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What Is A Research (Scientific) Hypothesis? A plain-language explainer + examples

By:  Derek Jansen (MBA)  | Reviewed By: Dr Eunice Rautenbach | June 2020

If you’re new to the world of research, or it’s your first time writing a dissertation or thesis, you’re probably noticing that the words “research hypothesis” and “scientific hypothesis” are used quite a bit, and you’re wondering what they mean in a research context .

“Hypothesis” is one of those words that people use loosely, thinking they understand what it means. However, it has a very specific meaning within academic research. So, it’s important to understand the exact meaning before you start hypothesizing. 

Research Hypothesis 101

• What is a hypothesis ?
• What is a research hypothesis (scientific hypothesis)?
• Requirements for a research hypothesis
• Definition of a research hypothesis
• The null hypothesis

What is a hypothesis?

Let’s start with the general definition of a hypothesis (not a research hypothesis or scientific hypothesis), according to the Cambridge Dictionary:

Hypothesis: an idea or explanation for something that is based on known facts but has not yet been proved.

In other words, it’s a statement that provides an explanation for why or how something works, based on facts (or some reasonable assumptions), but that has not yet been specifically tested . For example, a hypothesis might look something like this:

Hypothesis: sleep impacts academic performance.

This statement predicts that academic performance will be influenced by the amount and/or quality of sleep a student engages in – sounds reasonable, right? It’s based on reasonable assumptions , underpinned by what we currently know about sleep and health (from the existing literature). So, loosely speaking, we could call it a hypothesis, at least by the dictionary definition.

But that’s not good enough…

Unfortunately, that’s not quite sophisticated enough to describe a research hypothesis (also sometimes called a scientific hypothesis), and it wouldn’t be acceptable in a dissertation, thesis or research paper . In the world of academic research, a statement needs a few more criteria to constitute a true research hypothesis .

What is a research hypothesis?

A research hypothesis (also called a scientific hypothesis) is a statement about the expected outcome of a study (for example, a dissertation or thesis). To constitute a quality hypothesis, the statement needs to have three attributes – specificity , clarity and testability .

Let’s take a look at these more closely.

Need a helping hand?

Hypothesis Essential #1: Specificity & Clarity

A good research hypothesis needs to be extremely clear and articulate about both what’ s being assessed (who or what variables are involved ) and the expected outcome (for example, a difference between groups, a relationship between variables, etc.).

Let’s stick with our sleepy students example and look at how this statement could be more specific and clear.

Hypothesis: Students who sleep at least 8 hours per night will, on average, achieve higher grades in standardised tests than students who sleep less than 8 hours a night.

As you can see, the statement is very specific as it identifies the variables involved (sleep hours and test grades), the parties involved (two groups of students), as well as the predicted relationship type (a positive relationship). There’s no ambiguity or uncertainty about who or what is involved in the statement, and the expected outcome is clear.

Contrast that to the original hypothesis we looked at – “Sleep impacts academic performance” – and you can see the difference. “Sleep” and “academic performance” are both comparatively vague , and there’s no indication of what the expected relationship direction is (more sleep or less sleep). As you can see, specificity and clarity are key.

Hypothesis Essential #2: Testability (Provability)

A statement must be testable to qualify as a research hypothesis. In other words, there needs to be a way to prove (or disprove) the statement. If it’s not testable, it’s not a hypothesis – simple as that.

For example, consider the hypothesis we mentioned earlier:

Hypothesis: Students who sleep at least 8 hours per night will, on average, achieve higher grades in standardised tests than students who sleep less than 8 hours a night.  

We could test this statement by undertaking a quantitative study involving two groups of students, one that gets 8 or more hours of sleep per night for a fixed period, and one that gets less. We could then compare the standardised test results for both groups to see if there’s a statistically significant difference. 

Again, if you compare this to the original hypothesis we looked at – “Sleep impacts academic performance” – you can see that it would be quite difficult to test that statement, primarily because it isn’t specific enough. How much sleep? By who? What type of academic performance?

So, remember the mantra – if you can’t test it, it’s not a hypothesis 🙂

Defining A Research Hypothesis

You’re still with us? Great! Let’s recap and pin down a clear definition of a hypothesis.

A research hypothesis (or scientific hypothesis) is a statement about an expected relationship between variables, or explanation of an occurrence, that is clear, specific and testable.

So, when you write up hypotheses for your dissertation or thesis, make sure that they meet all these criteria. If you do, you’ll not only have rock-solid hypotheses but you’ll also ensure a clear focus for your entire research project.

What about the null hypothesis?

You may have also heard the terms null hypothesis , alternative hypothesis, or H-zero thrown around. At a simple level, the null hypothesis is the counter-proposal to the original hypothesis.

For example, if the hypothesis predicts that there is a relationship between two variables (for example, sleep and academic performance), the null hypothesis would predict that there is no relationship between those variables.

At a more technical level, the null hypothesis proposes that no statistical significance exists in a set of given observations and that any differences are due to chance alone.

And there you have it – hypotheses in a nutshell. 

If you have any questions, be sure to leave a comment below and we’ll do our best to help you. If you need hands-on help developing and testing your hypotheses, consider our private coaching service , where we hold your hand through the research journey.

Psst... there’s more!

This post was based on one of our popular Research Bootcamps . If you're working on a research project, you'll definitely want to check this out ...

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16 Comments

Very useful information. I benefit more from getting more information in this regard.

Very great insight,educative and informative. Please give meet deep critics on many research data of public international Law like human rights, environment, natural resources, law of the sea etc

In a book I read a distinction is made between null, research, and alternative hypothesis. As far as I understand, alternative and research hypotheses are the same. Can you please elaborate? Best Afshin

This is a self explanatory, easy going site. I will recommend this to my friends and colleagues.

Very good definition. How can I cite your definition in my thesis? Thank you. Is nul hypothesis compulsory in a research?

It’s a counter-proposal to be proven as a rejection

Please what is the difference between alternate hypothesis and research hypothesis?

It is a very good explanation. However, it limits hypotheses to statistically tasteable ideas. What about for qualitative researches or other researches that involve quantitative data that don’t need statistical tests?

In qualitative research, one typically uses propositions, not hypotheses.

could you please elaborate it more

I’ve benefited greatly from these notes, thank you.

This is very helpful

well articulated ideas are presented here, thank you for being reliable sources of information

Excellent. Thanks for being clear and sound about the research methodology and hypothesis (quantitative research)

I have only a simple question regarding the null hypothesis. – Is the null hypothesis (Ho) known as the reversible hypothesis of the alternative hypothesis (H1? – How to test it in academic research?

this is very important note help me much more

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How to Develop a Good Research Hypothesis

The story of a research study begins by asking a question. Researchers all around the globe are asking curious questions and formulating research hypothesis. However, whether the research study provides an effective conclusion depends on how well one develops a good research hypothesis. Research hypothesis examples could help researchers get an idea as to how to write a good research hypothesis.

This blog will help you understand what is a research hypothesis, its characteristics and, how to formulate a research hypothesis

Table of Contents

What is Hypothesis?

Hypothesis is an assumption or an idea proposed for the sake of argument so that it can be tested. It is a precise, testable statement of what the researchers predict will be outcome of the study.  Hypothesis usually involves proposing a relationship between two variables: the independent variable (what the researchers change) and the dependent variable (what the research measures).

What is a Research Hypothesis?

Research hypothesis is a statement that introduces a research question and proposes an expected result. It is an integral part of the scientific method that forms the basis of scientific experiments. Therefore, you need to be careful and thorough when building your research hypothesis. A minor flaw in the construction of your hypothesis could have an adverse effect on your experiment. In research, there is a convention that the hypothesis is written in two forms, the null hypothesis, and the alternative hypothesis (called the experimental hypothesis when the method of investigation is an experiment).

Characteristics of a Good Research Hypothesis

As the hypothesis is specific, there is a testable prediction about what you expect to happen in a study. You may consider drawing hypothesis from previously published research based on the theory.

A good research hypothesis involves more effort than just a guess. In particular, your hypothesis may begin with a question that could be further explored through background research.

To help you formulate a promising research hypothesis, you should ask yourself the following questions:

• Is the language clear and focused?
• What is the relationship between your hypothesis and your research topic?
• Is your hypothesis testable? If yes, then how?
• What are the possible explanations that you might want to explore?
• Does your hypothesis include both an independent and dependent variable?
• Can you manipulate your variables without hampering the ethical standards?
• Does your research predict the relationship and outcome?
• Is your research simple and concise (avoids wordiness)?
• Is it clear with no ambiguity or assumptions about the readers’ knowledge
• Is your research observable and testable results?
• Is it relevant and specific to the research question or problem?

The questions listed above can be used as a checklist to make sure your hypothesis is based on a solid foundation. Furthermore, it can help you identify weaknesses in your hypothesis and revise it if necessary.

Source: Educational Hub

How to formulate a research hypothesis.

A testable hypothesis is not a simple statement. It is rather an intricate statement that needs to offer a clear introduction to a scientific experiment, its intentions, and the possible outcomes. However, there are some important things to consider when building a compelling hypothesis.

1. State the problem that you are trying to solve.

Make sure that the hypothesis clearly defines the topic and the focus of the experiment.

2. Try to write the hypothesis as an if-then statement.

Follow this template: If a specific action is taken, then a certain outcome is expected.

3. Define the variables

Independent variables are the ones that are manipulated, controlled, or changed. Independent variables are isolated from other factors of the study.

Dependent variables , as the name suggests are dependent on other factors of the study. They are influenced by the change in independent variable.

4. Scrutinize the hypothesis

Evaluate assumptions, predictions, and evidence rigorously to refine your understanding.

Types of Research Hypothesis

The types of research hypothesis are stated below:

1. Simple Hypothesis

It predicts the relationship between a single dependent variable and a single independent variable.

2. Complex Hypothesis

It predicts the relationship between two or more independent and dependent variables.

3. Directional Hypothesis

It specifies the expected direction to be followed to determine the relationship between variables and is derived from theory. Furthermore, it implies the researcher’s intellectual commitment to a particular outcome.

4. Non-directional Hypothesis

It does not predict the exact direction or nature of the relationship between the two variables. The non-directional hypothesis is used when there is no theory involved or when findings contradict previous research.

5. Associative and Causal Hypothesis

The associative hypothesis defines interdependency between variables. A change in one variable results in the change of the other variable. On the other hand, the causal hypothesis proposes an effect on the dependent due to manipulation of the independent variable.

6. Null Hypothesis

Null hypothesis states a negative statement to support the researcher’s findings that there is no relationship between two variables. There will be no changes in the dependent variable due the manipulation of the independent variable. Furthermore, it states results are due to chance and are not significant in terms of supporting the idea being investigated.

7. Alternative Hypothesis

It states that there is a relationship between the two variables of the study and that the results are significant to the research topic. An experimental hypothesis predicts what changes will take place in the dependent variable when the independent variable is manipulated. Also, it states that the results are not due to chance and that they are significant in terms of supporting the theory being investigated.

Research Hypothesis Examples of Independent and Dependent Variables

Research Hypothesis Example 1 The greater number of coal plants in a region (independent variable) increases water pollution (dependent variable). If you change the independent variable (building more coal factories), it will change the dependent variable (amount of water pollution).

Research Hypothesis Example 2 What is the effect of diet or regular soda (independent variable) on blood sugar levels (dependent variable)? If you change the independent variable (the type of soda you consume), it will change the dependent variable (blood sugar levels)

You should not ignore the importance of the above steps. The validity of your experiment and its results rely on a robust testable hypothesis. Developing a strong testable hypothesis has few advantages, it compels us to think intensely and specifically about the outcomes of a study. Consequently, it enables us to understand the implication of the question and the different variables involved in the study. Furthermore, it helps us to make precise predictions based on prior research. Hence, forming a hypothesis would be of great value to the research. Here are some good examples of testable hypotheses.

More importantly, you need to build a robust testable research hypothesis for your scientific experiments. A testable hypothesis is a hypothesis that can be proved or disproved as a result of experimentation.

Importance of a Testable Hypothesis

To devise and perform an experiment using scientific method, you need to make sure that your hypothesis is testable. To be considered testable, some essential criteria must be met:

• There must be a possibility to prove that the hypothesis is true.
• There must be a possibility to prove that the hypothesis is false.
• The results of the hypothesis must be reproducible.

Without these criteria, the hypothesis and the results will be vague. As a result, the experiment will not prove or disprove anything significant.

What are your experiences with building hypotheses for scientific experiments? What challenges did you face? How did you overcome these challenges? Please share your thoughts with us in the comments section.

Frequently Asked Questions

The steps to write a research hypothesis are: 1. Stating the problem: Ensure that the hypothesis defines the research problem 2. Writing a hypothesis as an 'if-then' statement: Include the action and the expected outcome of your study by following a ‘if-then’ structure. 3. Defining the variables: Define the variables as Dependent or Independent based on their dependency to other factors. 4. Scrutinizing the hypothesis: Identify the type of your hypothesis

Hypothesis testing is a statistical tool which is used to make inferences about a population data to draw conclusions for a particular hypothesis.

Hypothesis in statistics is a formal statement about the nature of a population within a structured framework of a statistical model. It is used to test an existing hypothesis by studying a population.

Research hypothesis is a statement that introduces a research question and proposes an expected result. It forms the basis of scientific experiments.

The different types of hypothesis in research are: • Null hypothesis: Null hypothesis is a negative statement to support the researcher’s findings that there is no relationship between two variables. • Alternate hypothesis: Alternate hypothesis predicts the relationship between the two variables of the study. • Directional hypothesis: Directional hypothesis specifies the expected direction to be followed to determine the relationship between variables. • Non-directional hypothesis: Non-directional hypothesis does not predict the exact direction or nature of the relationship between the two variables. • Simple hypothesis: Simple hypothesis predicts the relationship between a single dependent variable and a single independent variable. • Complex hypothesis: Complex hypothesis predicts the relationship between two or more independent and dependent variables. • Associative and casual hypothesis: Associative and casual hypothesis predicts the relationship between two or more independent and dependent variables. • Empirical hypothesis: Empirical hypothesis can be tested via experiments and observation. • Statistical hypothesis: A statistical hypothesis utilizes statistical models to draw conclusions about broader populations.

Wow! You really simplified your explanation that even dummies would find it easy to comprehend. Thank you so much.

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I enjoy reading the post. Hypotheses are actually an intrinsic part in a study. It bridges the research question and the methodology of the study.

Useful piece!

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It very interesting to read the topic, can you guide me any specific example of hypothesis process establish throw the Demand and supply of the specific product in market

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It is really a useful for me Kindly give some examples of hypothesis

It was a well explained content ,can you please give me an example with the null and alternative hypothesis illustrated

clear and concise. thanks.

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The Surprising Reason Behind the Evolution of Large Brains in Primates, According to New Research

T he intelligence of humans and other non-human primates is often attributed to our large brain sizes. The question of why some primate species developed large brains has intrigued scientists for years.

Many believe in the theory that a feedback loop is the explanation: clever animals find their nourishment more efficiently, acquire more calories, and thus sustain their larger brains. This hypothesis points to dietary preferences, particularly the amount of fruit consumed, and previous studies have connected brain size to this factor.

However, a recent study published in Proceedings of the Royal Society B has put this theory to the test directly for the first time.

Fruit-Eating Habits Observed in Panama

To test the “fruit-diet” hypothesis, researchers turned to the challenging task of quantifying foraging efficiency in wild animals. They capitalized on a natural experiment in Panama where various mammals are confined to consuming fruit from a few species during a periodic three-month timeframe, with focus on the Dipteryx oleifera tree.

Using drones to identify these trees from their distinctive purple flowers during flowering season, the researchers developed a comprehensive map that detailed the fruit landscape faced by the local wildlife.

The study included two large-brained primates, spider monkeys and white-faced capuchins, contrasted with two smaller-brained mammal species, white-nosed coatis and kinkajous. Observing over 40 individuals and analyzing over 600,000 GPS locations allowed them to measure the animals’ foraging efficiency.

Are Large-Brained Foragers More Efficient?

The expectation was that larger-brained primates would prove to have more efficient foraging patterns. Surprisingly, this was not supported by the findings – the route efficiency of primates was not significantly higher than that of their smaller-brained counterparts.

Alternative Explanations?

As the hypothesis connecting diet to brain size was not bolstered, the study turns attention to other possibilities, such as the importance of memory or the role of intelligence in tool use, which is observed in species with larger brains, like the white-faced capuchin monkey.

Moreover, the complexities of social interactions could be a significant factor in the evolution of large brains, an attribute found in various intelligent animals across the animal kingdom.

This research paves the way for future investigations into animal evolution, psychology, and behavior in a relatively undisturbed setting.

Ben Hirsch, Senior Lecturer in Zoology and Ecology at James Cook University, contributes this article republished from The Conversation under a Creative Commons license. View the original article .

FAQs About Primate Brain Evolution

What is the traditional hypothesis about primate brain evolution.

Traditionally, it has been thought that a feedback loop between intelligence and diet, particularly fruit consumption, led to the evolution of larger brains in primates. Smarter foraging strategies were believed to allow greater intake of calories, supporting a larger brain.

What did the new study in Panama find?

The study observed that large-brained primates like spider monkeys and white-faced capuchins did not forage more efficiently than smaller-brained animals like coatis and kinkajous, challenging the traditional diet-brain size hypothesis.

Why might primates have evolved large brains, according to this new study?

The study suggests alternative reasons such as the complexity of social interactions, memory advantages, or intelligence for tool use as potential drivers for the evolution of large brains in primates.

Did the study find any evidence to support the memory hypothesis?

Preliminary analyses did not support the hypothesis that better episodic memory in species with larger brains led to more optimized timing of fruit tree visits, but more in-depth research is needed to further evaluate this possibility.

What was unique about the methods used in this study?

This study utilized the latest sensor technologies and took advantage of a natural phenomenon to observe wild tropical mammals in their habitat, offering new insights into the evolution of animal intelligence and behavior in a non-invasive way.

Can the findings be applied to other intelligent species?

While this study specifically examined tropical mammals, the implications of the findings raise questions about the evolution of intelligence and brain size in other vertebrates and invertebrates, suggesting that similar studies could be beneficial in understanding these broader patterns.

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• Published: 31 May 2024

Pre-eclampsia and barker’s hypothesis: are we beginning to see the trees within the forest?

• Stephanie M. Tsoi 1 ,
• Martina Steurer 1 , 2 ,
• Emin Maltepe 1 &
• Jeffrey R. Fineman 1 , 3  

Pediatric Research ( 2024 ) Cite this article

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Dating back from Barker’s landmark reports beginning in 1986, abnormalities in the intrauterine environment have been suspected to influence the development of diseases later in life. Now referred to as Barker’s hypothesis, abnormalities in pregnancy have been associated with several childhood and adult diseases including systemic vascular, pulmonary vascular, and coronary artery diseases. The cellular and molecular explanations for Barker’s hypothesis have been postulated to be rooted in epigenetics and altered tissue differentiation throughout the life stages. 1 In the current issue of Pediatric Res , Kua et al.’s study provides novel insight into an early phenotype and unique biomarkers that may elucidate Barker’s hypothesis using the specific example of an abnormal intrauterine environment from pre-eclampsia (Pre-E) and its influence on the development of abnormal vascular reactivity.

Pre-E, a significant source of maternal and neonatal morbidities, occurs in up to 10% of pregnancies. Although the comprehensive etiology is not definitive, Pre-E is thought to, at least in part, be due to an abnormal development of the placental vasculature that results in a low flow, high resistance utero-placental unit. Immune dysregulation and inflammation are also important contributors. 2 This abnormal unit induces many aberrations that include a hypoxic-ischemic intrauterine environment and fetal growth restriction, along with the release of antiangiogenic, vasoconstricting, and inflammation promoting factors. These pathologies are then responsible for setting the stage for both offspring and maternal disorders. Offspring pathology spans multiple systems - CNS, respiratory, gastrointestinal, renal, immunologic, and cardiovascular (including vascular endothelial dysfunction and subsequent vascular disease). Maternal pathology, often referred to as maternal-placental syndromes, includes an increased risk of cardiovascular disease. 3

The thoughtfully designed study by Kua et al. utilizes non-invasive tools to compare both vascular structure and function in 6-month-old healthy controls and infants born to mothers with Pre-E. In addition, blood was sampled to compare 17 serum biomarkers between the groups. They found no difference in systemic blood pressure or microvessel density, but there was a difference in vascular reactivity in their adjusted model. Kua et al. also showed an increase in two cytokines – IL-8 (a pro-inflammatory marker) and Angiopoeitin-2 (a growth factor involved in angiogenesis and vascular remodeling) in infants born to Pre E mothers. Most interesting was that they found a negative association between IL-8 and vascular reactivity. Kua et al. expertly demonstrated that the childhood and adult-onset vascular diseases associated with Pre-E likely emerge during infancy.

Kua et al.’s findings are novel and add to our limited understanding of the complex interplay between abnormal placentas, fetal inflammation, and post-birth outcomes. Kua et al. has elegantly chosen outcomes that measure both the structure, development, and function of the highly susceptible vasculature. However, some limitations and inconsistencies with previous studies are noteworthy. For example, in the current study non-invasive systemic blood pressure was not different between the groups. This contradicts a previous investigation that demonstrated increases in systolic, diastolic, and mean systemic blood pressures in the offspring of Pre-E mothers from day 2 to 4 weeks of life. 4 In this study, Chourdakis et al. only investigated offspring from early onset Pre-E (<34 weeks gestation). This distribution of early vs. late onset Pre-E is not documented by Kua et al., but separate analysis was likely not possible given the sample size limitations of the current study. Like many pathologies, pregnancies associated with Pre-E have similarities as well as differences that would be important to delineate when attempting to discern mechanisms of disease. From the contradictory results with blood pressure, it appears that the timing of Pre-E during gestation is critical. In fact, differences in several growth factors have been documented between early and late onset Pre-E. 5 Additionally, larger cohort studies could control for several vital maternal and pregnancy factors including severity of Pre-E, antenatal steroid use, maternal BMI, and mode of conception. For example, in-vitro fertilization (IVF) is associated with a high incidence of Pre-E, placental pathology, pre-term delivery, and childhood and adult-onset vascular disease which may have overlapping, as well as independent, pathologic mechanisms. 6 In fact, differences in these variables, including IVF use across groups, may have confounded the findings in the current study. Importantly, it is unfortunate that gestational age at birth could not be adequately matched between the groups (Kua et al. Table 1, >1 week gestation older in controls). Although adjusted for in their models, gestational length is such a strong confounder that direct matching would be ideal and facilitate the ability to better adjust for other variables. Finally, the lack of correlation with placental pathology is a lost opportunity to leverage the placenta to advance neonatal care. 7 The presence and degree of maternal vascular malperfusion and/or histologic evidence of inflammation, for example, can be highly informative with respect to underlying etiology as well as long term disease susceptibility. 8

Kua et al. should be applauded for not only assessing both vascular structure and function, but doing so in a non-invasive manner that facilitated study enrollment in a vulnerable patient age group. This allowed studies at an age interval (6 months) that had not been previously investigated. However, with these non-invasive assessments come inherent shortcomings. For example, as the authors nicely discuss, the functional assessment of vascular structure utilizing microvascular density could be improved with newer dark field microscopy and the addition of re-perfusion measurements. In addition, the assessment of vascular reactivity was performed utilizing acetylcholine (Ach) dose responses. Ach is a classic endothelium-dependent vasodilator that facilitates nitric oxide (NO) release following Ach receptor binding. More commonly, and more uncomfortable, flow mediated vasodilation is utilized, which also assesses NO-induced vasodilation using the physiologic flow (shear stress) stimulus, bypassing the need for any receptor binding. Although blunted Ach responses almost certainly reflect impaired NO release secondary to endothelial dysfunction, potential aberrations in Ach receptor density and/or affinity cannot be excluded. In addition, often the assessment of endothelium-independent vasodilation is also tested with NO-donors, such as nitroprusside, that can assess aberrations in vasodilation beyond endothelial function. Although the addition of these assessments would add value, the approach that Kua et al. undertook is completely understandable given the young patient population. However, we cannot lose site of the fact that the diagnostic and prognostic value of these methodologies requires further investigation.

To begin to explore the potential inflammatory-induced changes, Kua et al. performed a venipuncture to determine and compare cytokine profiles. Importantly, their assessment discovered both similarities and differences in cytokine profiles. In a secondary analysis they also demonstrate an inverse relationship between IL-8 levels and vascular reactivity. This fascinating data may shed light on not only a potential biomarker of future disease, but also provide insight into potentials mechanisms of pathology, since IL-8 has been implicated in both endothelial and smooth muscle cell proliferation. 9 In fact, continued assessment of these profiles with increasing age could provide important mechanistic insights.

We thank Kua et al. for contributing these valuable results to our greater understanding of the long-lasting impact of the intrauterine environment on the outcomes of offspring. This area of research will greatly benefit from further scientific inquiry, and we hope that this study’s findings will prompt future research that aims to better understand Barker’s hypothesis on a cellular, molecular, and biochemical level. This includes the need for large-scale multi-institutional prospective studies that involves careful pathologic examination of the placenta, maternal, umbilical, and sequential postnatal blood sampling, and sequential assessments of cardiovascular structure and function. Only then will we begin to see the trees within the forest of the Barker hypothesis, that could lead to important mechanistic insight facilitating novel treatment and prevention strategy discovery.

Barker, D. J. The fetal and infant origins of adult disease. BMJ 301 , 1111 (1990).

Article   CAS   PubMed   PubMed Central   Google Scholar  

Deer, E. et al. The role of immune cells and mediators in preeclampsia. Nat. Rev. Nephrol. 19 , 257–270 (2023).

Ray, J. G., Vermeulen, M. J., Schull, M. J. & Redelmeier, D. A. Cardiovascular health after maternal placental syndromes (CHAMPS): population-based retrospective cohort study. Lancet 366 , 1797–1803 (2005).

Article   PubMed   Google Scholar  

Chourdakis, E. et al. Effect of early-onset preeclampsia on offspring’s blood pressure during the first month of life. J. Pediatr. 220 , 21–26.e1 (2020).

Raymond, D. & Peterson, E. A critical review of early-onset and late-onset preeclampsia. Obstet. Gynecol. Surv. 66 , 497–506 (2011).

Ganer Herman, H. et al. Obstetric and perinatal outcomes of in vitro fertilization and natural pregnancies in the same mother. Fertil. Steril. 115 , 940–946 (2021).

Mestan, K. K. et al. Leveraging the placenta to advance neonatal care. Front Pediatr. [Internet] . May [cited 2024 Apr 1]; 11 . Available from: https://doi.org/10.3389/fped.2023.1174174 (2023).

Redline, R. W. et al. Placental pathology is necessary to understand common pregnancy complications and achieve an improved taxonomy of obstetrical disease. Am. J. Obstet. Gynecol. 228 , 187–202 (2023).

Wang, Y. et al. Induction of interleukin-8 gene expression and protein secretion by C-reactive protein in ARPE-19 cells. Exp. Eye Res. 91 , 135–142 (2010).

Article   CAS   PubMed   Google Scholar  

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Supported by the National Institutes of Health (T32HL160508-01A1 [SMT], P01 HL146369 [JRF]).

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Stephanie M. Tsoi, Martina Steurer, Emin Maltepe & Jeffrey R. Fineman

Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA, USA

Martina Steurer

Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA

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Tsoi, S.M., Steurer, M., Maltepe, E. et al. Pre-eclampsia and barker’s hypothesis: are we beginning to see the trees within the forest?. Pediatr Res (2024). https://doi.org/10.1038/s41390-024-03264-7

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Rethinking the sun's cycles: New physical model reinforces planetary hypothesis

by Simon Schmitt, Helmholtz Association of German Research Centres

Researchers at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the University of Latvia have posited the first comprehensive physical explanation for the sun's various activity cycles. It identifies vortex-shaped currents on the sun, known as Rossby waves, as mediators between the tidal influences of Venus, Earth as well as Jupiter and the sun's magnetic activity.

The researchers therefore present a consistent model for solar cycles of different lengths—and another strong argument to support the previously controversial planetary hypothesis. The results have now been published in the journal Solar Physics .

Although the sun, being near to us, is the best researched star, many questions about its physics have not yet been completely answered. These include the rhythmic fluctuations in solar activity . The most famous of these is that, on average, the sun reaches a radiation maximum every eleven years—which experts refer to as the Schwabe cycle.

This cycle of activity occurs because the sun's magnetic field changes during this period and eventually reverses polarity. This, in itself, is not unusual for a star—if it weren't for the fact that the Schwabe cycle is remarkably stable.

The Schwabe cycle is overlaid by other, less obvious fluctuations in activity ranging from a few hundred days to several hundred years, each named after their discoverers. Although there have already been various attempts to explain these cycles and mathematical calculations, there is still no comprehensive physical model.

Planets set the beat

For some years, Dr. Frank Stefani of HZDR's Institute of Fluid Dynamics has been an advocate of the "planetary hypothesis" because it is clear that the planets' gravity exerts a tidal effect on the sun, similar to that of the moon on the Earth. This effect is strongest every 11.07 years: whenever the three planets Venus, Earth and Jupiter are aligned with the sun in a particularly striking line, comparable to a spring tide on Earth when there is a new or full moon. This coincides conspicuously with the Schwabe cycle.

The sun's magnetic field is formed by complex movements of the electrically conducting plasma inside the sun. "You can think of it like a gigantic dynamo. While this solar dynamo generates an approximately 11-year activity cycle in its own right, we think the planets' influence then intervenes in the workings of this dynamo, repeatedly giving it a little push and thus forcing the unusually stable 11.07-year rhythm on the sun," Stefani explains.

Several years ago, he and his colleagues discovered strong evidence of a clocked process of this kind in the available observation data. They were also able to correlate various solar cycles with the movement of the planets just using mathematical methods. At first, however, the correlation could not be sufficiently explained physically.

Rossby waves on the sun act as intermediaries

"We have now found the underlying physical mechanism. We know how much energy is required to synchronize the dynamo, and we know that this energy can be transferred to the sun by so-called Rossby waves. The great thing is that we can now not only explain the Schwabe cycle and longer solar cycles but also the shorter Rieger cycles that we hadn't even considered previously," says Stefani.

Rossby waves are vortex-shaped currents on the sun similar to the large-scale wave movements in the Earth's atmosphere that control high- and low-pressure systems.

The researchers calculated that the tidal forces during the spring tides of two of each of the three planets Venus, Earth and Jupiter had exactly the right properties to activate Rossby waves—an insight with many consequences.

First of all, these Rossby waves then achieve sufficiently high speeds to give the solar dynamo the necessary impetus. Second, this occurs every 118, 193 and 299 days in accordance with the Rieger cycles that have been observed on the sun. And thirdly, all additional solar cycles can be calculated on this basis.

All cycles explained by a single model

This is where mathematics comes in: The superimposition of the three short Rieger cycles automatically produces the prominent 11.07-year Schwabe cycle. And the model even predicts long-term fluctuations of the sun because the movement of the sun around the solar system's center of gravity causes a so-called beat period of 193 years on the basis of the Schwabe cycle.

This corresponds to the order of magnitude of another cycle that has been observed, the Suess-de Vries cycle.

In this context, the researchers discovered an impressive correlation between the 193-year period that had been calculated and periodic fluctuations in climate data. This is another robust argument for the planetary hypothesis because "the sharp Suess-de Vries peak at 193 years can hardly be explained without phase stability in the Schwabe cycle, which is only present in a clocked process," Stefani estimates.

Does this mean the question as to whether the sun follows the planets' beat has finally been answered? Stefani says, "We'll probably only be 100% certain when we have more data. But the arguments in favor of a process clocked by the planets are now very strong."

Journal information: Solar Physics

Provided by Helmholtz Association of German Research Centres

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