SNP Analysis Explains Why Shorter Mothers Have Shorter Pregnancies and Smaller Babies

Published Online August 18, 2015
PLoS Medicine

Shorter women face a higher risk of preterm birth, independent of the genes they pass on to their infants.

This surprising finding, based on pregnancy data from more than 3,400 Nordic women, was published online Aug. 18, 2015, in PLoS Medicine.

Cincinnati Children’s scientists Louis Muglia, MD, PhD, and Ge Zhang, MD, PhD, led the project. Based on a Mendelian randomization analysis, the team found a key link between birth length, weight and height-related single nucleotide polymorphisms (SNPs) transmitted from the mother.

“The explanation for how this happens is unclear,” Muglia says. “It could be related to height affecting the size of the uterus and pelvis, or it could be related to the mother’s metabolic rate and the amount of nutrition she can supply to the growing baby.”

Associations with non-transmitted SNPs were far less significant for birth length and birth weight. However, gestational age was associated with the maternal non-transmitted SNPs.

The findings are important because preterm birth is the leading killer of newborns in the U.S.

“Knowing that a mother’s height can be a factor suggests that optimizing a woman’s growth in childhood or adolescence should decrease the risk for preterm birth later,” Muglia says.

The March of Dimes Prematurity Research Center’s Ohio Collaborative sponsored this study. Researchers plan further studies to determine if the findings apply to low- and middle-income countries, where nutrition-related factors also can restrict growth.