Six genetic variables can explain the length of pregnancy and preterm delivery, according to a major international study. The results have been confirmed by an analysis of genetic data from Nordic women.
This is the first major study of hereditary factors related to pregnancy length and preterm delivery, defined as before the 37th week of gestation. A normal pregnancy length is 40 weeks.
"Our findings give us a better understanding of how the duration of the pregnancy is determined and why some deliveries begin too early. Now we need to start studies on how this interacts with, for example, various environmental factors," says Bo Jacobsson, senior researcher at the Norwegian Institute of Public Health and Professor at the Sahlgrenska Academy in Gothenburg, Sweden.
Large research group
Around 40 researchers from the United States and the Nordic countries were led by Professor Jacobsson and Professor Louis Muglia from Cincinnati Children's Hospital and the March of Dimes Prematurity Research Center - Ohio Collaborative, USA. The group discovered six different genetic variants, all of which are related to the length of pregnancy.
Four genes have a clear association with the length of pregnancy, while commonly occurring variants of three of these genes also have an influence on the probability of preterm birth. Variants of two other genes are also linked to pregnancy length. Analyses show that the variants affect maternal genetic material. The findings are published in the New England Journal of Medicine.
Findings confirmed with Nordic health data
When the results of the first study became available, the results were confirmed using genetic data from these Nordic population studies:
- Norwegian Mother and Child Cohort Study (MoBa)
- Danish National Birth Cohort (DNBC)
- Finnish Birth Cohort (FIN)