Pre-eclampsia mediates effect of short maternal stature on preterm delivery risk
Women with shorter height are at increased risk of preterm delivery, with the effect of height on the risk partially mediated by pre-eclampsia, a study suggests.
A total of 218,412 women who delivered singleton pregnancies and who had no underlying diseases before pregnancy were assessed for the risk of preterm delivery in relation to height and how the association was mediated by the risk of pre-eclampsia. All women were included in the Japan Society of Obstetrics and Gynecology, a national multicentre-based delivery database among tertiary hospitals.
Results showed that every 5-cm decrement in height was associated with shorter gestational age (−0.30 weeks; 95 percent CI, -0.44 to -0.16) and significantly increased risk of preterm delivery (relative risk, 1.20; 1.13 to 1.27).
Mediation analysis demonstrated that the effect of shorter height on increased risk of preterm delivery, which was attributed to an indirect effect mediated through increased risk of pre-eclampsia, was notable for shorter gestational age (48 percent), as well as risk of preterm delivery (28 percent).
In an analysis stratified by the three subtypes of preterm delivery, the mediated effect was most pronounced for provider-initiated preterm delivery without premature rupture of membranes (PROM; 34 percent) vs spontaneous preterm delivery without PROM (17 percent) or preterm delivery with PROM (0 percent).
Interpretation of the associations between maternal height and pregnancy outcomes has been based upon a mechanistic assumption that maternal height establishes a physical constraint on the intrauterine environment, such that shorter women may have a small uterus size which in turn limits foetal growth. [J Pediatr 2007;150:603–7]
Additionally, adult height may reflect a mother’s cumulative social and nutritional condition over her life course, serving as potential indicator of the persisting biological and/or environmental factors which affect the offspring’s growth in utero. [JAMA 2009;301:1691–701]