Research from Perth's The Kids Research Institute Australia has shown that a short time interval between pregnancies may be less of a risk factor for preterm birth and low birth weight than previously thought.
The findings of this study have been published in the prestigious international journal, The BMJ.
Other studies have reported that pregnancies starting less than two years after a previous birth are more likely to result in preterm birth and low birth weight. It has been thought that adequate birth spacing is required to give mothers time to recover from the physical impacts of pregnancy.
The Kids Research Institute Australia researchers took a new approach to analysing the effect of the spacing between pregnancies. Instead of comparing the births from different mothers, they compared the births of individual mothers who had three or more births. By focussing on an effect within mothers rather than between mothers, this method removed the effect of risk factors which predispose a mother's children to preterm birth or low birth weight.
Using data from over 40,000 Western Australian mothers between 1980 and 2010, they found that a short interval between pregnancies did not affect the risk of preterm birth or low birth weight.
Epidemiologist Dr Stephen Ball said the results suggest that increased risk of preterm birth and low birth weight is not caused by short intervals between pregnancies, but by other factors which tend to be more common among mothers with closely spaced pregnancies.
"There may be more effective ways of reducing the risk of poor birth outcomes than by avoiding a short interval between pregnancies - for example, by eating well, maintaining a healthy weight, avoiding smoking and alcohol consumption, and seeking adequate medical care," Dr Ball said.
Co-author Professor Fiona Stanley said the results challenge existing thinking about the effect of short intervals between pregnancies. "Based on the results of our study, mothers who fall pregnant again within two years should be reassured about the effects of the short interval."
However, Professor Stanley cautioned that this is the first study to look at birth spacing in this way. "The World Health Organization recommends mothers wait two years between the birth of one child and starting to try for the next," Professor Stanley said. "Our results are based on population averages, and there may be some situations where it is important to allow a sufficient time to recover between pregnancies."
The research team is hoping to build on this study by examining whether birth spacing remains an important issue for women from disadvantaged backgrounds, who may be more heavily impacted by the physical stresses of pregnancy.
Watch the video abstract
Listen on ABC's Health Report
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