Offspring of diabetic pregnancy: Short-term outcomes
Introduction
In spite of clinicians apparently appreciating the risks of maternal diabetes to the baby, babies of mothers with diabetes are still at increased risk compared to those of non-diabetic women.1 These babies are heavier and have a higher haematocrit,2 and are more likely to be hyperbilirubinaemic3 as well as hypocalcaemic and hypomagnesaemic.4, 5 They have a higher mortality rate, are more likely to be born prematurely, are at greater risk of developing respiratory distress, hypoxic ischaemia and are more likely to be separated from their mothers after birth.6, 7
This chapter considers the short-term outcomes for these infants. It discusses the incidence and management of diseases that may be due to the maternal condition, but does not deal with congenital malformations, which are considered in Chapter 4, or the complex issues of hypoglycaemia and blood glucose management, which are considered in detail in Chapters 7 and 9.
Section snippets
The incidence of morbidities and mortality for infants of diabetic mothers
In the 1990s, the increased morbidity and mortality of infants of diabetic mothers were clearly demonstrated by several separate regional studies in the UK: the perinatal mortality rate was increased between three- and tenfold, and congenital malformation rates were between four- and tenfold higher.6, 8, 9, 10, 11 Rudge et al.6 found that rates of spontaneous abortion, fetal and neonatal deaths were also more frequent among diabetic women.
Writing in 1998, Cordero et al. summarised the problems.
Respiratory distress syndrome (RDS)
Babies of mothers with diabetes are more likely to develop respiratory distress for two reasons. First, they are more likely to be delivered prematurely and are therefore at risk of developing straightforward surfactant-deficient RDS. For example, in the CEMACH study, more than a third of women with diabetes were delivered prematurely and 32% were delivered between 32 and 26 weeks' gestation. In part this was due to induced preterm delivery.1 Second, infants of diabetic mothers are more likely
Macrosomia
The generally accepted sequence of causation was proposed by Pedersen in 1949: glucose crosses from the maternal circulation to the fetus by facilitated diffusion across the placenta,26, 27, 28 high maternal blood glucose concentrations cause fetal hyperglycaemia, and this results in surplus fetal carbohydrate and stimulates fetal insulin production. Insulin, an anabolic hormone, enhances protein, lipid and carbohydrate synthesis. Thus, fetal hyperinsulinaemia in the presence of increased
Obstetric brachial palsy
Shoulder dystocia has been rightly called ‘the obstetrician's and midwife's nightmare’.33 The technical problem is to deliver a healthy baby and a healthy mother. The risks to the macrosomic infant concern the integrity of the upper limbs, characterised by obstetric brachial palsy, and avoidance of brain damage due to hypoxic ischaemia.
The incidence of Erb's palsy in the general population in the British Isles is 0.42 per 1000 live births and in the CEMACH study of pre-gestational diabetes
Cardiomyopathy
Cardiomyopathy was not identified in any of the babies in the CEMACH study but the condition has been long recognised as a complication of poorly controlled maternal diabetes.34
Autopsied cases of the very few infants of diabetic mothers who died have shown similar clinical, echocardiographic, and pathological findings to familial hypertrophic cardiomyopathy, except for less myocardial fibre disarray.35 The natural history of hypertrophic cardiomyopathy in infants of diabetic mothers is that
Hypocalcaemia and hypomagnesaemia
Metabolic disturbances in the form of hypocalcaemia and hypomagnesaemia have been reported to affect the babies of women with insulin-dependent diabetes mellitus.4, 5 Strict control of diabetes during pregnancy appears to reduce the risk for neonatal hypocalcaemia. Banerjee et al.41 suggested a possible mechanism: poor diabetic control leads to glycosuria and consequent increased urinary loss of magnesium and therefore a low maternal blood magnesium concentration. Maternal hypomagnesaemia leads
Hypoxic ischaemia
Maternal diabetes mellitus may predispose to fetal vulnerability to hypoxic ischaemia by increasing the likelihood of impaired placental blood flow. In 1949 White found evidence of arteriosclerosis in 33% of fetal losses, 33% of stillbirths and 42% of neonatal deaths.13 When arteriosclerosis in the young diabetic had progressed so far that the pelvic blood vessels were calcified, the fetal survival for the entire period of pregnancy was only 10%. He wrote:13
When the arteries of the pelvis are
Postnatal management
Between 2002 and 2007, CEMACH carried out the largest programme into pregnancy in women with type 1 and type 2 diabetes mellitus in England, Wales and Northern Ireland1; gestational diabetes was excluded. It included three modules: (1) a survey of diabetes maternity services for women with type 1 and type 2 diabetes (2) a descriptive study of 3808 pregnancies in women with diabetes, with follow-up to pregnancy outcome at 28 days after delivery14; (3) a confidential enquiry to investigate
The effect of pre-conceptional care
An important finding of the CEMACH study related to pre-conceptional care, which was poor: only 39% of women took folic acid before conception, only 35% were documented to have had pre-pregnancy counselling and only 37% of women with pre-existing diabetes mellitus had a blood glucose measurement before pregnancy.14 Thus, the majority of diabetic women in England, Wales and Northern Ireland in 2002–3 started on their pregnancy with suboptimal control of blood glucose: only 38% of these diabetic
Gestational diabetes mellitus
The CEMACH study looked at the outcomes for babies of women with pre-existing diabetes in the UK.1, 7, 14 By contrast, the Australian Carbohydrate Intolerance Study in Pregnant Women (ACHOIS) trial was designed to assess whether perinatal complications would be reduced by the active management of gestational diabetes, which affects up to 9% of pregnant women.54 Women with gestational diabetes who were between 24 and 34 weeks' gestation were randomly assigned to receive dietary advice, blood
Conclusions
There is no difference in complications for babies of women with type 1 and type 2 diabetes mellitus, and it is likely that the most important causative factor is a high maternal blood glucose concentration. This finding indicates that the condition is amenable to treatment insofar as it affects the baby, and studies have shown that improvement in outcome for the baby can be achieved through active management of the mother's diabetes. The most challenging aspect remains pre-conceptional blood
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