Maternal Height and Preterm Birth: A Study on 192,432 Swedish Women

What is it about?

We have analysed a rich body of data on Swedish women to better understand the long-term effects of early life events occurring before, during, and after pregnancy. For this study, we worked on data collected between 1991 and 2009 on more than 192,000 Swedish women aged over 18 years. Our objective was to examined the association between maternal height and the likelihood of delivering preterm babies. Main findings: * Short mothers (155 cm tall or shorter) were twice as likely to have a baby born premature at less than 37 weeks of gestation than tall mothers (179 cm or taller) * Among short mothers, 9.4% of babies were born premature and 1.1%very premature (less than 32 weeks of gestation). While for tall mothers, these figures were 4.7% and 0.5%.

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Why is it important?

Our study shows that the chance of having a premature baby rises as the mother’s height decreases. About half of all premature births are ‘spontaneous’, apparently with complex and often unknown causes. But many studies worldwide have shown that maternal height may play a role. What complicates the picture is that there are probably a number of factors involved, such as the mother’s ethnicity and their level of affluence. We don't really know exactly what is behind this association between mothers’ height and spontaneous premature birth, but evidence from other studies suggests it could be anatomical constraints. Short mothers tend to have less space for the babies to grow before birth, and this seems to lead to premature delivery in some women. Based on the mounting evidence, maternal height is one of the factors that needs to be considered when evaluating a woman’s risk of delivering a premature baby.