Consequences of preterm birth

By Michelle van Slobbe

As discussed in the introduction the relation between the female microbiome and pregnancy may lead to treatment to decrease the chance of preterm labour. But why? What exactly is preterm labour? And why is it important to prevent? By reading this blog you will find out the answers to these questions!

Epidemiology and mortality
Preterm birth is defined as babies being born before 37 weeks of gestation.[1] Preterm birth is very frequent, in more economically developed countries the percentage of children that is born preterm is approximately five to seven, and this percentage is even higher in less economically developed countries.[2] Apart from the fact that it occurs frequently, it also has consequences for the health of the children. To start with D’Onofrio et al.[3] showed in their research that the mortality is higher in preterm born children compared to children born at term (odds ratio see graph below).

Odds ratio of children born preterm compared to children born at term
From: https://jamanetwork.com/journals/jamapsychiatry/fullarticle/1743009
D’Onofrio BM, Class QA, Rickert ME, Larsson, Långström N, Lichtenstein P. Preterm birth and mortality and morbidity: A population based quasi-experimental study. JAMA psychiatry 2013; 70 (11): 10.

Morbidity
Not only do children born preterm have a higher chance of mortality, also the morbidity in these children is higher than in children born at term. Raju et al.[4] conducted a review of 126 publications to find out what the effects of preterm labour are on the general and system-specific health of children. They found that the majority of preterm born babies remain healthy during life, but the rest suffers from morbidities. In their study, they investigated the following organ system outcomes: brain structure, neurosensory, cognitive, mental health, psychiatric, cardiovascular, pulmonary, metabolic, and kidney.

Organ systems that can be affected as a result of preterm labour

Diagram self-made, pictures from: https://www.thedailybeast.com/is-psychiatry-being-stumped-by-the-mental-illnesses-it-has-to-treat, https://waitbutwhy.com/2017/04/neuralink.html, https://www.sporcle.com/games/timmylemoine1/heart-anatomy-pc, http://blogs.egusd.net/eettalfonso/2014/03/26/lungs-stage-1-of-respiration/, https://www.emaze.com/@AFRFWCTC, http://www.metroimmediatecare.com/kidney-top-10/

Starting with neurological outcomes, the researchers found that preterm birth can lead to reduced brain volume and that when a child has reduced cerebellar volume, this can lead to behavioural abnormalities. In addition to that, frequently studies show that children born preterm have a lower IQ and lower math abilities. The most significant psychiatric outcome that the authors found was that preterm-born children have a four times higher risk of anxiety and depression. The researchers also searched the 126 publications for cardiovascular outcomes and concluded that preterm-born individuals have a significantly higher blood pressure compared to individuals born at term. This higher blood pressure can lead to several health problems, for example, a heart attack, stroke or cardiac failure. In addition to these morbidities, the researchers also concluded that preterm-born children have a higher chance of pulmonary problems. Amongst others, these children have a higher risk of developing asthma and have a decreased percent forced expiratory volume by one second. Regarding the metabolic and kidney outcomes the researchers found that preterm birth is associated with a higher risk of developing diabetes mellitus type 2, but that more research was necessary to find out what the effects of preterm birth on kidney function are exactly.


We have just read that preterm birth is occurring frequently, that is related to a higher mortality and associated with many morbidities. We can conclude from this that it is important that methods are found to prevent preterm labour. The knowledge that has been gained in the next few years regarding the female microbiome may help us with finding this treatment. In this blog you can read more about this in innovative therapies.

This item of channel 4 news shows the consequences that preterm birth can have on the prematurely-born child. It also shows the strain that is put on a family when a child is prematurely before term.  

References consequenses of preterm birth[1] Institute of Medicine (US) Committee on Understanding Premature Birth and Assuring Healthy Outcomes; Behrman RE, Butler AS, editors. Preterm Birth: Causes, Consequences, and Prevention. Washington (DC): National Academies Press (US); 2007. 1, introduction.
[2] Beck S, Wojdyla D, Say L, Betran AP, Merialdi M, Harris Requejo J, Rubens C, Menon R, Van Look PFA. The worldwide incidence of preterm birth: a systematic review of maternal mortality and morbidity. Bulletin of the World Health Organization 2010;88:31-38.
[3]D’Onofrio BM, Class QA, Rickert ME, Larsson, Långström N, Lichtenstein P. Preterm birth and mortality and morbidity: A population based quasi-experimental study. JAMA psychiatry 2013; 70 (11): 10.
[4] Raju TNK, Buist AS, Blaisdell CJ, Moxey-Mims M, Saigal S. Adults born preterm: a review of general health and system-specific outcomes. Acta Paediatr. 2017;106(9):1409-1437.