Low Birth Weight & Kidney Disease

Were you born prematurely before completing “9 months of nurturing” in your mum’s womb? Or did you have a Low Birth Weight despite being a “Term baby”?

Low Birth Weight baby
Image credit: Wikimedia Commons

In that case, you may want to consider getting a medical opinion about your chances of developing high blood pressure, cardiovascular (heart) disease and kidney disease later in life.

Wonder why?

Read on to understand.



Normally, all babies completing a full gestation period of 37-40 weeks in their mother’s womb in good health weigh between 2.5 kilograms (5.5 pounds) to 4 kilograms (approximately 8 pounds). The World Health Organization (WHO) defines “Low Birth Weight” as weighing less than 2500 grams / 2.5 kilos or in other words, 5.5 pounds at birth. It is a significant health problem on a global scale. Overall, 15-20% of all births worldwide annually or on a more absolute note, about 20 million births every year, belong to this subset on a global scale.

Low Birth Weight could be a result of a child being born too early, before completing the required 37 weeks of womb development (Pre-term baby). Alternatively, it could result from the baby in the womb not growing at the expected pace either because of a health-complication affecting the mother or the baby itself (Intra-uterine growth restriction).

Irrespective of the cause, birth-weight below 2.5 kilograms comes with its own set of both short-term & long-term consequences. Kidney disease in later life is one such possibility for such babies.

So why is Low Birth Weight a “risk factor” for Kidney Disease in later life?


Is there anything you can do about it?


That is what this article focuses on.



While developing in the womb, our kidneys assume their final shape & function by a process called “Branching Morpho-genesis”. This mouthful term simply means that the nephrons or filtration units in the kidney expand in number by a series of branching episodes. This is somewhat like what we see in a tree. The illustration below explains how this works.

Low Birth Weight Branching Morphogenesis Kidney

It takes a full 37 weeks to complete all the branching episodes necessary to render the normal number of nephrons (900,000 to 1.5 million per kidney) to ensure our kidneys function seamlessly after birth.

Low Birth Weight babies (less than 2500 grams), especially the ones born pre-term i.e. before completing 37 weeks of womb development are unable to complete all requisite branching episodes. As a result, each kidney falls short of attaining the normal nephron number.

Alternatively, babies showing poor growth in their mother’s womb can have a low birth weight despite completing 37 weeks. In such babies, the kidneys would still present with a low nephron number like their premature counterparts. However, instead of “incomplete” kidney development as in pre-terms, this concerns with “factors that prevent / restrict” adequate kidney branching.




Inadequate nephron numbers render kidneys relatively weak than those in normal birth weight babies. Weaker kidneys due to an abnormally low nephron number severely impact kidney functionality. 

Low Birth Weight

Among other things, it effectively dampens the ability of our Kidneys to regulate our blood pressure. Hence, humans weighing below 2.5 kilograms at birth are considered “at-risk” of developing High Blood Pressure over time.


In Humans, Blood Pressure is chiefly controlled by 3 mechanisms. These are the Heart, the Kidney & by some Hormones.

Whatever be the initiator, Uncontrolled, untreated high blood pressure sustained over a few years ends-up damaging kidneys in the long run. It is one of the most important preventable causes of Kidney Disease in later life.


Low birth weight initially raises blood pressure by compromising the Kidney’s BP regulation machinery. Later on, additional factors join-in to cause full-blown kidney damage if the initial rise in blood pressure remains untreated.


Briefly speaking, kidney damage in Low Birth Weight individuals sets-in as follows:

Low Birth Weight bell Kidneys encounter the entire quantum of 5L of blood in our body for 40 times daily to carry out its job of blood filtration. Each time, this blood gets equally distributed to each of the tiny nephrons (kidney filters). This Division of Labour & allows for a seamless rendering of the job 24 X 7.

Besides, the kidney cells themselves need a good 20% of all the blood pumped by our heart for their own survival & sustenance.

Low Birth Weight bell Long-term, untreated high blood pressure literally “assaults & injures” our delicate kidney filters every time it “gets in touch”. Add to that a low nephron count at birth and it means each nephron having to bear a greater load of blood “angrily gushing towards it at high pressure”, than otherwise. All this paves the way for initiation of kidney disease in patients with a Low Birth Weight.

Low Birth Weight bell Further, uncontrolled high BP sustained over a few years is enough to damage blood vessel walls irreversibly, such that they stiffen-up permanently. This, in turn, prevents blood vessels from widening or narrowing as per need and interferes with proper blood supply to other body organs.

As a result, the heart needs to pump “with greater force” during each beat to attempt adequate blood supply to other organs. This only worsens our body’s overall ability to regulate blood pressure.

Low Birth Weight bell With time, blood vessels progressively “harden their stance” against the “rowdiness” of the blood constantly flowing at a high pressure. Ultimately, this cuts back on the overall blood flow to the already injured kidney. Since blood also happens to “ferry” life-saving Oxygen to all organs, poor blood flow to kidney means it gets deprived of adequate Oxygen Supply as well.


So, in a nutshell, here’s summarizing the reasons for kidney damage in later life in Low Birth Weight individuals:

! Low Birth Weight A constant assault of high-pressure blood on delicate nephrons (kidney filters)

! Low Birth Weight Less than normal nephron count to handle the load of this “bloody stress”

! Low Birth Weight Progressive reduction of blood flow to kidneys over time


! Low Birth Weight Poor delivery of life-sustaining oxygen to the kidney tissue. 


Hence, Low Birth Weight features as a prominent Risk Factor for Chronic Kidney Disease (CKD) in later life. And once such kidney disease sets-in, the damage is usually irreversible. Such kidney disease progresses to chart the full course all the way up to Kidney Failure in 5-10 years time unless otherwise diagnosed in good time.




Just because something is a Risk Factor for kidney disease does not mean it will necessarily progress to cause full-blown kidney disease.

Also, since the whole mechanism of kidney damage in Low Birth Weight (less than 2.5 kg) proceeds via High Blood Pressure, it is also a PREVENTABLE cause of Kidney Disease.




Low Birth Weight Tick Try getting an idea about your body weight & general health at birth.

If you are aware of your birth weight, fantastic! If not (quite possible), consider learning about what increases a pregnant woman’s chances of delivering a low birth weight baby. This can help you assess your chances of having weighed less than 2.5 kg / 5 pounds at birth.

Low Birth Weight Tick If you do happen to be a Low Birth Weight individual, consider seeking a medical opinion on whether you are at-risk.

Low Birth Weight Tick Get a simple blood pressure monitoring done by your doctor. If it is normal, great! If it is high, your doc may prescribe you a medicine to lower your BP & advise you certain lifestyle changes. Please stick to those religiously.

Low Birth Weight Tick Try to retain a healthy body weight commensurate with your height and age. Obesity or even being underweight can complicate things. Optimize Meal Portions & Pick an activity of your choice to meet your daily fitness goals.

Low Birth Weight Tick Lower (Sodium) salt intake. Sodium is a naturally occurring mineral found in our blood. It plays a major role in preventing our blood pressure from falling below normal.

Table salt & condiment sauces are the commonest food items that can allow excess sodium to creep into our systems.

In normal health, kidneys flush out this excess sodium from the system — a capability that takes a hit with less nephron count. As a result, it raises our blood pressure beyond normal limits.

Simply cutting down on adding extra table salt and maybe some that mayonnaise can help you go a long way in preventing the onset of kidney damage! And it’s not half as bad as it sounds. Especially because you can go for low-sodium seasoning alternatives and still make your food taste equally yummy! Learn how you can do so, here. Learn how you can do so, here.

Low Birth Weight Tick Stay hydrated! Drink at least 2 to 2.5 litres water daily.

Low Birth Weight TickAdopt stress-management techniques & try to clock at least 7 hrs of sleep at night. 

Salt free seasonings / condiments for a Low Sodium diet


So you see, preventing Kidney Disease specifically because of your Low Birth Weight is that simple. It’s all about being aware, knowing your health status & making a few adjustments to your lifestyle.

However, please note, if you have other conditions that could affect your kidneys such as Diabetes, Kidney Stones, Inflammation of your kidneys or Kidney structure abnormalities, you will need to be treated for those separately. The disease course and your response to treatment would vary individually.



This article intends to instil the age-old proverb into practice – “Prevention is better than cure”. This is the precise benefit of learning about Risk Factors of a certain disease state. If you are indeed a Low Birth Weight adult leading a reasonably healthy life, please try not to get demoralized by this post. That is absolutely not the purpose. Rather, it is to help you continue living a healthy life, free of any interruptions from any preventable health-issue.

Talk to your doctor to get assessed at the earliest. Time is always a precious commodity in all things health, so the sooner, the better.

Stay informed, stay well.




Then please do not hesitate to share it (by clicking on the Share-Buttons below) with your social circle. Spread this piece of information as much as you can and contribute your two cents towards empowering the Kidney Community!



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