Height does matter when it comes to giving birth, with the results of a new study showing that short women are twice as likely to have a premature baby than their taller counterparts.
International findings, published in the PLOS ONE journal this month, shows that the shorter a pregnant woman is, the higher her odds are of having a premature baby, while the world's tallest women face the least risk.
The study’s lead author, Dr José Derraik, tells SBS that this study explains that height is just another contributing factor why some women go full-term in pregnancy and others don’t.
“Other risk factors for having a premature birth includes carrying twins and a mother having high blood pressure, an infection or being too thin,” says Dr Derraik.
“Now we can add to that equation, the mother being very short. We know that the two extremes of the height range, women who were very short and very tall, are more and less likely to give birth to a pre-term baby.”
Dr Derraik says although there is no definitive reason why, the most likely reason is that shorter women have smaller pelvises.
“There may be simply a lack of room for the baby to grow and develop inside the mother. So it’s the lack of space that triggers an early birth in some women.”
"We know that the two extremes of the height range, women who were very short and very tall, are more and less likely to give birth to a pre-term baby.”
The study was based on research conducted by New Zealand’s Liggins Institute at the University of Auckland and Uppsala University in Sweden, which examined data on more than 192,000 Swedish women.
It found that almost 9.5 per cent of short mothers, 155 cm tall or shorter, gave birth to a premature baby born before 37 weeks of gestation, while just over one per cent had a very pre-term child, born prior to 32 weeks of gestation.
For tall mothers, 179 cm or taller, these figures were nearly five per cent and 0.5 per cent respectively.
Dr Derraik explains that although the statistics and height range provided in this study are specific to Sweden – whose population is among the tallest in the world – the relationship between a woman’s height and risk of giving birth to a premature baby is the same worldwide.
“The average height of Swedish women is five centimeters taller than average height of women in Australia," he says. "So obviously we are talking about a different population and different height range here.
“But there have been studies done in countries throughout the world and in South East Asia where the average woman is much shorter.
“And they still found that, [relative to what is considered tall or short for that specific country], a country’s shortest women are more likely to give birth to a premature baby.
“So there’s an association between height and premature births that applies everywhere.”
"These findings don’t mean that if you are short you ‘will’ have a premature baby. It just means you have an increased chance of doing so.”
Preterm birth, or premature birth, is a common occurrence worldwide.
An Australian Institute of Health and Welfare report from 2011 states that over eight per cent of all babies born in Australia were pre-term (before 37 completed weeks of gestation).
Newborns born prematurely have higher rates of disabilities like cerebral palsy and death, with morbidity inversely related to gestational age.
As pre-term babies grow and mature, they are also more likely to develop allergies, sight and hearing difficulties and developmental delays depending on how early they are born.
Dr Derraik stresses that the study’s findings are not cause for concern for the world’s shorter women.
“One thing to keep in mind is that this is about ‘likelihood’. These findings don’t mean that if you are short you ‘will’ have a premature baby. It just means you have an increased chance of doing so.”