • vision problems
    • pain just below the ribs

If you experience any of these symptoms of placenta deterioration or pre-eclampsia, then please seek medical advice immediately

*Please note: this is not an exhaustive list of possible complications related to gestational diabetes

The most common complications

Even in mothers who have maintained good control of blood sugar levels throughout pregnancy, the most common complications are:

Health problems shortly after birth that require hospital care

  • newborn hypoglycaemia (low blood sugar) and/or
  • newborn jaundice

The most commonly seen complications in gestational diabetes babies we’ve had in the Gestational Diabetes UK Facebook support group have been neonatal hypoglycaemia and neonatal jaundice.  Placenta deterioration, Polyhydramnios and IUGR have also been seen in the group a frequently and has led to mothers being induced or delivered earlier than previously planned.

Neonatal or newborn hypoglycaemia

Newborn babies of diabetic mothers when there has been poor diabetic control in pregnancy will often struggle with their own blood sugar levels after birth.  This is due to them overproducing their own insulin whilst growing in the uterus, in a way to help process the excess sugars passed from the mother’s bloodstream. These babies may have high insulin levels persisting in the first few days after birth which can result in hypoglycaemia. Babies of mothers who have had reasonably good blood glucose control may still suffer from low blood sugar levels after birth too.

Testing the newborn for hypoglycaemia

In the majority of hospitals, newborns born to diabetic mothers are monitored for hypoglycaemia.  Each hospital is different as to how they monitor blood sugar levels, but the procedure is the same.  A midwife or nurse will heel prick the baby to obtain enough blood to be tested on a blood glucose test monitor, the same as we use to monitor our own blood sugar levels throughout the pregnancy.  You may find watching this distressing as sometimes (but not always) babies may become distressed, screaming and crying once they have been pricked with the lancet.  You may notice that your baby’s foot looks blue or purple in colour following the testing too.  As much as this may seem terrible for your baby to go through, it is very important that levels are checked to make sure they are not suffering hypoglycaemia.

The number of tests and times taken can vary, but your hospital will have a policy which they will follow. The most commonly used test times are 3 tests, 3 hours apart either before or after feeding which must all be above a certain target.  Once again, different targets are used for this.  Some hospitals may have longer testing times such as 3 hourly for 24 hours and we have seen a couple of our Mums in the Facebook support group inform us that they do not test babies for hypoglycaemia in their hospital.  Our advice would be to enquire about this and raise concerns should you have any. NICE guidelines recommend in their ‘Preventing and assessing neonatal hypoglycaemia’ guideline that

1.5.7 All maternity units should have a written policy for the prevention, detection and management of hypoglycaemia in babies of women with diabetes. [2008]

BM record - complications of gestational diabetes baby


  1. Keep blood sugar levels within target and stabilised  – It is best try to keep your blood sugar levels within your targets and stabilised throughout your pregnancy, especially leading up to and during labour. Some mothers will be on a sliding scale insulin & glucose drip to control blood sugar levels during labour, but this may not be necessary if you gain good control over your levels.
  2. Skin to skin and 1st feed – Once baby is born, skin to skin is very important and initiating a first feed within the first 30 mins will aid good blood sugar levels in baby.
  3. Colostrum harvesting – Many mothers with gestational diabetes harvest colostrum before the birth of baby to be able to give the newborn top up feeds, should breast feeding be a problem, or to give additional top up feeds in between feeds as colostrum is the best thing to raise blood sugar levels.
Colostrum harvesting and feeding
newborn being fed colostrum via syringe

NICE guidelines regarding neonatal hypoglycaemia

Preventing and assessing neonatal hypoglycaemia 1.5.7 All maternity units should have a written policy for the prevention, detection and management of hypoglycaemia in babies of women with diabetes. [2008] 1.5.8 Test the blood glucose of babies of women with diabetes using a quality‑assured method validated for neonatal use (ward‑based glucose electrode or laboratory analysis). [2008] 1.5.9 Women with diabetes should feed their babies as soon as possible after birth (within 30 minutes) and then at frequent intervals (every 2–3 hours) until feeding maintains pre‑feed capillary plasma glucose levels at a minimum of 2.0 mmol/litre.[2008, amended 2015] 1.5.10 If capillary plasma glucose values are below 2.0 mmol/litre on 2 consecutive readings despite maximal support for feeding, if there are abnormal clinical signs or if the baby will not feed orally effectively, use additional measures such as tube feeding or intravenous dextrose. Only implement additional measures if one or more of these criteria are met. [2008, amended 2015]

1.5.11 Test blood glucose levels in babies of women with diabetes who present with clinical signs of hypoglycaemia, and treat those who are hypoglycaemic with intravenous dextrose as soon as possible. [2008, amended 2015]

Neonatal Jaundice

Jaundice causes yellowing of the skin and the whites of the eyes. Jaundice is one of the most common conditions that can affect newborn babies.

Treatment of jaundice

Frequent feeding and exposing the baby to natural light helps jaundice. Treatment is usually only recommended if tests show a baby has very high levels of bilirubin in their blood because there is a small risk in these cases that the bilirubin could pass to the brain and cause brain damage. The main treatment that can be carried out in the hospital to quickly reduce a baby’s bilirubin levels is phototherapy – a special type of light shines on the skin, which alters the bilirubin into a form that can be more easily broken down by the liver. Babies are put on a light bed also known as a ‘bili-bed’.   This can usually be done at your bedside so that your baby can stay with you, but in more severe cases or sometimes where mobile facilities are not available your baby may be moved to SCBU (Special Care Baby Unit) or NICU (Neonatal Intensive Care Unit) for more intensive phototherapy.

bili-bed phototherapy

In extremely severe cases, an exchange transfusion may be needed. This is a transfusion where small amounts of the baby’s blood are removed and replaced with blood from a matching donor. NICE guideline recommendations for neonatal jaundice

Intensive light therapy for gestational diabetes complications
Gemma’s baby receiving more intensive phototherapy

Breathing difficulties and RDS (respiratory distress syndrome)

If your baby is due to be delivered before 38 weeks gestation by induction or possibly later by elective caesarean section, then you may be advised to have steroid injections to mature your baby’s lungs which helps prevent breathing difficulties. Steroids cause high blood sugar levels and so some hospitals will admit you if you need steroid injections.  To help regulate blood sugar levels following steroid injections a sliding scale (insulin & glucose drip) may be used.  Some hospitals, however, will not admit you for steroid injections but will advise you to call in if your levels go over a certain level. This differs depending on the area and NHS Trust.

If you have high blood sugar levels following steroid injections then you should contact your diabetic team or Maternity Assessment Unit.  Drinking water helps to flush out excess sugars and walking helps to lower blood sugar levels, but this may not make as much of an impact as it usually does following steroids.  It is important to seek medical advice if your blood sugar levels remain high.

For more information on the sliding scale insulin and glucose drips, please see below.

Variable rate insulin infusion AKA Sliding scale (insulin & glucose)

A sliding scale is an IV drip with glucose and insulin (2 drips). It helps to stabilise blood glucose levels by adding glucose if your levels drop too low and adding insulin if your levels rise too high. They are commonly given to ladies who need steroid injections for inductions and planned c-sections before 38 weeks. Steroid injections are used for lung maturity as respiratory problems are at higher risk with premature babies, those delivered by CS and babies born to mothers with gestational diabetes and the injections can cause very high blood sugar levels. Not all hospitals admit or use a sliding scale whilst giving steroid injections.

variable rate insulin infusion (sliding scale, insulin & glucose drip)
sliding scale in hand

The other time sliding scales are used are during labour for some ladies with diabetes. Some hospitals will use them as per their Trust or hospital policy; diet, metformin or insulin control makes no difference. Other hospitals will only use them for insulin controlled mothers and some will only use them if they see blood sugar levels drop or spike to a certain level. If you have stable well-controlled blood sugar levels throughout pregnancy and labour, then a sliding scale is not necessary.

Caesarean section due to gestational diabetes

Gestational diabetes in itself as a condition is not a reason to be advised to have a caesarean section. However planned caesarean may be offered to you, or advised if your baby is showing very large for gestational age following growth scans, where the diagnosis has been very late in the pregnancy or where poor glucose control has been an issue.

NICE guidelines for caesarean section.

Induction of labour

For many ladies with gestational diabetes, due to many of the complications mentioned above, we may be advised to be induced due to medical reasons. According to the current NICE guidelines induction (or elective caesarean section) should only be considered before 40+6 weeks for women with gestational diabetes if there are maternal or fetal complications. For more information on Induction of labour please read more here.

Post birth diabetes testing

Gestational diabetes increases your risk of developing type 2 diabetes after pregnancy. Statistics from Diabetes UK state that there is a sevenfold increased risk in women with gestational diabetes developing type 2 diabetes in later life. NICE states that up to 50% of women diagnosed with gestational diabetes develop type 2 diabetes within 5 years of birth.

It is recommended that you should have a fasting glucose blood test at 6 weeks post-partum OR an HbA1c blood test after 13 weeks post-partum to check that you are clear of diabetes.  It is no longer recommended that a repeat GTT is performed to check that the diabetes is clear (NICE guidelines Feb 2015).  Many ladies have concerns over taking a fasting glucose test whilst breastfeeding or attending for blood tests whilst their newborn is still very young.  If you have these concerns then you may want to opt for an HbA1c blood test after 13 weeks post-partum. You do not need to fast and it is one simple blood test that can be taken at your local GP surgery.

It is important to be tested annually for diabetes following gestational diabetes with an HbA1c blood test. Type 2 diabetes is when your body either does not produce enough insulin, or the body’s cells do not react to the insulin causing insulin resistance.

Knowing the risk factor of being diagnosed with type 2 diabetes later in life is higher, it is advisable to look and dietary and lifestyle choices that could impact and lessen your chances of being diagnosed.

We very rarely see ladies being diagnosed as type 1 diabetics following gestational diabetes, but gestational diabetes may be the flagstone for testing for type 1 diabetes.

For further information on post-birth diabetes testing, please read more here.

Complications later in life for your baby

A baby born to a mother who had gestational diabetes has a sixfold increase in the risk of developing diabetes and has a higher risk of obesity (having a body mass index of more than 30) later in life.

Future pregnancies

After having gestational diabetes, you are at increased risk of having gestational diabetes in any future pregnancies. It’s very important to speak to your GP if you are planning another pregnancy or when you fall pregnant. They may arrange for you to monitor your own blood glucose from the early stages.  Some hospitals will assume that you have gestational diabetes in a subsequent pregnancy and will treat you as such from the start.  Other hospitals will get you to perform an earlier GTT (glucose tolerance test), this is commonly around 16 weeks. Following a negative GTT, repeat GTT is usually offered.

Research articles

Effect of Treatment of Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis

Treating GDM reduces risk for many important adverse pregnancy outcomes and its association with any harm seems unlikely.

Effect of Treatment of Gestational Diabetes Mellitus on Pregnancy Outcomes

Treatment of gestational diabetes reduces serious perinatal morbidity and may also improve the woman’s health-related quality of life.

Gestational Diabetes Mellitus 

Diabetes and Pregnancy 

Foetal and neonatal complications in gestational diabetes: perinatal mortality, congenital malformations, macrosomia, shoulder dystocia, birth injuries, neonatal complications

WHO recommendations for induction of labour

The Placenta and Gestational Diabetes Mellitus

The Human Placenta in Gestational Diabetes Mellitus – The insulin and cytokine network

Delivery timing and cesarean delivery risk in women with mild gestational diabetes mellitus

Consequences of gestational and pregestational diabetes on placental function and birth weight

Vascular dysfunction in the diabetic placenta: causes and consequences

Polyhydramnios: Causes, Diagnosis and Therapy

Perinatal outcomes of idiopathic polyhydramnios

Induction versus expectant monitoring for intrauterine growth restriction at term: randomised equivalence trial (DIGITAT)

Care of the infant of the diabetic mother 

Neonatal complications in infants born to diabetic mothers 

Perinatal complications in women with gestational diabetes mellitus

Hypoglycaemia of the newborn 

Intensive glycemic control in diabetic pregnancy with intrauterine growth restriction is detrimental to fetus 

Effect of timing of umbilical cord clamping of term infants on maternal and neonatal outcomes 

Optimal timing for clamping the umbilical cord after birth

A systematic review and meta-analysis of a brief delay in clamping the umbilical cord of preterm infants

Stillbirth in the Pregnancy Complicated by Diabetes

Effect of screening and management of diabetes during pregnancy on stillbirths



Women with pre-gestational (type I and type II) diabetes mellitus (DM) have an increased risk of second and third trimester stillbirth compared to women without diabetes. Even with modern obstetric care and diabetes management, stillbirth rates in women with type II DM have been reported to be 2.5-fold higher than non-diabetic women [34]. On a population-basis, women with gestational diabetes (GDM) have similar stillbirth rates as a normal population. However, some women with “GDM” diagnosed during pregnancy actually entered the pregnancy with undiagnosed type II DM, and have the same risk of fetal loss as women with type II DM. Thus, when there is clinical evidence that a woman with GDM may have undiagnosed type II DM, she should be considered to be at increased risk of stillbirth. Examples of women who may have undiagnosed type II DM include those with high fasting glucose values, random or postprandial glucose values >200 mg/dl, history of GDM in prior pregnancies (particularly when no glucose testing was done in the interval between pregnancies), or diagnosis of GDM early in pregnancy.

The factors that account for the increased risk of late pregnancy fetal loss in diabetic women are not fully understood. Although an increased likelihood of fetal anomalies contributes to the increased risk, the stillbirth rate for non-anomalous fetuses is also higher in diabetic women than in non-diabetics. Co-morbid conditions, such as obesity and hypertension, are also more common in women with DM. Fetal growth abnormalities, both growth restriction and excessive growth, are increased in women with DM, and both increase the risk of stillbirth. The link between excessive fetal growth and stillbirth likely involves maternal hyperglycemia leading to fetal hyperglycemia, which in turn triggers excess fetal insulin production to keep fetal plasma glucose levels in the physiologic range. In the fetus, insulin spurs fetal growth, which may result in metabolic acidosis if excessive, and if the placental oxygen supply is insufficient. The endpoint of this process may be a stillbirth.

The exact glycemic threshold that places a diabetic pregnancy at increased risk for stillbirth is not well characterized. However, it has been shown that identifying and treating diabetes lowers the stillbirth rate in these women [35].

Identification and treatment of women with hyperglycaemia diagnosed during pregnancy can significantly reduce perinatal mortality rates

We conclude that identification and treatment of women with gestational diabetes can reduce perinatal mortality rates.