What we know so far - key findings from our reports

Growing Up in New Zealand produced six major reports so far. Some provide an overview of the cohort at a particular age, some investigate topics such as vulnerability or residential mobility. All year round, the team publishes scientific and working papers, and releases topical policy briefs for policy developers and government agencies.

Key findings from the 'Vulnerability and Resilience' series (two reports released in 2014 and 2015)

'Exploring the definition of vulnerability' and 'Transitions in exposure to vulnerability' are the first two in a series of reports exploring aspects of vulnerability and resilience within the context of our unique population and the New Zealand environment.


Findings from the 'Exploring the definition of vulnerability' report (2014)

  • Risk factors used to define vulnerability tend to cluster in the New Zealand context, notably according to: maternal characteristics and behaviours; features of the proximal home environment; and pregnancy specific conditions including poor maternal mental wellbeing and poor physical health in late pregnancy.
  • Clustering of risk factors that define vulnerability is common, but risk factors do not cluster uniformly across the population; it differs across population subgroups in New Zealand, with marked variation in exposure according to maternal ethnicity.
  • Relative exposure to vulnerability can be estimated by summing the total number of risk factors that children are exposed to at any one time point or over time.
  • Māori and Pacific children tend to be exposed to a greater number of risk factors for vulnerability than New Zealand European or Asian children at each time point and across multiple time points.
  • Exposure to multiple risk factors for vulnerability at any one time point increases the likelihood that children will experience poor health outcomes during their first 1000 days of development.
  • Cumulative exposure to multiple risk factors throughout infancy increases the likelihood of experiencing common childhood infections such as ear infections as well as more serious respiratory illnesses requiring hospitalisation.
  • Not all children who are exposed to risk factors for vulnerability experience specific poor health outcomes, although they are at in creased risk than those experiencing few or no risks.
  • Children who are exposed to no or few risk factors for vulnerability may also experience poor health outcomes during their early years.
  • Identification of solutions to reduce the effects of early exposure to risk factors for vulnerability is likely to require cross-agency interventions as risk factors tend to cluster and exist across multiple domains.
  • At an individual level exposure to risk factors for vulnerability during early life is not necessarily constant, and exposure profiles may change significantly over time.

Read the full results in our Exploring the definition of vulnerability report


Findings from the 'Transitions in exposure to vulnerability' report (2015)

Vulnerability in early life (from before birth to age two)

  • Living in an area of high deprivation, having a mother who was experiencing financial stress or on an income tested benefit, or experiencing overcrowding were the most common vulnerability risk factors for children in early life.
  • Over half of all cohort children were exposed to at least one, and approximately 1 in 10 to four or more risk factors either before their birth, or at nine months or at two years of age.
  • Some risk factors tend to occur on their own, or with just one other risk factor. Experiencing financial stress, maternal depression and poor maternal physical wellbeing commonly occurred alone.
  • Those risk factors that were more likely to occur together were maternal age (teen parent), maternal smoking, being on an income tested benefit, living in a public rental home, having no partner and having no secondary school education.

Changes in exposure to vulnerability in early life (from before birth to nine months)

  • Approximately 28% of children experienced changed vulnerability risk groups between the antenatal period and nine months of age.
  • Maternal smoking and living in public rental accommodation (or social housing) were the risk factors least likely to have changed between the antenatal period and nine months of age.
  • Experiencing financial stress, poor maternal health (mental and physical) and being unemployed were the risk factors most likely to have changed between pregnancy and nine months of age.

Influence of maternal, family and neighbourhood characteristics on high vulnerability risk in early life

  • Transitions in vulnerability risk were associated with maternal, family, and neighbourhood characteristics.
    • Having more perceived stress, a current disability, an unplanned pregnancy, and being born outside New Zealand were maternal characteristics associated with persistently high vulnerability, or with increased vulnerability exposure
    • Having less family support, more family stress and more relationship stress were family characteristics associated with persistently high vulnerability, or with increased vulnerability exposure
    • Feeling less integrated into the neighbourhood, and having less support (outside of family support) were neighbourhood characteristics associated with persistently high vulnerability, or with increased vulnerability exposure.

Effect of high vulnerability on children’s health and behaviour by age two

  • Those children who were exposed to persistently high vulnerability risk were more likely to have experienced chest infections, and to have incomplete immunisations by the age of two years
  • Ear infections did not seem to be related to differential exposure to risk factors
  • There was a small, but not significant, protective effect on other two-year health outcomes when moving out of stably high vulnerability risk
  • Those children exposed to high vulnerability risk during the antenatal period, or at nine months, were more likely to fall into the ‘abnormal’ SDQ category
  • Those children who experienced persistently high vulnerability risk, and those who experienced an increase in vulnerability risk were more likely to fall into the ‘abnormal’ SDQ category when compared to those who were in the stably low vulnerability risk group

Social service access

  • The majority of families who had accessed Child Youth and Family or Family Start by age two years had been in the high vulnerability risk group during late pregnancy, however there was a small proportion of families using these services who had no vulnerability risk factors during late pregnancy
  • The largest proportion of families accessing Whānau Ora, or Parents as First Teachers, were in the medium vulnerability risk group during late pregnancy. Less than 10% of those families using Parents as First Teachers were from the high vulnerability risk group.

Read the full results in our Transitions in exposure to vulnerability in the first 1000 days of life report


Key findings from Residential Mobility Report 1: Moving house in the first 1000 days (2014)


The New Zealand context of residential mobility is diverse and complex. The analysis of Growing Up in New Zealand data has provided the following key conclusions:

  • Moving house is a frequent event in the lives of New Zealand families. In fact, the level of residential mobility described in the Growing Up in New Zealand cohort is greater than that demonstrated in other comparable cohorts (such as that of the Millennium Cohort in the UK).
  • Residential mobility during the first two years is associated with aspects of parental demographics, employment, housing tenure and structure, and neighbourhood level characteristics for New Zealand children.
  • The key determinant of mobility between birth and the age of nine months, and between nine months and two years of age for the Growing Up in New Zealand cohort is the housing tenure that families are living in. Families living in private rental accommodation are the most likely to move in this early period of life. Variation in the proportion of families in different housing tenure types in New Zealand compared to other countries may in part explain the differing rates of residential mobility seen. Improving the security of housing tenure in New Zealand, particularly in the private rental market, may protect families from undesired moves.
  • In the first 1000 days of life in New Zealand, residential mobility is also higher for those cohort children who are a first child, and those children who are living in less traditional household structure types (with their parent(s) as well as additional adults such as extended family members or non-kin).
  • The longitudinal data which allows change in status to be used in the model demonstrates that those children who had parents whose partnership ended, or whose households moved to a lower household income during the early months of their child’s life were more likely to have moved. Those children in families who increased their income during the second year of a child’s life, or who had experienced a change in partner status, were more likely to have moved during that time period than those children in families whose household income had not changed.

Although challenging to define and measure, residential mobility is an important feature of life for pre-school New Zealanders and as such it will continue to play an important part in future analyses of the Growing Up in New Zealand cohort to determine what influences child developmental trajectories.

Read the full results in our Moving house in the first 1000 days report


Key findings from Now we are two (2014)


The personalities and skills of New Zealand two-year-olds

  • There is significant ethnic diversity within the cohort. One quarter of the Growing Up in New Zealand children are identified as Māori, 20% as Pacific, and one in 6 as Asian. Multiple ethnicities are also very common (almost half of the children).
  • Two thirds of the children knew they were a boy or a girl, and the same proportion used their own name or expressed their independence by typically saying 'do it myself'.
  • Tantrums were the norm for children at two years, with four out of five often expressing themselves this way.
  • Bananas were the most common favourite first food; and saying 'mum', 'mummy' or 'mama' was the most common first word.
  • Over 40% (around 2,500) of our children understand two or more languages at two years old. Te reo Māori was understood by 12% of children in the cohort, and we are looking forward to exploring the use of language further and how this may or may not impact with access to appropriate service and programme delivery.
  • We are starting to see that this new generation of children is a generation of digital natives. Around 80% watched TV or DVDs daily at age two, a greater proportion than the 66% who have had books read to them every day. One in seven had already used a laptop or kids computer system.

The health and safety of New Zealand two-year-olds

  • 86% of children were described as in very good or excellent health.
  • 92% of children were fully immunised at two years of age.
  • Just under half of the cohort had had an ear infection and 14% a skin infection since they were nine months old; tummy bugs and chest infections were also common at this age.
  • 10% of children had been told by a doctor that they have an allergy of some kind, with egg and dairy being the most common allergens.
  • Working smoke alarms were only present in 79% of the children's homes and 38% of children were living in a house without a fully fenced off driveway.
  • Just under one third of children had had a significant accident requiring medical help.
  • One fifth of children had experienced at least one hospital stay by the time they were two years old.

The families and environments of New Zealand two-year-olds

  • 69% were living in a household with two parents present (and no other adults, but possibly other children), and 20% were living in an extended family household (including one or two parents). More children (6%) were living in a household with their parent(s) and non-kin (such as flatmates) than those living with a single parent (without other adults, but possibly with other children; 5%).
  • The proportion of children living in extended family households differed according to their identified ethnicity. Approximately 43% of children who identified as Pacific, 27% of children who identified as Asian and 27% of children who identified as Māori were living in extended family households. This is compared to the 14% of children who identified as European living in an extended family household.
  • Just over half (55%) of the children lived in family owned accommodation at two years of age. The remaining 45% lived in rented accommodation, the majority of which (86%) was private rental accommodation.
  • The families showed high levels of mobility, with around one-third (approximately 2,000) families having moved house since their child was nine months. Despite this high mobility (and the challenge of life with a toddler), 92% of the recruited families continue to be committed to being involved in Growing Up in New Zealand. This commitment reflects how important our families feel it is to be able to contribute their stories to shaping policy and programmes in New Zealand now and into the future.
  • We are seeing changes in the children's environments over time. For example, approximately 300 children and their families were living in more crowded conditions in their homes at two years of age (compared to at nine months), while a similar number are now in less crowded conditions. Around 300 families moved out of their own homes into rental accommodation, while approximately the same number moved into their own homes.
  • While they were recruited from the Auckland, Counties Manukau and Waikato District Health Board regions, the Growing Up in New Zealand children are now living from Kaitaia to Bluff, and many overseas.

Systems and supports for New Zealand two-year-olds

  • Half of the mums of the Growing Up in New Zealand cohort were not in paid work when their children were two, but almost all of the fathers were in paid work at this stage. On average, the mothers in paid work were working 29 hours per week.
  • Over half of the children at two years were in regular early childhood education and care predominantly because of the work and study commitments of their parents but also because their parents were interested in the positive impact that this education may have on the social and language development of their children. When children were not in regular education or care, 10% of their mothers described cost to be a barrier. 56% of children were being looked after regularly each week by someone other than their parents. This had increased from the 35% of children in regular formal or informal early childhood education and care at nine months of age.
  • The average length of time that two year olds were spending in their main child care type was 24 hours per week. The average cost of childcare per week was $160 (median $144). A childcare subsidy was knowingly received by 879 families (23% of the families using childcare).

Read the full results in our Now we are two report


Key findings from Now we are born (2012)


This report introduced, for the first time, the children in the Growing Up in New Zealand cohort.

The babies were born between 3 March 2009 and 14 May 2010, most at term. Over three-quarters (78%) were born in Auckland, Middlemore, or Waikato hospitals. The cohort was made up of 6662 singletons, 89 pairs of twins and two sets of triplets. Males made up 52% (3,526) of the cohort with females making up 48% (3,320).

Nearly one in four (25%) were delivered by caesarean section.

Early infant feeding

  • Breastfeeding was attempted for the vast majority of the Growing Up in New Zealand babies for whom this information was available, with 97% of the babies breastfed at all by nine months of age.
  • Current New Zealand recommendations recommend six months of exclusive breastfeeding. We found exclusive breastfeeding stopped at four months.
  • By nine months of age, the babies had been introduced to a wide range of solid foods, most commonly baby rice, or fruit and vegetables. Plunket was the most commonly reported source of information about infant diet and nutrition for mothers.

Household resources

  • When their babies were nine months old, 54% of the families were living in their own house, with 39% living in private rental, and 7% in public rental accommodation.
  • Families, on average, experienced a drop in income, particularly where previous income was between $100,000 and $150,000 per annum.
  • An unexpected finding was the nearly one-in-five families were receiving income from four or more sources.

Immunisation and health status

  • By the age of nine months, nearly all babies had received their six week (95%) and three month (94%) immunisations. However, coverage had dropped to 90% for the five month immunisations.
  • Most mothers reported that their babies were either in excellent or very good health at the age of nine months.
  • At six weeks of age, almost three-quarters of the babies had been seen by Plunket. Almost 91% of the cohort children received all of their Well Child/Tamariki Ora checks in their first nine months.
  • When primary health care was required, most babies were taken to either a single known doctor (67%) or to one of several doctors at one practice (27%).

Parental health status and health related behaviour

  • When the children were nine months of age, 11% of mothers had symptoms suggestive of postnatal depression compared to 16% of mothers who had symptoms suggestive of depression in late pregnancy. Being a young mother or having high levels of financial or relationship stress increased the chances of a mother having poorer mental health postnatally.
  • Mothers’ alcohol consumption patterns when their children were nine months of age tended to be lower than pre-pregnancy. New Zealand European mothers were more likely to be drinking alcohol than mothers of any other ethnicity.
  • When the babies were nine months of age, 14% of mothers were smoking, and almost one in three of the cohort children were living in a household where someone smoked cigarettes.

Family stability and family environments

  • Approximately nine out of 10 children had parents who had been in a stable relationship over the previous 12 months. Mothers under the age of 20, those without secondary school qualifications, and those living in the most deprived areas were most likely to have experienced a change in their relationship status. Approximately one-quarter of the cohort are growing up in an extended family situation and approximately one in 12 children were being brought up by a mother without a current partner.

Parental work and leave

  • Of those mothers who were in paid employment when pregnant, over 80% had taken some leave. Of these, 30% were still on leave when their babies were nine months old. The leave taken by mothers was most likely to be a combination of paid parental leave (87%), unpaid parental leave (55%) and annual leave (34%). Over half of the mothers who had taken leave used two or three types of leave to cover their time away from employment.
  • Over 2000 of the mothers had returned to work by the time their children were nine months old, with the majority (83%) returning to work for their previous employer.

Child care

  • Returning to work or study was the main reason for why over 2200 of the cohort children spent time (an average of 20 hours per week) being looked after by someone other than their parents at nine months of age. Of those in child care for more than eight hours per week, 40% (685) used an early child care centre such as daycare, Kohanga Reo, or Pacific Islands early childhood centre, 32% were being looked after by their grandparents, and a further 6% were with another relative.
  • The types of main child care providers used at nine months differ notably by ethnicity.

Read the full results in our Now we are born report


Key findings from Before we are born (2010)


Our families are increasingly diverse. They are very different from those of previous generations, and vastly different from those families involved in earlier longitudinal studies in New Zealand.

We interviewed parents while pregnant and began to see more of this diversity and what it means for the next generation of New Zealand children.

Parental relationships and home environments

  • Mothers and fathers are having children later - the average age is 30 and just 60% of all relationships were legally binding.
  • Our children are being born into varied family structures - extended, non-kin and without other adults. One in three are born to at least one parent who did not grow up here and where at least one parent is multilingual. Only one in 20 parents could talk in te reo Māori.

Household resources

  • Four out of every 10 children are born into a family living in our most deprived areas.
  • Almost half of all families are living in rental accommodation when their child is born.
  • Perhaps in part related to housing tenure, our families are highly mobile with over half of all families moving more than twice in the last five years.
  • Both mothers and partners would like to take more leave.
  • Many parents in the most deprived areas were not aware of government support programmes.
  • 60% of pregnancies were planned and over half of the children in the cohort will have older siblings, with the overall size of the families they are born into most likely to have 2 or 3 children including them, rather than 4 or more.

During pregnancy

  • During pregnancy most mothers were able to find a Lead Maternity Carer reasonably quickly in their pregnancy and few had problems registering with their first choice of maternity carer.
  • In terms of behaviours in pregnancy there are an increasing number of guidelines provided to mothers. However, it is clear that not all mothers follow all the guidelines, especially with respect to food and drink. In particular:
    • Over 90% of mothers did make changes to their diet in pregnancy, most frequently avoiding alcohol, caffeine and raw or highly processed foods. However, a considerable number continued to eat these items and consume alcohol in pregnancy.
    • Mothers who reported their pregnancies were unplanned were less likely to take folate in the first trimester of their pregnancy than mothers with a planned pregnancy. However, 16% of all mothers did not take folate at any time before or during their pregnancy.
    • Despite a reduction in smoking rates overall during pregnancy, more than 1 in 10 mothers continued to smoke, with an over-representation of smokers in mothers who identified as Māori and those who lived in the most deprived areas.
    • Mothers who were physically active prior to their pregnancy were most likely to continue to exercise throughout their pregnancy whereas mothers who were not physically active prior to pregnancy were highly unlikely to take up exercise at any time during their pregnancy.


Parental intentions

  • Parental intentions for the ethnic identity of their children were more diverse than the ethnic identities identified by the parents themselves. This largely reflects the mixed ethnicity of the parents and their wishes for their children to identify with all the ethnicities that they identify with.
  • The majority of mothers and partners intend that their child will be breastfed until they are at least 6 months of age. This would translate into higher rates of breastfeeding than we currently see in our population, so there are likely to be mitigating factors that influence future practice.
  • The majority of mothers and partners reported that they intend to fully immunise their child after they are born. Again, the intended rates of immunisation were higher across all groups than the rates we know are currently achieved in our population.

Read the full results in our Before we are born report