You are here:

1.01 Low birthweight

Why is it important?

Low birthweight (newborns weighing less than 2,500 grams) is associated with premature birth or restricted foetal growth. Low birthweight infants are at a greater risk of dying during their first year of life, and are prone to ill-health in childhood and the development of chronic disease as adults (OECD 2011; Scott 2014). Children with extremely low birthweight (less than 1,000 grams) are also more likely to have psycho-social problems, difficulties at school, and, when they become teenagers, lower achievement on intellectual measures, particularly arithmetic (AIHW 2011d).

Low birthweight is associated with an increased risk of Type 2 diabetes and high blood pressure (AIHW 2011d; Zhang et al. 2013), higher mortality from cardiovascular and kidney diseases in adulthood (White et al. 2010), respiratory diseases in both childhood and adulthood (Hoy et al. 2010), and obesity (Scott 2014).

Risk factors for low birthweight include maternal smoking; socio-economic disadvantage; the weight, age and nutritional status of the mother; excessive alcohol consumption during pregnancy; the number of babies previously born to the mother; poor antenatal care; illness during pregnancy; multiple births; and the duration of pregnancy (see measure 2.21) (AIHW 2011d; Eades et al. 2008; ABS & AIHW 2008; Khalidi et al. 2012).

Findings

Perinatal data for 2011 show that low birthweight was twice as common among babies born to Aboriginal and Torres Strait Islander mothers as among those born to a non-Indigenous mother (12.6% compared with 6%). Over the period 2000 to 2011, excluding multiple births, there was a significant decline in the low birthweight rate among babies born to Indigenous mothers (9%) and there was a narrowing of the gap (for jurisdictions with adequate quality data for trends: NSW, Vic, Qld, WA, SA and NT). The Indigenous low birthweight rate was higher in remote areas (14.5%) than non-remote (12%) (counter to the gradient for non-Indigenous mothers). The low birthweight rate for Indigenous Australians was highest in the NT (16.5%) and lowest in Qld (11.1%).

Most low birthweight babies were born pre-term (67% for babies born to Indigenous mothers and 71% for non-Indigenous mothers). The rate of low birthweight births that were full-term was higher for Indigenous mothers compared with non-Indigenous mothers (33% and 29% respectively). The mean birthweight for infants born to Aboriginal and Torres Strait Islander mothers in 2011 was 3,189 grams compared with 3,374 grams for infants born to other Australian mothers.

A multivariate analysis of perinatal data for the period 2009–11 indicates that, excluding pre-term and multiple births, 51% of low birthweight births to Indigenous mothers were attributable to smoking, compared with 19% for other Australian mothers (see Detailed Analysis). After adjusting for age differences and other factors, it was estimated that if the smoking rate among Indigenous pregnant women was the same as it was for other Australian mothers, the proportion of low birthweight babies could be reduced by 26%. A study in Qld found that, after excluding pre-term and multiple births, 76% of Aboriginal and Torres Strait Islander mothers who gave birth to a low birthweight baby reported smoking during pregnancy (Khalidi et al. 2012).

For Indigenous mothers, the percentage of low birthweight births was highest for those in the 35 years and over age group (19%) and between 12% and 13% for the other age groups (including teenagers). For non-Indigenous mothers, rates were highest among those aged 35 years and over and those under 20 years. There was a gradient by remoteness for low birthweight babies born to Indigenous mothers but, taking account of other factors in the multivariate analysis, remoteness was not significant.

The National Health Performance Authority reported that the percentage of low birthweight babies born to Aboriginal and Torres Strait Islander women varied across regions, ranging from 18% in Gippsland (Vic) to 7% in Frankston-Mornington Peninsula (Vic) (NHPA 2014). In December 2013, national Key Performance Indicators data from Australian Government-funded Indigenous primary health care organisations, showed 13% of Indigenous babies with a recorded birthweight had low birthweight—similar to national results (AIHW 2014w).

International rate comparisons should be treated with caution because of differences in methods used to classify and collect data, and the quality and reliability of data in each country. In New Zealand, 2012 data indicates the proportion of babies born with low birthweight was higher for Maori mothers than other mothers (6.8% compared with 5.8%). Similarly, in Canada, 7% of mothers of Inuit inhabited regions had babies of low birthweight compared with 6% of all mothers (2004–08). In 2012, the proportion of low birthweight babies among American Indian and Alaska Native mothers was 7.6% compared with 8.0% for other American mothers. In Canada, high birthweight was the bigger issue among Aboriginal peoples, linked with maternal diabetes (Smylie et al. 2010). Perinatal data show that in 2012, 1.6% of babies born to Indigenous Australian mothers were of high birthweight (4,500 grams and over), as were 1.7% of babies born to all Australian mothers (AIHW 2014e).

Implications

Recent trends in low birthweight are promising but to continue making gains there needs to be intensified focus on reducing smoking during pregnancy and increasing early and regular access to antenatal care. Analysis of the perinatal data items included in the multivariate analysis suggests that the largest potential improvements in low birthweight outcomes for Aboriginal and Torres Strait Islander mothers will result from lowering rates of smoking during pregnancy.

Perinatal data also indicates that the earlier a woman first accesses antenatal care, the likelihood of having a baby with low birthweight decreases (see measure 3.01). Research confirms that appropriate antenatal care and a healthy environment for the mother can improve the chances that the baby will have a healthy birthweight (Herceg 2005). Maternal nutrition is also an area where more work is needed (Lucas et al. 2014). While improvements in health services such as antenatal and acute care for pregnant women are important to reduce the occurrence of pre-term delivery and improve foetal growth during pregnancy, the reasons for premature delivery are not well understood. Australian governments are investing in a range of initiatives aimed at improving child and maternal health. The Department of Health is coordinating development of National Evidence-Based Antenatal Care Guidelines (Module 2) on behalf of all Australian governments. Module 1 of the Guidelines (published March 2013) covered the first trimester of pregnancy. Module 2 will cover care in the second and third trimesters. The Guidelines have been developed with input from the Working Group for Aboriginal and Torres Strait Islander Women's Antenatal Care to provide culturally appropriate guidance and information for the health needs of Aboriginal and Torres Strait Islander pregnant women and their families. The 2014–15 Federal Budget provides funding of $94 million over three years from July 2015, for theBetter Start to Life approach. This includes:

  • $54 million to increase the number of sites providing New Directions: Mothers and Babies Servicesfrom 85 to 136. These services provide Indigenous families with access to antenatal care; practical advice and assistance with parenting; and health checks for children.
  • $40 million to expand the Australian Nurse–Family Partnership Program (ANFPP)from 3 to 13 sites. The ANFPP aims to improve pregnancy outcomes by helping women engage in good preventive health practices, support parents to improve their child's health and development and help parents develop a vision for their own future, including continuing education and finding work.

The 2014–15 Federal Budget also commits $25.9 million in 2014–15 for a new Indigenous Teenage Sexual and Reproductive Health and Young Parent Support measure. Implemented by states and territories, these services will provide information to young people to make informed decisions about their reproductive health and health behaviours during pregnancy.

In SA, the Aboriginal Family Birthing Program (a partnership model between Aboriginal Maternal Infant Care Workers and midwives) supports Aboriginal women and their families through pregnancy, childbirth and up to 4 weeks postnatally. Since its inception in 2004, SA has seen a slow decrease in low birthweight rates and in the proportion of Aboriginal mothers smoking during pregnancy.

Figure 1.01-1 Low birthweight among liveborn singleton babies, by Indigenous status of mother, (NSW, Vic, Qld, WA, SA and NT), 2000 to 2011
chart showing low birthweight among liveborn singleton babies

Figure 1.01-1 is a time-series graph for the period 2000 to 2011, showing the number of low birthweight babies born, per 100 liveborn singletons, to Aboriginal and Torres Strait Islander mothers compared with non-Indigenous mothers. The graph shows that the rate of low birthweight among singleton babies born to Indignoeus mothers has declined by 9% during the period and there was a narrowing of the gap. The current low birthweight rate is twice as high for babies born to Indigenous mothers than to non-Indigneous mothers.

Source: AIHW/NPESU analysis of National Perinatal Data Collection

Figure 1.01-2 Low birthweight babies per 100 live births, by Indigenous status of mother and state/territory of residence, 2011
chart showing low birthweight babies per 100 live births

Figure 1.01-2 shows the number of low birthweight babies per 100 live births by Indigenous status of the mother and her state/territory of residence for the year 2011. Across all jurisdictions, low birthweight rates are higher for babies born to Indigenous mothers than non-Indigenous mothers. The Indigenous rate was highest in the NT and lowest in Queensland.

Note: ACT and Tas proportions are based on small numbers

Source: AIHW/NPESU analysis of National Perinatal Data Collection

Figure 1.01-3 - Low birthweight babies per 100 live births, by maternal age and Indigenous status, 2011
chart showing low birthweight babies per 100 live births

Figure 1.01-3 shows the rate of low birthweight babies of Aboriginal and Torres Strait Islander mothers and low birthweight babies of non-Indigneous mothers (rate per 100 live births), by age of mother. Data is presented for mothers aged less than 20 years; 20-24 years; 25-29 years; 30-34 years; and 35 years and over. Across all ages, low birthweight rates are higher for babies born to Indigenous mothers than non-Indigenous mothers. Rates are highest for mothers aged 35 and over for babies born to both Indigenous and non-Indigenous mothers.

Source: AIHW/NPESU analysis of National Perinatal Data Collection

Figure 1.01-4 - Low birthweight babies per 100 live births, by Indigenous status of mother and remoteness, 2011
chart showing low birthweight babies per 100 live births

Figure 1.01-4 shows the rate of low birthweight (per 100 live births) among babies born to Aboriginal and Torres Strait Islander mothers compared to non-Indigenous mothers by remoteness category (Major city, inner regional, outer regional, remote and very remote). Across all remoteness areas, low birthweight rates were higher among babies born to Indigenous mothers than non-Indigenous mothers. Rates of low birthweight among babies born to Indigenous mothers increased with remoteness, while for non-Indigenous mothers, rates decreased by remoteness.

Source: AIHW/NPESU analysis of National Perinatal Data Collection