Preterm birth affects approximately 10 percent of all pregnant people in the United States (Martin JA, Hamilton BE, Osterman MJ, 2015). Globally, 15 million babies are born prematurely. A baby is considered preterm if it is born prior to 37 weeks gestation. Babies who are born too early face increased mortality and morbidity, may spend a long time receiving expensive care in the neonatal intensive care unit and may have lifelong health conditions as a result of their premature birth. The expenses are enormous as is the stress on the family. In locations that do not have full access to robust NICU services, the risk of death as a result of prematurity is high. Prematurity is the leading cause of death in newborns and children under the age of five worldwide (Liu L, Oza S, Hogan D, et al, 2015)
There has been research that indicates the length of gestation and the likelihood of preterm birth has a genetic component. Some studies demonstrate that 30-40% of the differences seen in gestational length can be linked to genetic factors that are primarily associated with the maternal genome.
A new study just published in the New England Journal of Medicine, Genetic Associations with Gestational Duration and Spontaneous Preterm Birth, indicates that there is a link between genome characteristics and the predictability of preterm birth.
This research examined the genome of 43,568 women who were primarily of Northern European descent giving birth to their first child. This is 5 times the size of any previous studies on this topic. This was done in cooperation with 23andMe, a personal genomics and biotechnology company. If there was any medical indication for the preterm delivery, these women were excluded from the data pool and those women carrying more than one baby were also removed from the study. The women self-reported the gestation of their delivery.
Study limitations include the fact that the gestational duration was self-reported. It is thought that 90% of reported gestations lined up with gestational aging estimates done by medical personnel after birth. The data pool was a very homogenous group of Northern European women and more research needs to be done to see if this can be replicated across other ancestries.
Results of genome examination determined that there were six gene regions that may have a role in the length of pregnancy and the timing of birth. One of the regions thought to be involved was related to the cells that were found in the lining of the uterus. It may be possible to determine which medications may be effective on this area of cells.
Additionally, this study revealed that the dietary mineral selenium could be involved in determining who is at risk for preterm birth. Selenium is found in foods such as Brazil nuts, yellowfin tuna, halibut, sardines, grass-fed beef, turkey, beef liver, chicken, egg, and spinach. This link could mean that there may be a low-tech, simple solution that would involve providing selenium supplements to pregnant people. If this link is confirmed, it has the potential to save many lives.
Funding for this study was provided by the March of Dimes who works globally to prevent premature birth and birth defects. They released a press release on this new study. According to the March of Dimes - there are several key implications:
- This is a beginning point. The six gene areas identified by the project serve as a launching platform for deeper research, some of which has already begun. Potential diagnostic tests, new medications, improved dietary supplements or other changes that could help more women have full-term pregnancies will require several more years of study, the authors say.
- One of the gene areas identified suggests that cells within the lining of the uterus play a larger-than-expected role in the length of pregnancy, which in turn provides a new target for medications to help prevent preterm birth.
- Another newly identified gene area raises important questions about how a lack of selenium—a common dietary mineral found in some nuts, certain green vegetables, liver and other meats—might affect preterm birth risk. People living in regions with low selenium in soil and diet, and people in the U.S. who live in low-income “food deserts” are most at risk of having a lack of selenium in their diets.
Prematurity is a serious problem that affects families all around the globe. Learning what factors influence who may be at risk of delivering too early can be a significant contribution to reducing the impact of premature birth. That will be invaluable in determining what might be an effective treatment for preventing these early births. Having information on the gene areas responsible can pave the way for research on what might change the impact of these areas to reduce the risk of premature birth. I look forward to learning more and seeing what additional research is implemented to help babies at risk of prematurity make it to full term and be born healthy and strong.
Liu L, Oza S, Hogan D, et al. Global, regional, and national causes of child mortality in 2000-13, with projections to inform post-2015 priorities: an updated systematic analysis. Lancet 2015;385:430- 40.
Martin JA, Hamilton BE, Osterman MJ. Births in the United States, 2014. NCHS Data Brief 2015;216:1-8.
Zhang, G., Feenstra, B., Bacelis, J., Liu, X., Muglia, L. M., Juodakis, J., . . . Muglia, L. J. (2017). Genetic Associations with Gestational Duration and Spontaneous Preterm Birth.New England Journal of Medicine. doi:10.1056/nejmoa1612665