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Tier 1 - Health status and outcomes

1.01 Low birthweight

Key facts

Why is it important?

Low birthweight (newborns weighing less than 2,500 grams) is associated with premature birth or restricted fetal growth. Low birthweight infants are at a greater risk of dying during their first year of life (see measure 1.21 Perinatal mortality), and are prone to ill-health in childhood and the development of chronic disease as adults, including cardiovascular disease, high blood pressure, kidney disease and type 2 diabetes (Arnold et al. 2016; Hoy & Nicol 2010; Luyckx et al. 2013; OECD 2011; Scott 2014; White et al. 2010; Zhang et al. 2014).

Risk factors for low birthweight include maternal smoking and alcohol consumption during pregnancy (see measure 2.21 Health behaviours during pregnancy); poor antenatal care (see measure 3.01 Antenatal care); the weight, age and nutritional status of the mother; the number of babies previously born to the mother; illness during pregnancy; pre-existing high blood pressure and diabetes; multiple births; socioeconomic disadvantage; and experiencing three or more social health issues during pregnancy (AIHW 2011; ABS & AIHW 2008; Brown et al. 2016; Eades et al. 2008; Khalidi et al. 2012; Sayers & Powers 1997).

The recently established National Agreement on Closing the Gap has identified the importance of ensuring Aboriginal and Torres Strait Islander children are born healthy and strong with a specific outcome, target and indicators to direct policy attention and monitor progress in this area. Reporting arrangements for the new agreement are being established. The data presented in this report predates the establishment of the Agreement.

Burden of disease

In 2011, infant and congenital conditions contributed 6% of the total disease burden for Indigenous Australians. The leading cause of burden was pre-term or low birthweight complications, accounting for 29% of infant and congenital burden. The burden for pre-term or low birthweight complications was higher for male babies (60%) (AIHW 2016).

Findings

What does the data tell us?

Data in the Findings section of this measure refer to singleton live born births based on the Indigenous status of the mother, unless stated otherwise. Singleton births are the birth of only one baby during a pregnancy. Multiple births are associated with low birthweight and as a result should be excluded from analysis on low birthweight (AIHW 2020).

Perinatal data for 2017 singleton births (not including multiple births) shows that Indigenous mothers were twice as likely to have a low birthweight live born baby compared with non‑Indigenous mothers—11% of babies born to Indigenous mothers (1,415 babies) and 5% of babies born to non-Indigenous mothers (13,768 babies), respectively (Table D1.01.1).

Based on the Indigenous status of the baby, the low birthweight rate was 10% for Indigenous babies (1,615 babies) compared with 5% (13,380 babies) for non‑Indigenous babies (Table D1.01.13).

Between 2000 and 2017, the low birthweight rate for singleton babies born to Indigenous mothers declined by 15% (from 11.7% in 2000 to 10.7% in 2017), while the rate for babies born to non-Indigenous mothers increased by 5% (from 4.5% in 2000 to 4.9% in 2017). From 2007 to 2017, the low birthweight rate for Indigenous mothers declined by 7% (Table D1.01.2, Figure 1.01.1). This analysis was based on the Indigenous status of the mother of singleton live-born babies in the combined six jurisdictions with data of adequate quality (New South Wales, Victoria, Queensland, Western Australia, South Australia and the Northern Territory).

Figure 1.01.1: Low birthweight live born singleton babies, by Indigenous status of the mother, NSW, Vic, Qld, WA, SA and the NT combined, 2000 to 2017

This line chart shows that the proportion of low birthweight, live born singleton babies born to Indigenous mothers decreased from 11.7% in 2000 to 10.7% in 2017, while the proportion of babies born to non-Indigenous mothers kept steady, ranging from 4.4% to 4.9%.

Source: Table D1.01.2. AIHW analysis of the National Perinatal Data Collection.

In 2017, the low birthweight rate for singleton babies born to Indigenous mothers varied by jurisdiction; the rate was lowest in New South Wales (9%) and highest in the Northern Territory (14%) (Table D1.01.1, Figure 1.01.2).

Figure 1.01.2: Low birthweight live born singleton babies, by Indigenous status of the mother and jurisdiction, 2017

This bar chart shows that, overall the proportion of low birthweight babies was 10.7% for live born singleton babies born to Indigenous mothers, and 4.9% for babies born to non-Indigenous mothers. The highest proportion was in the Northern Territory (13.9%), followed by the Australian Capital Territory (13.5%), and was lowest in New South Wales (9.0%); for babies born to non-Indigenous mothers, the highest was in Tasmania (6.3%), and lowest in the Northern Territory (4.3%).

Source: Table D1.01.1. AIHW analysis of the National Perinatal Data Collection.

In 2017, the rate of low birthweight babies born to Indigenous mothers varied by remoteness, with the lowest rate in Major cities and Inner regional areas (both 10%) and the highest in Very remote areas (13%) (Table D1.01.7, Figure 1.01.3).

Figure 1.01.3: Low birthweight live born singleton babies, by Indigenous status of the mother and remoteness, 2017

This bar chart shows that, the proportion of live born singleton low birthweight babies  born to Indigenous mothers increased with remoteness from around 10% in Major cities and Inner regional areas to 12.8% in Very remote areas. For babies born to non-Indigenous mothers, the proportion was lowest in Remote  areas (4.1%) and similar throughout other areas (around 5%).

Source: Table D1.01.7. AIHW analysis of the National Perinatal Data Collection.

Average birthweight

In 2017, the average birthweight for singleton babies born to Indigenous mothers was 3,234 grams compared with 3,365 grams for non‑Indigenous babies. Between 2000 and 2017, the average birthweight for babies born to Indigenous mothers increased significantly by 2.1%, from 3,196 grams to 3,234 grams. From 2007 to 2017, the average birthweight for babies born to Indigenous mothers increased significantly (by 1.3%) (Table D1.01.5, Figure 1.01.4).

Figure 1.01.4: Average birthweight of live born babies, by Indigenous status of the mother, NSW, Vic, Qld, WA, SA and NT, 2000 to 2017

This line chart shows that the average birth weight for babies born to Indigenous mothers increased from 3,196 grams in 2000 to 3,234 grams in 2017, and that babies born to Indigenous non-mothers, decreased from 3,417 to 3,365 grams.

Source: Table D1.01.5. AIHW analysis of the National Perinatal Data Collection.

Babies born pre-term with low birthweight

Low birthweight is closely associated with pre-term births (gestational age before 37 completed weeks) (AIHW 2020). Of all the 16,778 Indigenous live born babies in 2017 (including multiple births), 12% were born pre-term, compared with 8% of non-Indigenous babies (Table D1.01.13). Pre‑term babies accounted for 70% (1,184) of low birthweight babies born to Indigenous mothers, similar to babies born to non‑Indigenous mothers (71%, or 13,043 babies) (Table D1.01.4). Based on the Indigenous status of the baby, pre-term babies accounted for 69% (1,335) of Indigenous low birthweight babies compared with 70% (12,596) of non-Indigenous low birthweight babies (Table D1.01.13).

Maternal age and low birthweight babies

In 2017, the percentage of low birthweight singleton births was highest for Indigenous mothers aged 35 and over (13%) and less than 20 (12%), and for non-Indigenous mothers aged under 20 (8%) (Table D1.01.7, Figure 1.01.5).

Figure 1.01.5: Low birthweight live born singleton babies, by Indigenous status of the mother and maternal age, 2017

This bar chart shows that for Indigenous mothers the proportion of live born singleton babies that had a low birthweight was highest for those aged 35 or over (12.8%) and those aged 19 or under (12%). For non-Indigenous mothers the proportion was highest for those aged 19 or under (8.1%) and those aged between 20 and 24 (5.8%).

Source: Table D1.01.7. AIHW analysis of the National Perinatal Data Collection.

Smoking and low birthweight babies

In 2017, including multiple births, live born babies of Indigenous mothers who smoked during pregnancy were 1.5 times as likely to be born pre-term as babies born to non-Indigenous mothers who smoked (18% and 12% respectively), after adjusting for differences in age structures between the two populations (see measure 2.21 Health behaviours during pregnancy) (Table D2.21.4).

In 2017, Indigenous mothers who smoked during pregnancy were also 1.5 times as likely to have singleton babies with low birthweight than non-Indigenous mothers who smoked during pregnancy (15% and 10% respectively). For mothers who did not smoke during pregnancy, rates of low birthweight were 7% for Indigenous mothers and 4% for non-Indigenous mothers (Table D1.01.7, Figure 1.01.6).

A multivariate analysis of perinatal data for singleton births for the period 2015–2017 indicates that, for full-term births, 47% of low birthweight births to Indigenous mothers were attributable to smoking, compared with 12% for non-Indigenous mothers (Table D1.01.8). After adjusting for differences in the age structure between the two populations, and other factors, it was estimated that if the smoking rate among Indigenous pregnant women was the same as that of non-Indigenous mothers, the proportion of low birthweight babies could be reduced by 33% (Table D1.01.9).

Maternal smoking and birth outcomes such as low birthweight and pre-term birth are key drivers of change in infant and child mortality. For more information see Closing the Gap Targets: 2017 Analysis of Progress and Key Drivers of Change.

Antenatal care

The 2014–15 National Aboriginal and Torres Strait Islander Social Survey showed that mothers with low birthweight babies were less likely to have had regular check-ups during their pregnancy than those who had babies who were not of low birthweight (84% and 98% respectively) (Table D2.21.8).

Perinatal data from 2017 showed that, Indigenous mothers who had antenatal care visits during pregnancy were less likely to have a singleton live born baby of low birthweight than those who did not have any antenatal care visits (10% compared with 30%) (Table D3.01.14).

Indigenous mothers who attended five or more antenatal visits during pregnancy were less likely to have a low birthweight singleton baby (8%), compared with Indigenous mothers who had two to four antenatal visits (15%) or Indigenous mothers who had 1 antenatal visit (24%) (Table D3.01.5).

Low birthweight and selected characteristics

Babies born to Indigenous mothers living in the most disadvantaged socioeconomic group (1st quintile) (12%) were more likely to be low birthweight than those born to Indigenous mothers living in the least disadvantaged socioeconomic group (5th quintile) (9%). Babies born to Indigenous mothers who were underweight (22%) were more likely to be low birthweight than those born to Indigenous mothers of normal weight (12%), overweight (9%) or obese (6%). Rates of low birthweight were also higher than average for babies of Indigenous mothers who had pre-existing hypertension (22%) and pre-existing diabetes (17%) (Table D1.01.7, Figure 1.01.6).

Figure 1.01.6: Low birthweight live born singleton babies born to Indigenous mothers, by selected maternal characteristics, 2017

This bar chart shows that 22% of Indigenous mothers who were underweight or had pre-existing hypertension delivered a live born singleton baby who was underweight. This chart also shows higher proportions of low birthweight babies for Indigenous mothers with pre-existing diabetes (17%) Indigenous mothers who smoked (15%).

Source: Table D1.01.7. AIHW analysis of the National Perinatal Data Collection.

High birthweight

Perinatal data showed that in 2017, based on the Indigenous status of the baby, rates of high birthweight in singleton births (4,500 grams and over) were similar for Indigenous babies (1.3%) and non-Indigenous babies (1.2%) (Table D1.01.14).

International birthweight comparisons

In Australia in 2017, including all live births, 13% of babies born to Indigenous mothers were born with low birthweight compared with 6.4% of babies born to non-Indigenous mothers. In New Zealand, 2016 data indicated that the proportion of babies born with low birthweight was higher for Māori mothers than Other mothers (6.5% compared with 5.7%). Similarly, in Canada, 7.2% of mothers of Inuit inhabited regions had babies of low birthweight compared with 6.1% of all mothers (2009–2013). In 2018, the proportion of low birthweight babies among American Indian or Alaska Native mothers was comparable to Other American mothers (8.0 compared with 8.3%) (Table D1.01.10). In Canada, high birthweight was the bigger issue among Aboriginal peoples, linked with maternal diabetes (Smylie et al. 2010). Note that international rate comparisons should be treated with caution because of the differences in methods used to classify and collect data, and the variances in the quality and reliability of the data available in each country.

What do research and evaluations tell us?

Babies born with low birthweight have been found to experience life-long and broad ranging health complications. Studies have identified that low birthweight is associated with:

Children with extremely low birthweight (less than 1,000 grams) are more likely to face psycho‑social problems and difficulties at school. It has been found that teenagers who had extremely low birthweight are less likely to do well at school and experience lower achievements on intellectual measures, particularly arithmetic (AIHW 2011).

A complex range of maternal health and social and demographic factors can contribute to low birthweight:

  • A multivariate analysis of perinatal data for 2012–2014 indicated that, excluding pre-term and multiple births, 51% of low birthweight births to Indigenous mothers were attributable to smoking, 21% to area-level socioeconomic status (SES), and 5% to remoteness (AIHW 2018).
  • Maternal exposure to domestic violence has been found to be associated with significantly increased risk of low birth weight and pre-term birth (Coker et al. 2004; Shah & Shah 2010; Webster 2016).

Other maternal health factors that contribute to low birthweight include excessive alcohol consumption during pregnancy, nutritional status, substance abuse, low or high body mass index, and maternal age (Howson et al. 2012; Kildea et al. 2017; Kramer et al. 2001; Moutquin 2003; Poulsen et al. 2015).

A suite of evaluations have been published across Australia on programs to improve the delivery of antenatal services to Indigenous Australian women with the intent of improving birth outcomes. The Clinical Practice Guidelines—Pregnancy Care (2019 edition) outlines evidence of successful models of care from these evaluations specifically tailored for Indigenous Australian women. This includes culturally appropriate and safe care as well as continuity of care; collaboration between midwives and Indigenous health workers; and the role of family members such as grandmothers in attending antenatal care sessions and positively influencing maternal healthy lifestyle behaviours during pregnancy (DoH 2018). These models of care have been shown to have quantifiable improvements in antenatal care attendance, pre-term births, birth outcomes, perinatal mortality, and breastfeeding practice. However, significant reductions in low birthweight are yet to be demonstrated.

Many Indigenous Australian women do not have access to these specific programs and rely on mainstream health services such as general practitioners and hospital clinics (Clarke & Boyle 2014). As such, the Guidelines also urge the importance for mainstream services to embed cultural competence into continuous quality improvement activities for services.

Implications

The rate of low birthweight among babies born to Indigenous Australian mothers has persisted since 2010, despite an intensified focus on reducing smoking during pregnancy and increasing early and regular access to antenatal care. Maternal nutrition is also an area in which more work is needed (Lucas et al. 2014). While caution is required when making comparisons with international data, rates of low birthweight babies born to Indigenous mothers in Australia appear to be higher compared with those in New Zealand, the United States and Canada.

The multivariate analysis of perinatal data suggests that large improvements will result from lowering the rate of smoking during pregnancy. The inclusion of alcohol consumption during pregnancy would be a useful addition to the National Perinatal Data Collection to aide the analysis of maternal risks and birth outcomes.

Perinatal data indicate that the earlier an expectant mother first accesses antenatal care, the lower the likelihood of having a baby with low birthweight (see measure 3.01 Antenatal care). Research shows that appropriate antenatal care (including improved management of high-risk pregnancies) and a healthy environment for the mother can improve the chances that the baby will have a healthy birthweight (Herceg 2005; Taylor et al. 2013).

Strategies addressing potentially modifiable risk factors for pre-term birth, low birthweight and small for gestational age babies should be an important focus of antenatal care delivery. There is a need for early, high quality, culturally responsive, and women‑centred care delivered for Indigenous Australian women in Major cities, Regional and Remote areas. A recent systematic review focused on improving the delivery of effective health services for Indigenous Australians, including antenatal care, found improved outcomes when services were designed specifically for and with Indigenous Australians (Gwynne et al. 2019). This finding supports the important role of Aboriginal Community Controlled Health Services in the design and delivery of services.

Australian governments are investing in a range of initiatives aimed at improving child and maternal health. Detailed descriptions are included in the Policies and strategies section and include the Australian Nurse-Family Partnership Program, New Directions, Healthy for Life, Better Start to Life, Connected Beginnings, and the National Tobacco Campaign’s, Quit for You, Quit for Two. See also measures 3.01 Antenatal care and 2.21 Health behaviours during pregnancy, particularly smoking.

The prevailing assumption in this policy space has been that lowering the rate of smoking during pregnancy and other maternal risk factors, and improving antenatal care access, would lead to reductions in low birthweight. However, significant reductions in low birthweight remain to be seen. Further research and evaluation of the coverage and effectiveness of existing strategies and programs are needed to understand why improvements in smoking during pregnancy and antenatal care attendance have yet to be translated into significant reductions in the rate of low birthweight at a population level. Further research should also focus on the type of antenatal service or intervention and model of care provided and on identifying ways to better target services particularly for vulnerable Indigenous women at risk of family and domestic violence.

The association between low birthweight and chronic disease in adult life suggests improvements in the rate of low birthweight are essential for improving health outcomes well into the future.

The new National Agreement on Closing the Gap was developed in partnership between Australian governments and the Coalition of Aboriginal and Torres Strait Islander Peak Organisations. The Agreement has recognised the importance of ensuring Aboriginal and Torres Strait Islander children are born healthy and strong by establishing the following outcome and target to direct policy attention and monitor progress:

  • Outcome 2 — Aboriginal and Torres Strait Islander children are born healthy and strong.
    • Target — By 2031, increase the proportion of Aboriginal and Torres Strait Islander babies with a healthy birthweight to 91 per cent.

The policy context is at Policies and strategies.

References

  • ABS & AIHW 2008 (Australian Bureau of Statistics & Australian Institute of Health and Welfare) 2008. The health and welfare of Australia's Aboriginal and Torres Strait Islander peoples 2008. Canberra: ABS & AIHW.
  • AIHW (Australian Institue of Health and Welfare) 2011. Headline indicators for children's health, development and wellbeing 2011. Canberra: AIHW.
  • AIHW 2016. Australian Burden of Disease Study: impact and causes of illness and death in Aboriginal and Torres Strait Islander people 2011. Australian Burden of Disease Study series 6. Cat. no. BOD 7. Canberra: AIHW.
  • AIHW 2018. Closing the Gap targets: 2017 analysis of progress and key drivers of change. Canberra: AIHW.
  • AIHW 2020. Australia’s mothers and babies 2018: in brief. Perinatal statistics series no. 36. Cat. no. PER 108. Canberra: AIHW.
  • Arnold L, Hoy W & Wang Z 2016. Low birthweight increases risk for cardiovascular disease hospitalisations in a remote Indigenous Australian community – a prospective cohort study. Australian & New Zealand Journal of Public Health 40:S102-S6.
  • Brown SJ, Mensah FK, Ah Kit J, Stuart-Butler D, Glover K, Leane C et al. 2016. Aboriginal Families Study Policy Brief No 4: Improving the health of Aboriginal babies. Melbourne: MCRI.
  • Clarke M & Boyle J 2014. Antenatal care for Aboriginal and Torres Strait Islander women. Australian Family Physician 43:20-4.
  • Coker AL, Sanderson M & Dong B 2004. Partner violence during pregnancy and risk of adverse pregnancy outcomes. Paediatric and perinatal epidemiology 18:260-9.
  • DoH (Australian Government Department of Health) 2018. Clinical Practice Guidelines: Pregnancy Care. Canberra: Australian Government Department of Health.
  • Eades S, Read AW, Stanley FJ, Eades FN, McCaullay D & Williamson A 2008. Bibbulung Gnarneep ('solid kid'): causal pathways to poor birth outcomes in an urban Aboriginal birth cohort. Journal of Paediatrics & Child Health 44:342-6.
  • Gwynne K, Jeffries T & Lincoln M 2019. Improving the efficacy of healthcare services for Aboriginal Australians. Australian Health Review 43:314-22.
  • Herceg A 2005. Improving health in Aboriginal and Torres Strait Islander mothers, babies and young children: a literature review. (ed., Office for Aboriginal and Torres Strait Islander Health, Department of Health and Ageing). Canberra: OATSIH.
  • Hovi P, Anderson S, Eroksson J & Jarvenpaa A 2007. Glucose regulation in young adults with very low birthweight. New England Journal of Medicine 356:2053-63.
  • Howson C, Kinney M & Lawn J 2012. The global action report on preterm birth, born too soon. Geneva: March of Dimes, Partnership for Maternal, Newborn and Child Health, Save the Children. World Health Organisation.
  • Hoy W & Nicol J 2010. Birthweight and natural deaths in a remote Australian Aboriginal community. The Medical Journal of Australia 192:14-9.
  • Khalidi N, McGill K, Houweling H, Arnett K & Sheahan A 2012. Closing the Gap in Low Birthweight Births between Indigenous and Non-Indigenous Mothers, Queensland. (ed., Health Statistics Centre, Queensland Health). Brisbane: QLD Health.
  • Kildea SV, Gao Y, Rolfe M, Boyle J, Tracy S & Barclay LM 2017. Risk factors for preterm, low birthweight and small for gestational age births among Aboriginal women from remote communities in Northern Australia. Women and Birth 30:398-405.
  • Kramer MS, Goulet L, Lydon J, Séguin L, McNamara H, Dassa C et al. 2001. Socio‐economic disparities in preterm birth: causal pathways and mechanisms. Paediatric and perinatal epidemiology 15:104-23.
  • Lucas C, Charlton KE & Yeatman H 2014. Nutrition advice during pregnancy: do women receive it and can health professionals provide it? Maternal & Child Health Journal 18:2465-78.
  • Luyckx VA, Bertram JF, Brenner BM, Fall C, Hoy WE, Ozanne SE et al. 2013. Effect of fetal and child health on kidney development and long-term risk of hypertension and kidney disease. The Lancet 382:273-83.
  • Moutquin J-M 2003. Socio-economic and psychosocial factors in the management and prevention of preterm labour. BJOG: an international journal of obstetrics and gynaecology 110:56-60.
  • OECD 2011. Health at a Glance 2011:OECD Indicators. Paris: OECD Publishing.
  • Phillips D 2006. Birth weight and adulthood disease and the controversies. Fetal and Maternal Medicine Review 17:205-27.
  • Poulsen G, Strandberg‐Larsen K, Mortensen L, Barros H, Cordier S, Correia S et al. 2015. Exploring Educational Disparities in Risk of Preterm Delivery: A Comparative Study of 12 E uropean Birth Cohorts. Paediatric and perinatal epidemiology 29:172-83.
  • Sayers S & Powers J 1997. Risk factors for aboriginal low birthweight, intrauterine growth retardation and preterm birth in the Darwin Health Region. Australian & New Zealand Journal of Public Health 21:524-30.
  • Scott JA 2014. Chronic disease profiles in one high risk Indigenous community: a comparison of chronic disease profiles after a 10 year follow up and the relationship between birth weight and chronic disease morbidity and mortality. The University of Queensland.
  • Shah PS & Shah J 2010. Maternal exposure to domestic violence and pregnancy and birth outcomes: a systematic review and meta-analyses. Journal of Women's Health 19:2017-31.
  • Smylie J, Crengle S, Freemantle J & Taualii M 2010. Indigenous birth outcomes in Australia, Canada, New Zealand and the United States–an overview. The Open Women's Health Journal:7.
  • Tappy L 2006. Adiposity in children born small for gestational age. International Journal of Obesity 30:36-40.
  • Taylor LK, Lee YY, Lim K, Simpson JM, Roberts CL & Morris J 2013. Potential prevention of small for gestational age in Australia: a population-based linkage study. BMC Pregnancy & Childbirth 13:210.
  • Webster K 2016. A preventable burden: Measuring and addressing the prevalence and health impacts of intimate partner violence in Australian women Australia's National Research Organisation for Women's Safety, Compass.
  • White A, Wong W, Sureshkumur P & Singh G 2010. The burden of kidney disease in indigenous children of Australia and New Zealand, epidemiology, antecedent factors and progression to chronic kidney disease. Journal of Paediatrics & Child Health 46:504-9.
  • Zhang Z, Kris-Etherton PM & Hartman TJ 2014. Birth weight and risk factors for cardiovascular disease and type 2 diabetes in US children and adolescents: 10 year results from NHANES. Maternal & Child Health Journal 18:1423-32.

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