Report on Maternity, 2010

Summary

Report on Maternity, 2010 summarises the maternal and newborn information stored in the National Maternity Collection. This collection uses two administrative sources of data: hospital discharge data from the National Minimum Dataset (NMDS) and information on primary community events from lead maternity carer (LMC) claim forms.

Key facts

In the 2010 calendar year the National Maternity Collection reported that:

• 64,433 women completed 64,485 pregnancies
• 64,936 babies were born live.

Maternal demographic profile

In the 2010 calendar year:

• approximately one in four women giving birth were Māori (25.4%)
• about a quarter of women giving birth were either Pacific (11.7%) or Asian (10.8%)
• over half (52.2%) of all women giving birth were grouped into the Other ethnic group (the majority of these, 96.1%, were European)
• the most common age group for a woman giving birth was 30–34 years (27.6%)
• the median age of women giving birth was 29 years
• Māori women generally gave birth at a younger age than women of other ethnicities (median age 25 years)
• the national birth rate was 7.0 completed pregnancies per 100 women of reproductive age (15–44 years)
• Asian women had the lowest birth rate (5.3 completed pregnancies per 100 women of reproductive age)
• Pacific women had the highest birth rate (11.4 completed pregnancies per 100 women of reproductive age)
• over a quarter (27.8%) of all women giving birth lived in the most socioeconomically deprived areas (quintile 5)
• the majority of Pacific women giving birth (57.5%) lived in the most socioeconomically deprived areas (quintile 5)
• younger women giving birth were more likely to live in a socioeconomically deprived area.

Labour and birth

In the 2010 calendar year:

• the majority (65.0%) of women gave birth by spontaneous vaginal delivery (including home births), down from 2004 (66.1%)
• almost a quarter of women (23.6%) gave birth by caesarean section, up from 2001 (21.3%)
• the percentage of spontaneous vaginal births decreased with the maternal age (74.0% of women under 20 years of age compared with 51.9% of women aged 40 and over), while the opposite trend was seen with caesarean section births (14.2% of under-20-year-olds compared with 38.5% of women aged 40 and over)
• Māori and Pacific women were more likely to have a spontaneous vaginal birth (74.9 and 71.5%, respectively) than women in the Asian and Other ethnic groups (57.4% and 60.4%, respectively)
• the percentage of women giving birth by caesarean section decreased with level of socioeconomic deprivation, ranging from 28.9% for the least deprived women to 19.4% for the most deprived women; the opposite trend was seen with spontaneous vaginal births
• of the 15,250 women who had a caesarean section in 2010, just over a half had an emergency caesarean section (54.9%)
• one in five women  (19.8%) were induced,  and an epidural  was administered to almost one in four women  (24.9%)
• the national rate for episiotomies  was 12.5 per 100 women giving birth vaginally
• almost a third (28.6%) of all women giving birth  required augmentation of labour
• the induction rate increased with maternal age: 16.0% of women aged under 20 years were induced, compared to 34.5% of women aged 40 years or over
• Asian women had the highest (33.9%) epidural rate and Māori women had the lowest (15.9%)
• 1.5% of women gave birth to either twin or multiple babies (944 women)
• the national home birth rate was 3.2%
• women aged 30–34 years had the highest rate of home births (3.7%)
• Pacific and Asian women had the lowest rate of home births (1.0%)
• women residing in the most deprived areas (quintile 5) had the lowest rate of home births (2.6%).

Babies

In the 2010 calendar year:

• slightly more male (51.4%) than female babies were born
• over a quarter (26.5%) of all babies were of Māori ethnicity
• the average birthweight was 3.42 kilograms, with female babies weighing less on average (3.37 kg) than male babies (3.47 kg)
• 7.4% of all liveborn babies were born pre-term (under 37 weeks’ gestation)
• the rate of pre-term births increased with socioeconomic deprivation, ranging from 7.0% (least deprived) to 7.8% and 7.5% (quintile 4 and 5 respectively)
• Māori babies were the most likely to be born pre-term (8.1%)
• 1.8% of full-term  babies were born with a low birthweight (< 2.5 kg)
• full-term liveborn babies were most likely to have a low birthweight (< 2.5 kg) if they were of Asian ethnicity, lived in the most deprived areas, or were born to women aged 40 years and over (2.9%, 2.2% and 2.9%, respectively).

Lead maternity carer (LMC)

In the 2010 calendar year:

• 55,254 (85.7%) women were registered with an LMC at some point during the pregnancy or postnatal period
• the remaining 14.3% of women either received care through district health board (DHB) services or received no primary maternity care
• Pacific women were the least likely group to be registered with an LMC (34.1% were not registered)
• the rate of LMC registration decreased with socioeconomic deprivation: the registration rate ranged from 91.9% for the least deprived women to 77.1% for the most deprived women
• the majority of women were registered with a midwife LMC (91.6% of those women who were registered with an LMC)
• 16.2% of all women registered with an LMC smoked (as reported at the time of LMC registration)
• over a third (38.4%) of all Māori women smoked at the time of LMC registration
• the rate of smoking increased with the level of maternal socioeconomic deprivation, ranging from 5.6% of women residing in the least deprived areas to 26.6% of women residing in the most deprived areas
• the breastfeeding status (at two weeks of age) was known for over three-quarters of all babies (75.9%)
• the majority (91.9%) of these babies were breastfed either exclusively  (70.4%), fully (9.4%) or partially (12.1%)
• Māori babies were the least likely to be breastfed (and the most likely to be artificially fed), with 11.7% receiving some alternative to breast milk.

Maternity facilities

Maternity facilities are classified as primary, secondary or tertiary  according to the availability of specialist services, with tertiary facilities providing the most specialist services. (See Appendix C: Catchment areas for a list of available maternity facilities by region.)

In the 2010 calendar year:

• the majority of women gave birth at either a tertiary (44.7%) or a secondary (40.7%) facility
• just over a 10th of women gave birth at a primary facility (10.8%)
• the use of tertiary facilities increased with the maternal age: over half (53.5%) of women aged 40 and over gave birth at a tertiary facility, compared to 36.5% of women aged under 20 years
• the majority of Pacific and Asian women gave birth at a tertiary facility (67.5% and 61.7% respectively)
• women living in the most deprived areas were the most likely to give birth at a primary facility (13.2% of quintile 5 women).