What causes premature birth? Emerging role of genetics

It is challenging enough to deliver a baby without having to worry about words like premature birth, and spontaneous preterm labour. Unfortunately, premature births account for up to 12% of infant (1-12 months old) deaths in North America, and 70% of ALL neonatal (< 28 days old) deaths1. These are sobering numbers for any mother or father thinking about starting a family, but it also means that a significant amount of research has gone into understanding the causes of premature birth, and the emerging role that our own genetics can play as a substantial risk factor.
What causes premature birth? Emerging role of genetics

What causes premature birth, and what is spontaneous preterm labour?

Premature births occur when a baby is delivered before 37 weeks (~9 months) of gestation and it is the leading cause of infant mortality in developed countries. A majority of these deaths occur due to babies who are born ‘early preterm’ at less than 32 weeks (8 months) of gestation. There are many causes of ‘early preterm’ labour but an overwhelming number of them are a result of spontaneous preterm labour, which is caused by the spontaneous rupture of the fetal membrane or the sudden onset of uterine contractions. So in essence spontaneous preterm labour is a specific subcategory of premature birth.

How does spontaneous preterm labour affect my baby?

Premature births caused by spontaneous preterm labour can result in serious health problems and can decrease the survival chances of your baby. It can also cause long-term neurological problems and mental disabilities.

In general, the more premature the baby, the higher the risk that the baby will have of developing some form of health abnormality, and this decreases the baby’s overall chances of survival.

Are we any closer to predicting the risk of premature births, or spontaneous preterm labour?

Several studies have uncovered a wide variety of non-genetic risk factors that cause spontaneous preterm labour, which range from maternal/fetal stress to uterine inflammation2. This diversity makes it difficult to accurately predict the risk of spontaneous preterm labour associated with any pregnancy.

Encouragingly, family and twin studies have suggested that genetics play a substantial role in predicting the probability of premature births. Most of these studies focused on the role of maternal genes, but a recent study decided to go the opposite direction and explore whether paternal genes had any effect on the probability of preterm births3. Surprisingly, the researchers found that paternal genes actually play a larger role than anticipated in determining the likelihood of premature deliveries. In fact, this study actually goes further to suggest that maternal genes DO NOT contribute to the risk of premature birth.

As it turns out, DNA variation in paternal genes particularly those involved in the immune response (gene for the major histocompatibility complex), and white-matter diseases (genes for certain RNAses) affect the gestational age of newborns and determine the time a fetus stays in the womb. This is a very new and exciting finding that paves the way for future research studying the role of other paternal genes involved in predicting the risk of premature birth!

So what does this mean for me?

The first step is to realize that genetics not only plays a role in predicting spontaneous preterm labour as suggested in the studies we mentioned in this blog post, but that it can also affect fertility and pregnancies in general. For example, complications such as multiple miscarriages have also been shown to have a genetic link.

Therefore, you and your physician should consider genetic testing to identify potentially harmful gene variations you may be carrying, which can help you make an informed decision regarding your fertility options. Ultimately knowledge is power, and services such as GeneYouIn’s PregnaSeq can help you determine any genetic markers that might complicate your pregnancy.

If you would like more information regarding when to consider fertility treatment then please read our blog post about fertility problems and when to ask for treatment.

As always, please share this article with your friends and family if you’ve found it to be useful, and make sure to follow GeneYouIn on Facebook and Twitter, or register for our newsletter to stay up to date on all the latest research in personalized medicine!


  1. Blencowe, H., Cousens, S., Oestergaard, MZ., Chou, D., Moller, AB., Narwal, R., Adler, A., Garcia, CV., Rohde, S., Say L., and Lawn, JE. (2012) National, regional, and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications. Lancet (379) 2162-2172.
  2. Goldenberg, RL., Culhane, JE., and Romero, R. (2008) Epidemiology and causes of preterm birth. Lancet (317) 75-84.
  3. Zhang, H., Balwin, DA., Bukowski, RK., Parry. S., Xu, Y., Song, C., Andrews, WW., Saade, GP., Esplin, MS., Sadovsky, Y., Reddy, UM., Ilekis, J., Varner, M., and Biggio, JR (2015) A Genome-Wide Association Study of Early Spontaneous Preterm Delivery. Genetic Epidemiology 1-10.

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