Mother's height linked to length of pregnancy and baby size
Shorter mothers have genes that increase their chances of giving birth to smaller or prematurely born babies, research has shown.
A study of 3,485 women and infants from Finland, Denmark and Norway found that every centimetre of extra height increased the length, weight and gestational age of newborn babies by 0.05 centimetres, 10 grams and 0.34 days respectively.
Analysis of 697 genetic variants linked to adult height showed that the effects were largely gene-driven.
Inherited genes related to height had a direct impact on a baby's birth weight and length, while duration of pregnancy was determined by conditions in the womb.
A mother's height appeared to be an important factor that influenced the womb environment, said the researchers.
Dr Joe Leigh Simpson, senior vice president for research at the US March of Dimes Foundation that led the study, said: "That a woman's height influences gestational length, independent of the genes she passes on that determine foetal size, is a major finding."
Leading investigator Dr Louis Muglia, co-director of the Perinatal Institute at Cincinnati Children's Hospital Medical Centre, added: "Our findings show that a mother's height has a direct impact on how long her pregnancy lasts.
"The explanation for why this happens is unclear but could depend not only on unknown genes but also on a woman's lifetime of nutrition and her environment."
The findings are reported in the online journal Public Library of Science Medicine.
In their conclusions the authors wrote: "Disentangling these different mechanisms underlying the association between maternal height and pregnancy outcomes is important, as the knowledge may enhance our understanding of the genetic and environmental etiology (origin) of these important pregnancy outcomes and how they impact health."