Mothers
During 2000-02, Indigenous mothers comprised 3.5% of all mothers who gave birth in Australia (table 6.1). The proportion of Indigenous mothers ranged from less than 1% in Victoria to 39% in the Northern Territory. The reported number of Indigenous mothers was highest in Queensland (8,212), followed by New South Wales (6,370), Western Australia (4,631) and the Northern Territory (4,242).
6.1 Indigenous mothers, by state and territory - 2000-02 |
| |
| Indigenous mothers | |
| no. | %(a) | |
| |
New South Wales | 6 370 | 2.5 | |
Victoria | 1 208 | 0.7 | |
Queensland | 8 212 | 5.6 | |
South Australia | 1 288 | 2.5 | |
Western Australia(b) | 4 631 | 6.3 | |
Tasmania | na | na | |
Northern Territory | 4 242 | 38.5 | |
Australian Capital Territory(c) | 177 | 1.3 | |
Australia | 26 128 | 3.5 | |
| |
na not available |
(a) The proportion of Indigenous mothers in each jurisdiction. |
(b) Data may differ from those published by the Department of Health, Government of Western Australia. |
(c) Includes ACT and non-ACT residents who gave birth in the ACT. Among the 177 Indigenous mothers who gave birth, 128 were ACT residents. |
AIHW, National Perinatal Data Collection. |
Fertility rate
The total fertility rate (TFR) provides an estimate of the average number of children that a woman would have throughout her reproductive life if she were to experience the age-specific birth rate in a particular year. In 2003, the TFR for Indigenous women was estimated to be 2.15 babies, compared with 1.76 babies in the total Australian female population (ABS 2004a). Indigenous TFRs vary across the states and territories. The highest Indigenous fertility rate in 2003 occurred in the Northern Territory (2.83 babies), followed by Western Australia (2.32) and Queensland (2.21).
However, the fertility of Indigenous women may be underestimated because of the incomplete identification of Indigenous status in birth registrations. It should also be noted that because a considerable number of Indigenous babies are born to non-Indigenous women, measures of the fertility of Indigenous women inevitably underestimate the impact of these births on the growth of the Indigenous population.
High fertility at younger ages contributes to the relatively high fertility of Indigenous women. Teenage births are more common among Indigenous women than among other women (Sullivan & Lancaster 1999). In 2003, the teenage (15-19 years) birth rate among Indigenous women was more than four times the overall Australian teenage birth rate. Teenage pregnancies are associated with a number of adverse reproductive outcomes such as foetal complications and low birthweight (Fraser et al. 1995). The peak age group for births to Indigenous women was 20-24 years (133 babies per 1,000), compared with 30-34 years for all women (113 babies per 1,000) (graph 6.2).
6.2 Age-specific birth rates(a), by Indigenous status of the mother - 2003
Maternal age
The age of the mother can affect the development of the foetus, with the risk of foetal complications increasing in pregnancies that occur in the teenage years and for mothers over the age of about 35 years (Fraser et al. 1995; Fretts et al. 1995). Maternal age is also associated with perinatal health, with adverse outcomes more likely among younger and older mothers (Laws & Sullivan 2004). The mean age of Indigenous mothers in 2003 was 25 years compared with 31 years for all women (ABS 2004a).
In the National Perinatal Data Collection, 78% of Indigenous mothers who gave birth during the period 2000-02 were under 30 years of age, compared with 49% of non-Indigenous mothers (graph 6.3). The proportion of Indigenous mothers aged less than 20 years was highest in the Northern Territory (31%), followed by Western Australia (23%) and New South Wales (22%) (table 6.4). This compared with only 5% of non-Indigenous mothers in the Northern Territory, 5% in Western Australia and 4% in New South Wales.
6.3 Maternal age, by Indigenous status of the mother - 2000-02
6.4 Births, by maternal age and Indigenous status of the mother - 2000-02 |
| |
| | Under 20 years | 20-34 years | 35 years or over | Total(a) | |
| | no. | % | no. | % | no. | % | no. | % | |
| |
New South Wales | | | | | | | | | |
| Indigenous | 1 379 | 21.6 | 4 530 | 71.1 | 453 | 7.1 | 6 370 | 100.0 | |
| Non-Indigenous | 9 916 | 4.0 | 192 901 | 77.5 | 45 973 | 18.5 | 248 913 | 100.0 | |
Victoria | | | | | | | | | |
| Indigenous | 258 | 21.4 | 844 | 69.9 | 105 | 8.7 | 1 208 | 100.0 | |
| Non-Indigenous | 5 652 | 3.1 | 141 524 | 77.1 | 36 306 | 19.8 | 183 495 | 100.0 | |
Queensland | | | | | | | | | |
| Indigenous | 1 587 | 19.3 | 6 009 | 73.2 | 616 | 7.5 | 8 212 | 100.0 | |
| Non-Indigenous | 7 818 | 5.7 | 108 209 | 78.7 | 21 482 | 15.6 | 137 509 | 100.0 | |
South Australia | | | | | | | | | |
| Indigenous | 265 | 20.6 | 918 | 71.3 | 105 | 8.2 | 1 288 | 100.0 | |
| Non-Indigenous | 2 557 | 5.0 | 39 973 | 78.2 | 8 608 | 16.8 | 51 138 | 100.0 | |
Western Australia(b) | | | | | | | | | |
| Indigenous | 1 082 | 23.4 | 3 271 | 70.6 | 278 | 6.0 | 4 631 | 100.0 | |
| Non-Indigenous | 3 257 | 4.7 | 53 977 | 78.1 | 11 843 | 17.1 | 69 077 | 100.0 | |
Northern Territory | | | | | | | | | |
| Indigenous | 1 304 | 30.7 | 2 712 | 63.9 | 218 | 5.1 | 4 242 | 100.0 | |
| Non-Indigenous | 361 | 5.4 | 5 274 | 78.3 | 1 091 | 16.2 | 6 734 | 100.0 | |
Australian Capital Territory(c) | | | | | | | | | |
| Indigenous | 33 | 18.6 | 131 | 74.0 | 13 | 7.3 | 177 | 100.0 | |
| Non-Indigenous | 444 | 3.3 | 10 433 | 76.8 | 2 710 | 19.9 | 13 588 | 100.0 | |
Australia(d) | | | | | | | | | |
| Indigenous | 5 908 | 22.6 | 18 415 | 70.5 | 1 788 | 6.8 | 26 128 | 100.0 | |
| Non-Indigenous | 30 005 | 4.2 | 552 291 | 77.7 | 128 013 | 18.0 | 710 454 | 100.0 | |
| |
(a) Includes births where the mother's age was not stated. Excludes births to mothers whose Indigenous status was not stated. |
(b) Data may differ from those published by the Department of Health, Government of Western Australia. |
(c) Includes ACT and non-ACT residents who gave birth in the ACT. Among ACT resident Indigenous mothers who gave birth in the ACT, 18.0% were under 20 years, 73.4% were aged 20-34 years and 8.6% were aged 35 years or over. |
(d) Excludes data for Tasmania. |
AIHW, National Perinatal Data Collection. |
Risk factors during pregnancy
Among the risk factors for poor perinatal and child health are alcohol use, tobacco and drug use during pregnancy.
Smoking
Smoking during pregnancy can have a number of detrimental effects on the foetus including low birthweight and spontaneous abortion. Smoking during pregnancy can also have a detrimental effect on the newborn including sudden infant death syndrome, asthma, lower respiratory tract infections, middle ear diseases and stillbirth (Zubrick et al. 2004).
In 2002, data were available from five states and territories: New South Wales, Western Australia, South Australia, the Australian Capital Territory and the Northern Territory. Aboriginal and Torres Strait Islander mothers accounted for 11% of mothers who smoked during pregnancy in these five jurisdictions (Laws & Sullivan 2004).
According to the NSW Midwives data collection, in 2003, 57% of Indigenous mothers in New South Wales reported smoking at some point during pregnancy, compared with 14% of other mothers (NSW Health Department, Centre for Epidemiology and Research 2005).
In the Western Australian Aboriginal Child Health Survey (WAACHS), approximately 49% of mothers of Aboriginal children in Western Australia had smoked or chewed tobacco during pregnancy (table 6.5).
Alcohol consumption
Excessive alcohol intake during pregnancy is associated with an increased risk of alcohol withdrawal symptoms in the baby, foetal alcohol syndrome and perinatal mortality (Zubrick et al. 2004). The Bibbulung Gnareep Solid Kid Study, which involved 274 Aboriginal families from the Perth area, looked at a range of factors influencing poor birth outcomes and poor health in the first 12 months of life. The study found that among other factors, maternal consumption of excess alcohol, namely spirits, during pregnancy was associated with poorer birth outcomes (Eades 2004).
In the WAACHS, the mothers of an estimated 23% of Aboriginal children in Western Australia reported they had consumed alcohol at some point during their pregnancy and an estimated 17% had both smoked and consumed alcohol while pregnant.
Marijuana and other drug use
In the WAACHS, mothers of 9% of Western Australian Aboriginal children had used marijuana during pregnancy. Marijuana usage declined with increasing remoteness, from 11% in metropolitan areas to 2% in areas of extreme (geographic) isolation. Other drugs such as amphetamines and cocaine were reported for less than 1% of mothers.
Effect of substance use during pregnancy on birthweight
The WAACHS estimated the effects of tobacco, alcohol and marijuana use during pregnancy on birthweight by linking survey data to birth records on the Maternal and Child Health Research Data Base (MCHRDB). Mothers who used both alcohol and tobacco during pregnancy were almost twice as likely to have had a low birthweight baby as mothers who did not smoke or drink during pregnancy (15% compared with 8%) (table 6.5).
Overall, tobacco use during pregnancy was associated with a 200 gram reduction in mean birthweight of Aboriginal infants, and tobacco and alcohol use combined was associated with a 250 gram reduction in average birthweight. The effects of low birthweight are discussed in the following section on babies and children.
6.5 Low birthweight Aboriginal babies(a), by maternal substance use during pregnancy - 2001-02 |
| |
| | Alcohol, no tobacco | Tobacco, no alcohol | Both alcohol and tobacco | No alcohol or tobacco | Total | Babies (no.)(b) | |
| |
Mean birthweight | grams | 3 270 | 3 110 | 3 060 | 3 310 | 3 200 | . . | |
Low birthweight | % | 10.2 | 11.0 | 15.4 | 7.8 | 10.3 | 2 180 | |
Proportion of babies | % | 6.0 | 32.1 | 17.3 | 44.6 | 100.0 | 21 200 | |
| |
. . not applicable |
(a) Whose primary carer was their mother. |
(b) Data are weighted estimates and have been derived by weighting the survey sample to reflect the Western Australian Aboriginal population. |
Zubrick et al. 2004. |
Maternal mortality
Between 1997 and 1999, Indigenous status was recorded for 75 (83%) of the 90 maternal deaths during childbirth. Seven deaths were of Aboriginal and Torres Strait Islander mothers, accounting for 9% of the deaths where Indigenous status was known (Slaytor et al 2004). The maternal mortality ratio for Aboriginal and Torres Strait Islander women was approximately 24 per 100,000 confinements in 1997-99 and is more than three times as high as the maternal mortality ratio for other women (7 per 100,000 confinements). These rates must be interpreted with caution due to the very small number of Indigenous maternal deaths.