Managing gestational diabetes mellitus: Audit data of outcomes for women and neonates

Diagnosis of GDM

Approximately 5% of all pregnant women in England and Wales present with pre-existing or type 1 diabetes, of which 87.5% are women with GDM who have tendencies to develop long-term diabetes after pregnancy (NICE, 2015). Much debate has taken place about the benefits of screening for GDM but the evidence remains unclear as to the most effective diagnostic procedure and glycaemic thresholds (HAPO Study Cooperative Research Group, 2008; Benhalima et al, 2015; Farrar et al, 2017). Thresholds based on the hyperglycaemia and adverse pregnancy outcomes (HAPO) study (2008) and supported by the World Health Organization (WHO) (2013) are also recommended by NICE (2015), and in the previous NICE (2008) guidelines, universal rather than selective screening for GDM was recommended (Scott, 2002; Cosson et al, 2006; Tieu et al, 2010), with the aim of improving diagnosis, treatment and subsequent outcomes for both the mother and the neonate (Brown et al, 2016). Recently, however, Tieu et al (2017) showed that there was insufficient evidence to demonstrate that increased numbers of women with GDM diagnosed through universal screening improved fetal and maternal outcomes (Meek et al, 2015; Kennedy, 2017). In the updated NICE (2015) guidelines for diabetes care, the recommendations are for a risk assessment and testing for GDM if the following is identified:

In the past, there have been differing opinions as to what degree of glucose intolerance would diagnose a women with GDM (Lindsay et al, 2017). However, it is generally acknowledged that early diagnosis will reduce the risks to mother and baby and improve perinatal outcomes (Yogev et al, 2009). NICE (2015) recommend that blood glucose control is assessed through HbA1c levels and maintaining a level at 48 mmol/mol (6.5%) to ensure the impact of hyperglycaemia on the neonate is reduced. However, NICE (2015) does not recommend routine monitoring of HbA1c in women with GDM. HbA1c monitoring for women with pre-existing diabetes after the first trimester would not provide a level of risk for GDM. In addition, NICE (2015) does not recommend fasting plasma glucose for diagnosis of GDM and suggests that further selective testing via self-monitoring of blood glucose using a glucometer, followed by a 2-hour 75 g oral glucose tolerance test (OGTT) at 24-28 weeks' gestation if glycosuria is found to be at 2 or more as a single risk factor. GDM is diagnosed if the OGTT results indicates that plasma glucose is 7.8 mmol/L or above.

Managing GDM to improve outcomes

Women diagnosed with GDM are at increased risk of recurrence of this condition in subsequent pregnancies (Madazli et al, 2008; NICE, 2015). Older women and women from disadvantaged and migrant backgrounds have an increased risk of developing GDM (Carolan et al, 2012). In addition, obesity in pregnancy is associated with adverse pregnancy outcomes, such as increased hypertension and instrumental intervention during labour—although limiting gestational weight gain in obese women may improve obstetric outcomes (Simmons, 2011). A population-based study (Erjavec et al, 2016) to determine prevalence, predictors and perinatal outcomes of WHO diagnostic criteria for women with GDM suggested that induction of labour and caesarean section were predictive, although low Apgar scores in the neonate at birth were not indicated unless the women with GDM also had a BMI of above 30 kg/m².

An earlier systematic review and meta-analysis (Poolsup et al, 2014) examined the effect of treatment on GDM, comparing therapeutic intervention, such as diet or insulin, to routine antenatal care. The authors concluded that treating GDM significantly reduced macrosomia, shoulder dystocia and gestational hypertension; however, there were no differences in groups for perinatal and/or neonatal mortality, neonatal hypoglycaemia, birth trauma, pre-eclampsia, labour induction and caesarean section. Other studies have investigated the effects of a low glycaemic index diet on pregnancy outcomes in GDM and have concluded that there were no significant differences in women with GDM on this diet and those on a conventional high-fibre diet in terms of birth weight, prevalence of macrosomia, insulin treatment or adverse pregnancy outcomes (Louie et al, 2011). Similar findings were identified by Walsh et al (2012) although a low glycaemic index diet did have a positive effect on gestational weight gain and maternal glucose tolerance. These findings, in addition to lifestyle interventions such as physical activity, are supported by a further meta-analysis of randomised evidence to improve obstetric outcomes (Thangaratinam et al, 2012). A more recent study based in the US also suggest that improvements to diet and lifestyle before pregnancy is associated with a low risk of gestational diabetes and could prevent disease onset (Zhang et al, 2014).

However, a large multicentre randomised controlled trial (Poston et al, 2015) hypothesised that a combined intervention of a low glycaemic diet and physical exercise may have an effect on maternal weight gain in obese women during pregnancy, reducing the incidence of GDM and large for gestational age or macrosomic babies. Unfortunately, the results of this trial indicated that the combination of diet and exercise did not have any significant effects on outcomes for obese pregnant mothers and their babies when compared to obese women following routine antenatal care, and although diet and physical activity improved, there was no effect on the incidence of GDM or macrosomic babies in the intervention group. It therefore appears that other factors may have an impact on incidence of GDM and maternal and neonatal outcomes for obese women in pregnancy.

Timing of induction of labour for GDM

Updates about the timing of induction of labour for GDM have been issued by NICE (2015) to recommend that health professionals should discuss the timing and mode of birth with pregnant women with diabetes during antenatal appointments, especially during the third trimester. It is recommended that women with existing diabetes and no other complications are offered induction of labour or an elective caesarean section between 37+0 weeks and 38+6 weeks of pregnancy. An elective birth should be considered before 37+0 weeks' for women with type 1 or type 2 diabetes if there are any metabolic changes or other maternal/fetal complications. Women with GDM are advised to give birth no later than 40+6 weeks', and are offered elective birth (by induction of labour, or by caesarean section if indicated) if they have not given birth by this gestational age. In case of additional complications, elective birth should be offered before 40+6 weeks' for women with GDM (NICE, 2015).

The literature has been examined to explore the most effective approach to birth to reduce risks and adverse outcomes in women with GDM. Studies also sought evidence for the optimal gestational age for delivery of women with diabetes. Grabowska et al (2017) indicated that in births to women with GDM, 53% were by caesarean section and 70% of these were elective caesarean sections due to previous operative births. Overall, 12% were normal vaginal births and when comparing vaginal and caesarean section births, those that had an increased BMI and advanced maternal age resulted in a surgical birth. When induction of labour groups were compared to spontaneous start of labour groups, there were no differences in the number of vaginal births or an increase in intrapartum caesarean sections. The authors concluded that women with GDM were more likely to undergo caesarean section but that induction of labour did not increase this risk. However, other factors such as maternal age, increased BMI and insulin therapy were additional risk factors for surgical births. These findings supported previous research that suggests that induction of labour in women with mild GDM did not increase the caesarean section rate at <40 weeks' gestation. However, induction of labour at >41 weeks' gestation was associated with a threefold increase in caesarean section births although this finding was also found in women who were treated for expectant management of labour at 40 weeks' gestation (Sutton et al, 2014).

Further research confirms these findings in women with GDM who are induced before 40 weeks' gestation. This was also associated with lower rates of caesarean section compared with expectant management of labour, although there was an increased risk of neonatal intensive care admission when induction of labour was carried out at <39 weeks' gestation (Melamed et al, 2016). In a study by Stuart et al (2011), there was a significantly reduced risk of neonatal Apgar scores of <7 at 5 minutes after birth in women who had an elective caesarean section after 38 weeks' gestation, compared to those who had a vaginal birth, irrespective of whether the vaginal birth was spontaneous, natural or assisted. The authors suggested that timing of elective caesarean section may have a protective effect on the risk of low Apgar scores in a diabetic pregnancy. Decisions about the ideal timing for birth for women with diabetes in pregnancy should also consider other risk factors such as maternal age, parity, BMI, Bishop scores and maternal glycaemic control besides gestational age to ensure optimal maternal and neonatal outcomes (Bas-lando et al, 2014; Niu et al, 2014; Feghali et al, 2016).

Population

A total of 3908 women were admitted to the maternity unit in 2017, of whom 331 (8.47%) were diagnosed with GDM. The data for these women were examined to identify those from this population who had normal births, or who had spontaneous vaginal births but required intervention, such as induction or an instrumental birth. The GDM group was also compared to the total population for gestational age at time of induction, outcomes of induction of labour and caesarean section rates. The aim was to identify if GDM had an adverse effect on factors such as induction and outcomes for both mothers and neonates, and whether this was influenced by maternal BMI and neonatal birth weight.

Data collection

The initial data were collected by analysing maternity coding from women's notes and hospital-generated statistics. Data from maternity notes entered on a hospital database created codes for all women giving birth in this maternity hospital for 2017. Women with GDM were identified through specific coding and each feature or category had identified codes for parity, place of birth (Table 1), birth outcomes (Table 2), caesarean section outcomes (Table 3), GDM groups with and without induction of labour compared for maternal age, BMI and gestational age (Table 4), and maternal and neonatal outcomes compared for the two groups (Tables 5 to 7). Tables 1 to 7 present descriptive statistics and are self-explanatory.

The midwife's role in managing GDM

These results indicate that there is scope for midwives to play a key role in educating women about healthy lifestyles, especially diet and nutrition, in a bid to reduce obesity in pregnancy. Midwives have a unique opportunity to provide information and education about management and/or prevention of GDM (Carolan et al, 2012). Their role is to identify risk factors and selectively screen for GDM (Kennedy, 2017), but unfortunately, studies have shown that not all health professionals have the knowledge and training to correctly identify women at risk (Murphy, 2010). If the condition is recognised and carefully managed, then midwives have a valuable role in offering information, health promotion and support to help women to make the right decisions for their care and to normalise a medicalised experience of pregnancy (Rogers and Hughes, 2010).

The results from the audit identified a risk factor of increased obesity for women with GDM who were <29 years old. In addition, the findings suggested a greater number of women with GDM in the 30-39 group gave birth at >40 weeks' gestation, which could place these women at an increased risk. This also raises questions about the optimal timing for induction of labour (Niu et al, 2014; Feghali et al, 2016).

Persson et al (2011) explored the experiences of midwives providing care and counselling to women with GDM and concluded that health professionals experienced increased demands to enhance monitoring of these women. A fear of failure to identify women with GDM motivated midwives to use different strategies, such as intensifying diabetes screening and management of mother and fetus; therefore improving training in coaching and/or counselling sessions for midwives could improve the situation. In addition, midwives need to develop a strategy to work more closely with dieticians to reduce the risk of obesity in women with GDM, especially in women aged <29 years old. Up-to-date maternity notes, if completed correctly, can alert midwives to increasing BMI during pregnancy and instigate more rigorous blood glucose monitoring. Midwives could be supported to advise women to keep food diaries and activity logs (although such tools are subjective and women may not always be exacting in the details included). Other measurement tools include the Food Frequency Questionnaire (Barclay et al, 2008; Zhang et al, 2014) and the International Physical Activity Questionnaire (Craig et al, 2003) which may be more rigorous, although the ability of such measures to ameliorate maternal and fetal outcomes for obese childbearing women at risk of developing diabetes has been shown to be polarised (Zhang et al, 2014; Poston et al, 2015).

Women's experiences of GDM management

Education and support by midwives about diabetes in pregnancy; its management; and associated comorbidities, such as adverse risks to both mother and neonate, is key to empowering women to understand and make decisions about their care. There is some literature related to perceptions and experiences among women with GDM and their expectations in meeting their emotional needs (Nolan et al, 2011a; Parsons et al, 2014). A study by Figueroa Gray et al (2017) found that women with GDM requiring insulin treatment reported negative experiences, with the emotional impact lasting beyond pregnancy. Further research is required on other medications for GDM to provide alternative treatment options and informed choices; however, Hui et al (2014) identified that insulin treatment resulted in higher levels of anxiety and stress in women with GDM, compared with dietary control.

Carolan et al (2012) and Carolan (2013) suggested that women diagnosed with GDM experience a process of adjustment, which can be improved with midwifery support at each stage to self-manage the condition. An interest in achieving optimal health for their baby ensures women's receptiveness to interventions to improve glycaemic control and prevent the development of type 2 diabetes in the future. Recognising the needs of women with GDM may influence their behaviour towards the diagnosis. Receiving support to self-manage the condition, and meeting expectations may influence positive psychological responses to attempts to reduce the risks to the woman and neonate (Lawrence, 2011).

Limitations of the audit

This audit examined data from a cohort of women who delivered in one maternity unit in 2017. The focus was on women who developed GDM and the impact on maternal and fetal outcomes, in order to identify how maternity care for this group of women could be improved. A longitudinal study to follow up women and their neonates over a 5-year period would further clarify these outcomes and promote long-term strategies and interventions in terms of early diagnosis and management of GDM.