Gestational Diabetes and Birth

The date your pregnancy now has a limit on

Gestational diabetes changes the latest point at which you will be left to go into labour on your own.

NICE NG3, recommendation 1.4.4: "Advise women with gestational diabetes to give birth no later than 40 weeks plus 6 days. Offer elective birth by induced labour or (if indicated) by caesarean section to women who have not given birth by this time."

Recommendation 1.4.5 adds: "Consider elective birth before 40 weeks plus 6 days for women with gestational diabetes who have maternal or fetal complications."

It is worth knowing that this limit is specific to gestational diabetes. Women with type 1 or type 2 diabetes and no other complications are advised under recommendation 1.4.2 to have an elective birth "between 37 weeks and 38 weeks plus 6 days" — a full two to three weeks earlier. If you have been told your date is 38 weeks and you have gestational diabetes rather than pre-existing diabetes, that is worth asking about, because NG3 sets a different limit for each.

Vaginal birth is not ruled out

A diagnosis of gestational diabetes is not in itself a reason for a caesarean. NG3 recommendation 1.4.1 asks teams to discuss the timing and mode of birth with you during antenatal appointments, "especially during the third trimester", and recommendation 1.4.6 states that "diabetes should not be considered a contraindication to vaginal birth after a previous caesarean section".

Where a big baby is suspected, recommendation 1.4.7 asks that "for pregnant women with diabetes who have an ultrasound-diagnosed macrosomic fetus, explain the risks and benefits of vaginal birth, induction of labour and caesarean section". That is a conversation, not a decision handed to you.

The growth scans that feed into this conversation are set out in recommendation 1.3.34: ultrasound monitoring of fetal growth and amniotic fluid volume "every 4 weeks from 28 to 36 weeks". Ultrasound estimates of weight carry a wide margin of error at term, which is worth raising if a single scan is being used to argue for a particular mode of birth.

Where you are advised to give birth

NG3 recommendation 1.5.1 asks teams to "advise women with diabetes to give birth in hospitals where advanced neonatal resuscitation skills are available 24 hours a day". The RCOG's patient information similarly advises birth in a hospital with a consultant-led maternity unit and a neonatal unit.

This is the practical reason a planned home birth or a standalone midwifery unit is usually advised against with gestational diabetes. The concern is the baby's blood sugar and breathing in the first hours, not the labour itself.

What happens to your blood sugar during labour

Monitoring becomes hourly and the target range changes. NG3 recommendation 1.4.10: "Monitor capillary plasma glucose every hour during labour and birth for women with diabetes, and maintain it between 4 mmol/litre and 7 mmol/litre."

Recommendation 1.4.12 adds that intravenous dextrose and insulin infusion is used "during labour and birth for women with diabetes whose capillary plasma glucose is not maintained between 4 mmol/litre and 7 mmol/litre". Recommendation 1.4.11 considers that infusion from the onset of established labour specifically for women with type 1 diabetes.

Most women with diet-controlled gestational diabetes go through labour on hourly finger-prick checks and nothing more. If you are having a general anaesthetic, recommendation 1.4.9 asks for monitoring "every 30 minutes from induction of general anaesthesia until after the baby is born and the woman is fully conscious". Recommendation 1.4.8 offers an anaesthetic assessment in the third trimester where there are comorbidities such as obesity.

Your baby in the first hours

This is the part that surprises people most, and it is entirely routine. NG3 recommendation 1.5.3: "Carry out blood glucose testing routinely at 2 to 4 hours after birth in babies of women with diabetes."

Feeding is treated as the first-line prevention. Recommendation 1.5.9 asks that babies are fed "as soon as possible after birth (within 30 minutes) and then at frequent intervals (every 2 to 3 hours) until feeding maintains their pre-feed capillary plasma glucose levels at a minimum of 2.0 mmol/litre".

Recommendation 1.5.10 says additional measures such as tube feeding or intravenous dextrose are used only if "capillary plasma glucose values are below 2.0 mmol/litre on 2 consecutive readings despite maximal support for feeding", or there are abnormal clinical signs, or the baby will not feed effectively by mouth.

Recommendation 1.5.2 is the one to hold onto: "Babies of women with diabetes should stay with their mothers, unless there are complications or abnormal clinical signs that mean the baby needs to be admitted to intensive or special care." A blood sugar test is not an admission.

Before you go home

NG3 recommendation 1.5.6 says not to transfer babies of women with diabetes to community care until "they are at least 24 hours old and you are satisfied that the baby is maintaining blood glucose levels and is feeding well". Expect at least one night in hospital even after a straightforward birth.

For you, recommendation 1.6.3 is immediate: "Women who have been diagnosed with gestational diabetes should stop blood glucose-lowering therapy immediately after birth." Recommendation 1.6.8 adds that your blood glucose is tested before transfer to community care to exclude persisting hyperglycaemia.

What to have written down before you go in

Three things are worth having explicitly in your notes and in your own copy. First, your latest growth scan result and the plan that follows from it — NICE guideline NG3 recommendation 1.3.34 offers growth and amniotic fluid monitoring every four weeks from 28 to 36 weeks, so there should be a recent one.

Second, the agreed date. Recommendation 1.4.4 sets 40 weeks plus 6 days as the limit, but many women with gestational diabetes are offered birth earlier, and recommendation 1.4.5 allows that where there are maternal or fetal complications. If your date is earlier than 40+6, ask which complication it is based on.

Third, your medication plan for the day itself. Metformin and insulin regimens are altered around labour and stopped immediately afterwards under recommendation 1.6.3, and knowing what happens to yours saves a conversation at an unhelpful moment.

It is also worth asking about colostrum harvesting. Many units offer women with diabetes the option of expressing and freezing colostrum in the weeks before birth, so that a baby whose blood sugar is low has mother's milk available immediately rather than formula. It is not in NG3, so ask locally.