6








Characteristics of labour and delivery

 
     
 

KEY FINDINGS

  • There is a high induction of labour rate (39%) and a high caesarean section rate (67%) in women with type 1 and type 2 diabetes.
  • There is a high preterm delivery rate (36%), with the greatest single contributor to this rate being preterm caesarean section.
  • The spontaneous preterm delivery rate is twice that in the general maternity population.
 
 
 

6.1

 

Introduction

The core principle of the National Service Framework for Diabetes is the achievement of a good outcome and experience of pregnancy and childbirth for women with pre-gestational diabetes.1 With this principle in mind, this chapter provides a description of the events of labour and delivery for the 3474/3808 (91.2%) of women who had continuing pregnancies at 24 completed weeks of gestation and compares them with the experiences of the general maternity population. Judging how long to continue a pregnancy around term and how to deliver are key decisions for women with diabetes and health professionals. This chapter sets out to examine the indications for delivery and the timing of induction.

 
 

6.2

 

Onset of labour and mode of delivery

The events around childbirth for a woman with diabetes contrast significantly with those experienced by mothers in general. Table 6.1 shows that only a minority (18.0%) of women with diabetes went into spontaneous labour compared with 69% of mothers in general.2

 
 

6.2.1

 

Induction of labour

Women with pre-gestational diabetes were nearly twice as likely to be induced, 38.9% (Table 6.1) compared with 21% in the general maternity population.2 Induction for women with diabetes was more likely to result in emergency caesarean section, 43.0%, compared with 19% for mothers in general.3

Routine induction because of maternal diabetes was the commonest indication for induction of labour, accounting for 654/1350 (48.4%) of all inductions and 36/253 (14.2%) of inductions before 37 completed weeks of gestation. The largest proportion of ‘routine’ inductions occurred between 38+ 0 and 38+ 6 completed weeks of pregnancy (Table 6.2).

 
 

6.2.2

 

Mode of delivery

The caesarean section rate was three times that for mothers in general, 67% compared with 22% (Table 6.3). Spontaneous vaginal delivery accounted for 24% of deliveries in women with diabetes compared with 67% in the general maternity population.

 
 

6.2.3

 

Caesarean section

The indications for elective and emergency caesarean sections are shown in Table 6.4. Where more than one indication was given, a principal indication was assigned after consideration of free text (see section 1.2.3). The indications for caesarean section performed at less than 37 completed weeks of gestation are shown in Table 6.5.

The two main contributing reasons for caesarean section overall were presumed fetal compromise (28.3% compared with 22% in the general maternity population) and previous caesarean section (24.9% compared with 14% in the general maternity population).3 However, caesarean section for failure to progress (13.9%) contributed less to the overall caesarean section rate than the rate for the general maternity population (21%).3

Four percent of all caesarean sections and 2.4% of preterm sections were performed without any specific obstetric or medical indication (either ‘routine for diabetes’ or ‘maternal request’).

 
 

6.3

 

Preterm delivery

A total of 1243 (35.8%) of all women with diabetes had a preterm delivery before 37 completed weeks of gestation (Table 6.2). This compares with a rate of 7.4% for the general maternity population.2

The spontaneous preterm delivery rate (including preterm premature rupture of the membranes requiring induction) was 325/3474 (9.4%), nearly twice that of 4.7% in the general maternity population.2

Three-quarters of all preterm deliveries were iatrogenic and the majority of these were preterm caesarean sections (Table 6.6). Some 206/940 (21.9%) of these preterm caesarean sections were for previous caesarean section, large baby, maternal request or routine for maternal diabetes.

 
 

6.4

 

Discussion

It is currently accepted practice that all women with pre-gestational diabetes should be delivered by 40 weeks of gestation to minimise the risk of stillbirth.1 Within this context, it is recommended that every effort should be made to avoid neonatal and maternal morbidity if at all possible, by careful consideration of timing and mode of delivery on a case-by-case basis.

The induction of labour rate was 39%, twice that in the general maternity population. Half of all inductions and 14% of preterm inductions were carried out as a routine policy due to maternal diabetes. There is a potentially higher risk of neonatal respiratory morbidity at earlier gestations, especially in women with suboptimal glycaemic control,4 and this should be taken into account when planning the timing of routine induction of labour for maternal diabetes.

The total caesarean section rate in the cohort was 67%, three times higher than the national average.3 The main contributors to this rate were emergency caesarean for presumed fetal compromise and repeat caesarean for previous caesarean section, both of which represented a higher percentage of the overall caesarean section rate than in the general maternity population. There is likely to be a constellation of factors behind these findings, such as the need to establish labour before 40 weeks of gestation, maternal pre-eclampsia and health professionals' concerns about fetal wellbeing, shoulder dystocia and uterine rupture. It is recognised that clinicians have a difficult task in evaluating the relative risks and benefits of alternative management approaches. The woman and her partner should be fully involved in the decision-making process.

The women in this study had a high (38%) emergency caesarean section rate. While the ratio of emergency to elective caesarean section in this study is the same as in the general maternity population, it is of concern that more than one-third of women, who are by definition, high risk, undergo emergency surgical intervention. It is suggested that future research should be undertaken in this area to explore the possible underlying factors.

Four percent of all caesareans were performed without a specific medical or obstetric indication. This is likely to impact on these women's obstetric future, as caesarean section rates are trebled in women with a previous caesarean section and this is likely to be further compounded by diabetes.3 Vaginal delivery is the ideal mode of delivery for women with diabetes. Every effort should be made to minimise the potential for future morbidity by avoiding caesareans that are not clinically indicated.

There was a nearly five-fold increase in the preterm delivery rate compared with the general maternity population. This was mainly because of preterm caesarean sections performed before 37 completed weeks of gestation. While 37% of these procedures were performed for presumed fetal compromise, over one-fifth were carried out for elective indications (routine for diabetes, large baby, previous caesarean and maternal request). It is important to ensure that women with diabetes are not delivered prematurely unless there is an appropriate indication, in order to decrease the burden of neonatal morbidity, additional neonatal care and the emotional impact of separation.

 
 

6.5

 

Conclusions

Women with diabetes have a high rate of obstetric intervention, both before and during labour. This is likely to be due, in part, to the conflict faced by health professionals between achieving a normal vaginal delivery and concerns about adverse pregnancy outcome.

 
     

References

  1. Department of Health. National Service Framework for Diabetes (England) Standards. London: The Stationery Office; 2001 [www.doh.gov.uk/nsf/diabetes/index.htm].
  2. Department of Health. NHS Maternity Statistics, England 2002–03. Statistical Bulletin 2004/10 [www.dh.gov.uk/PublicationsAndStatistics/Statistics/StatisticalWorkAreas/StatisticalHealthCare/StatisticalHealthCareArticle/fs/en?CONTENT_ID=4086521&chk=wV7ZSA].
  3. Royal College of Obstetricians and Gynaecologists, Clinical Effectiveness Support Unit. The National Sentinel Caesarean Section Audit Report. London: RCOG Press; 2001.
  4. Landon MB, Gabbe SG, Piana R, Mennuti MT, Main EK.Neonatal morbidity in pregnancy complicated by diabetes mellitus: predictive value of maternal glycemic profiles. Am J Obstet Gynecol 1987;156:1089–95.
  5. Confidential Enquiry into Maternal and Child Health. Maternity Services in 2002 for Women with Type 1 and Type 2 Diabetes. London: RCOG Press; 2004.