Interventions during childbirth in New Zealand

When the term 'women giving birth' is used, the numbers presented are births and are the number of women giving birth during the calendar year (ie, from 1 January to 31 December). A woman who had twins or a multiple birth is counted as having had one birth. A woman who gave birth twice within the same calendar year is counted twice.
The number of births presented includes only live births recorded in the Maternity Collection (MAT) at any gestation, and where a birth has a registration or birth record reported in the National Minimum Dataset (NMDS). Where a birth has an equivalent death registration recorded in the New Zealand Mortality Collection, the birth is also excluded from the analysis.
Deprivation is derived according to the residence of the individual. Numbers and rates are presented by deprivation quintile, ranging from quintile 1 (least deprived) to quintile 5 (most deprived). Deprivation scores are based on the 2006 New Zealand Deprivation Index for women giving birth before 2010, on the 2013 Deprivation Index for women giving birth from 2010 to 2015 and on the 2018 Deprivation Index from 2016 onwards.

Induction: the process of artificially stimulating the uterus to start labour by artificial rupture of membranes or pharmacological means.
Augmentation: the process of stimulating the uterus to increase the frequency, duration and intensity of contractions after the onset of spontaneous labour by artificial rupture of membranes or pharmacological means.
Epidural: a regional analgesic agent being injected into the epidural space of the spinal cord.
Episiotomy: an incision of the perineal tissue surrounding the vagina at the time of birth to facilitate delivery

Each individual represented in the data is allocated to a single ethnic group, using the following priority system: Māori > Pacific peoples > Indian > Asian (excl. Indian) > Other > European. Individuals of European and of Other ethnicities are often grouped together and presented as being part of the 'European or Other' ethnic group due to small numbers in the ''Other' ethnic group.
People giving birth may have more than one of these procedures.

The dataset describes people having an obstetric intervention (induction, augmentation, epidural or episiotomy) during labour and birth. This does not include all possible interventions.
People who had their labour both induced and augmented are recorded as having had an induction only. Therefore, the number of augmentations presented may be lower than the true number.
The number and percentage of inductions, augmentations and epidurals presented do not include people giving birth by elective caesarean section. The number and percentage of episiotomies is limited to vaginal births (all births excluding caesarean sections). It should be noted that people giving birth may have had more than one of these interventions.

While the data is collected for 'women' it is important to note that it actually includes all people who have given birth and that the data may include some transgender people.

From 1 July 2019, diagnoses codes are assigned using the 11th Edition of ICD-10-AM (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification) and procedure codes are assigned using the 11th Edition of ACHI (Australian Classification of Health Interventions) (Source: The Independent Health and Aged Care Pricing Authority).
Some maternity events (women giving birth in hospital and live babies born in hospital) are impacted by changes in the 11th Edition clinical coding standards, particularly place of birth and type of birth data. Therefore, this data may show variation due to the change in coding standards rather than a true increase.
The Primary Maternity Services Notice 2021 came into force on 29th November 2021, introducing changes to the terms and conditions on which maternity providers can claim for providing primary maternity services. This revokes the Primary Maternity Services Notice which came into effect on 1 July 2007 and its amendments.
There are underlying changes to the way some data are now captured (such as smoking status or breastfeeding and Well child referral). Also some metrics are no longer collected (such as height and weight at registration, which impacts on BMI calculation). It is important to consider these changes when comparing claims data pre and post November 2021.

At URL provided, under 'Labour and birth ' heading, select 'Download full datasets' and 'WGB_interventions_table' file.

The National Maternity Collection collates data from three different sources to provide statistical, demographic and clinical information about women giving birth and live-born babies in New Zealand.
Data for the web tool was extracted from publicly funded maternity events recorded in Te Whatu Ora - Health New Zealand's National Maternity Collection on 12 May 2023.

To provide annual health statistics about women giving birth, their pregnancy and childbirth experience and the characteristics of live-born babies in New Zealand.

Population data for rate calculations was provided by Stats NZ