< Previous | Contents | Next >

1999 Health in Scotland

PREGNANCY AND DELIVERY

The most reliable estimate of the number of babies born in Scotland each year is derived from the civil registration system administered by the Registrar General for Scotland, which is based on the date of registration rather than of birth. These data identify a consistent decline in the crude birth rate from 13.0 births per 1000 population in 1975 to 10.8 per 1000 in 1999. The proportion of hospital deliveries has remained constant at approximately 99% over this period. The mean maternal age at first birth has risen gradually from 24.4 years in 1989 to 26.0 years in 1996 and to 26.2 years in 1999, a rise attributable to the number of babies born to women aged 35 years or more. The maternity inpatient and day case record (SMR02) has achieved a national coverage of over 98% of all births and Table 2.5 shows the mode of delivery. In 1999, 41% of live births were to unmarried parents but over 60% of these were jointly registered by parents living at the same address.

Table 2.5 Mode of delivery of all live births^1,2 and percentage of singleton and multiple live births that were induced in Scotland, 1990 to 1999

Preterm and low birthwieght babies

The problems posed by preterm birth and low birthweight babies remain core issues in both perinatal healthcare and subsequent child health and well-being. The overall rates of preterm births (less than 37 weeks gestation) have remained stable at approximately 7.1% of all live births for the last 4 years, while the rates of very- and extremely-preterm babies have also remained constant. The same trend is evident overall for the low birthweight babies (less than 2,500 grammes) that account for approximately 7.0% of all live births (Table 2.6). In singleton pregnancies the rate of preterm births has remained constant at 5.9% in 1999, while the rate of low birth weight babies rose slightly from 5.6% in 1998 to 5.8% in 1999. The association continues between preterm birth and low birthweight and socio-economic status, maternal age (a U-shaped relationship), smoking, previous birth of a low birthweight or preterm baby, multiple births and a short birth interval.

Table 2.6 Proportion of preterm and low birthweight babies born in Scotland, 1990-1999, expressed as a percentage of live births.

Caesarean section

The proportion of babies born by emergency, elective and total caesarean sections continues to increase, the total caesarean section rate having risen from 14.6% in 1990 to 19.7% in 1999. The same trend is evident in most westernised countries. There has been a reciprocal decline in the rate of forceps, vacuum extraction and breech deliveries, while the steady increase in induction of labour is maintained; 27.1% of pregnancies were induced in 1999 compared with 21.1% in 1990. The rise in caesarean section rate (from 5% in 1970 to 19.7% in 1999) has not been uniform across maternity units in Scotland, even when adjustment is made to control for population differences. The range of variation between maternity units in caesarean section rates in the following selected groups of women in the period 1992 and 1997 in Scotland is shown in parentheses:

• Primigravida at term, spontaneous labour, singleton cephalic infant (6.2-12.6%)
• Primigravida at term, mother younger than 35 and taller than 155 cm (4.8-11.2%)
• Multiparae, previous caesarean section, at term, singleton cephalic infant (37-73.9%)
• Elective caesarean section rate, all mothers as above, one previous caesarean section (10.6- 55.8%)
• Primigravida at term, singleton breech infant (84.2 - 98.8%)
• Multiparae, no previous caesarean section, singleton breech infant (59.7 -98.7%)

The Scottish Executive of the Royal College of Obstetricians and Gynaecologists in partnership with ISD has used 10 standard sub-groups to study caesarean section rates. During 1992 to 1997, 48,602 caesarean sections were performed (in 300,733 deliveries) and the relative contributions of the various groups are as follows :

Women in sub-groups 1, 5, 6 and 7 accounted for 60% of all caesarean sections. Group 1 (primigravida at term and spontaneous labour) accounted for 17.3% of all caesarean sections; this is a key statistic if the incidence of caesarean sections is to be reduced. Women in Group 5 (previous caesarean section and at term in current pregnancy) accounted for 23.7% of all caesarean sections and the total repeat caesarean section rate was 53.8% (range 37% to 73.9%), while the elective repeat caesarean section rate for all women with one previous caesarean section was 30.3% (range 10.6% to 55.8%). The vaginal delivery rate in women who had one previous caesarean section varied from 62.5% to 30.1%.

There appears to be a five-fold difference in repeat elective caesarean section rates in various maternity units, a variation that cannot be explained by differences in obstetric populations. The extent to which the maternal request for caesarean section is contributing to the rising rate is not known.

Groups 6 and 7 (singleton breech presentation) accounted for 18.9% of all caesarean sections, 10.5% in primigravida and 8.4% in multiparae. The national caesarean section rate in units undertaking at least 1000 deliveries per annum for all singleton breech presentations in primigravida was 88.9% (range 81.3% to 95.6%) and in multiparous women it was 80% (range 65.3% to 97%). The national caesarean section rate for all singleton breech presentations in primigravida at term was 93.6% varying from 84.2% to 98.9%, while the national rate in multigravide was 83.8% varying from 68.8% to 99% by unit. To determine whether the variation in rate among units was related to a history of previous caesarean section, the records of only multiparous women with a breech presentation at term and no previous caesarean section were reviewed. This showed a national caesarean section rate of 78.5% with a variation between units of 59.7% to 98.7%.

This caesarean section review over a 5-year period has identified a marked variation in the caesarean section rate between maternity units, a variation that cannot be explained by case mix. The following action is recommended:

• All units should review their caesarean section practice regularly;
• National guidelines should be established for the management of primigravida in labour at term (including the role of fetal blood sampling and use of syntocinon) and the use of external cephalic version in breech presentation;
• An audit of the management of breech presentation should be undertaken;
• A study of the views of women and professional staff should be undertaken in relation to the elective use of caesarean section in women with one previous caesarean section.

Reproductive loss

There were 286 stillbirths in 1999, the lowest total ever recorded. The Scottish Stillbirth and Infant Death Report for 1998 was produced as part of the work of the Scottish Programme for Clinical Effectiveness in Reproductive Health. It provided detailed analysis of stillbirth and infant death rates. Information on stillbirths, infant deaths and live births registered in 1998 was provided by the General Register Office: the SMR02 returns provided data on the 1998 discharges from maternity units: and the report collated additional information on stillbirths, neonatal deaths and post-neonatal deaths (Table 2.7). Data for 1999 were not available when the Report was compiled but have been added to Table 2.7 to show continuing trends.

Table 2.7 Stillbirths and deaths in the first year of life in Scotland, 1994-1998

Figure 2.15 Stillbirth, neonatal and postneonatal mortalityrates in Scotland, 1974-1998

Within all categories of death there was a slight fall in 1999 rates in comparison to 1998, but in general rates were similar to those of previous years, although showing a downward trend. Use of the FIGO system (which permits an estimation of notional preventable mortality among normally formed fetuses weighing 1000 grammes or more) showed that the notional preventable stillbirth rate rose only slightly from 3.2 per 1000 total births in 1997 to 3.7 per 1000 in 1998. This increase was attributable to an increase in the number of antepartum stillbirths with 86% occurring at less than 40 weeks gestation, the intrapartum stillbirth rate having decreased since 1997. The overall neonatal death rate rose insignificantly between 1997 and 1998 while the notational preventable neonatal mortality rate rose slightly from 0.9 to 1.0 per 1000 live births. This increase is almost entirely attributable to deaths associated with prematurity mainly consisting of lung immaturity and hyaline membrane disease.

The 1998 rate of 5.5 stillbirths per 1000 total singleton births was insignificantly greater than the rate of 5.0 per 1000 in 1997 but lower than the rate of 6.0 per 1000 between the years 1993 to 1996. The neonatal death rate of 2.8 per 1000 total singleton live births in 1998 was identical to the 1997 rate and significantly lower than the rates in the period 1993 to 1996. A similar pattern to previous years was observed in the causes of stillbirth: 58% were unexplained, and the common identifiable causes were antepartum haemorrhage (12%), hypertension (12%) and congenital anomaly (11%). In neonatal singleton deaths, 39% were unexplained and 29% were associated with a congenital anomaly.

The perinatal mortality rate was slightly higher in 1998 than in 1997 but lower than in previous years.

The 1996 twinning rate of 14.3 per 1000 maternities was insignificantly higher than in previous years (1997 rate 13.4) and the risk of deaths from any cause remained higher in multiple births compared to singletons. Both the stillbirth rate of 24.9 per 1000 multiple total births and the neonatal death rate of 29.2 per 1000 multiple live births rose significantly in comparison with 1997 (17.5 and 16.6 per 1000 respectively), but rates were similar to those of previous years. The effects of prematurity account for a disproportionate number of deaths among multiple births: 80% of multiple neonatal deaths were in the 'unexplained - 2500 grammes' category compared to 30% of singleton deaths. Lung immaturity and hyaline membrane disease account for 76% of neonatal deaths in multiple births compared with 38% of singleton neonatal deaths.

In general, males of any age have a higher mortality rate than females. The 1998 stillbirth rate was 5.9 and 5.0 for 1000 births for males and females respectively and the neonatal death rates were 3.1 and 2.5 for 1000 live births for males and females respectively. While preterm and premature births (either due to a birth weight of less than 2500 grammes of a gestation of less than 37 weeks) accounted for under 6% of singleton total births, they accounted for 60% of stillbirths and neonatal deaths. Any observed variation in stillbirths, neonatal and post-neonatal death rates between Health Boards is no greater than might be expected through chance.

The extended perinatal mortality rate is an estimate of the reproductive loss from 20 weeks gestation to the end of the first year of life. This rate was 14.7 per 1000 total births plus late fetal deaths in 1998, marginally higher than the 1997 rate of 13.8 per 1000 and lower than the 1995 and 1996 rates of 16.1 and 15.5 per 1000 respectively.

Sudden infant death syndrome (cot death)

Sudden and Unexpected Death in Infancy became a registrable cause of death in 1971, which meant that many unexplained deaths, which would have been attributed to respiratory causes, were increasingly registered accordingly. In 1979 the coding system was again revised and the term Sudden Infant Death Syndrome (SIDS: ICD9 79.0) was introduced. During the late 1970s and early 1980s, the number of such deaths in Scotland was approximately 150 per annum, a rate of 2 to 2.5 per 1000 live births.

While the change in registration may account for an apparent increase in the incidence of SIDS, it should be remembered that in the early 1970s babies were placed in the prone sleeping position as this was thought to improve respiratory function and reduce vomiting from gastro-oesophago reflux. In the late 1980s interventional studies pointed to a relationship between prone sleeping and sudden infant death and in 1991 the UK Government introduced the "Reduce the Risks" campaign. In 1990 there were 131 SIDS deaths in Scotland but the figure fell rapidly to 62 in 1992 declining further to 41 in 1999. The decrease in Scotland is reflected in other Westernised countries who have offered the same advice during the same period

Despite the reduction, SIDS still accounts for the largest group of infant deaths (after those attributable to perinatal causes and congenital anomalies), and is the most common cause of death amongst babies aged one week to one year. SIDS is probably multifactorial with interaction between physiological, maternal, infant and environmental factors. It is uncommon in the first month of life and it is most common between the second and fourth month, and the rate declining sharply after 6 months. Eighty-five per cent of sudden infant deaths occur in babies under 6 months, while approximately 3% are in the second year of life. Risk factors confirmed by the 1992-1995 Scottish SIDS Case Control Study are as follows:

• Male/female ratio of greater than 2:1;
• Seasonal peak between November and February;
• Second or later babies are at more risk than first born;
• Maternal smoking during pregnancy (This increases the odds ratio (OR) univariate analysis to 5.26, paternal smoking increases it to 1.72, and having both parents smoking increases it to 7.92. It is difficult to separate the antenatal from postnatal smoking risk given that smoking is seldom confined to one period);
• Increasing deprivation category (even after correcting for smoking);
• Young mothers;
• Twins;
• Prematurity and low birthweight babies (Babies in these categories accounted for 25% of the deaths in the Scottish study compared with 8% of the general population);
• Placing babies in the prone sleeping position (This was associated with an odds ratio of 5.37, compared with a side sleeping OR of 1.58 and a supine sleeping reference OR of 1.0).

A recent Confidential Enquiry case control study in England entitled "Sudden Infant Deaths in Infancy" identified that in 80% of cases, no cause of death was found despite extensive investigation. The majority of the findings were consistent with those of the earlier Scottish study: a shift of SIDS towards extreme poverty and socio-economic deprivation; a reduced seasonal peak with an excess of male deaths in warmer months; those infants requiring resuscitation or admission to SCBU were at higher risk (although the known social and economic antecedents are common for SIDS, low birthweight and prematurity). A reduction of risk was associated with prior immunisation, placing the cot in the parental bedroom for a period of 6 months and breastfeeding (although no dose-response effect was discerned). No associated risk or benefit was attributed to cot bumpers, dummies, flying or high altitude, apnoea monitors and mattress type or covering. No support was adduced for the toxic gas - fungal infection hypothesis.

Sudden infant death syndrome remains a major challenge. As the causation and associated risk factors become clearer, the training of health professionals who care for babies and families, should reflect increasing awareness of risk and benefits in regard to SIDS and become incorporated into normal clinical care, while health education and promotion must be targeted to those groups at greatest risk. A programme of continuous development between the Scottish Cot Death Trust, health professionals and the Scottish Executive is currently underway, including a review of the investigation and management following a sudden infant death.

< Previous | Contents | Next >