Blood Sugar and the Developing Brain

22 Apr

A woman should be physically well and prepared before getting pregnant. Having either a low or high body mass index (BMI) is harmful to the developing fetus as both can lead to fetal undernutrition, among other else. Onset of this problem earlier than 20th weeks gestational age is already considered chronic episode, but the exact onset cannot be pin-pointed unless serial monitoring of the fetus development is done.

At birth, there are three anthropometric parameters that are important to be measured: the weight, length and the head circumference. These are then plotted against the baby’s age in weeks at the Lubchenco chart to determine if the baby’s measurement fall’s with accepted or normal range.



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The baby is then classified as small, appropriate or large for gestational age. Small for gestational age, SGA are those babies whose measurements (especially weight and head circumference) falls below the 10th %ile; large for gestational age, LGA, are those whose measurements fall above the 90th %ile; and appropriate for gestational age, AGA, are those whose measurements fall within the 10-90th %ile rank. Of the extremes, the SGAs are more common. There are various causes of SGA according to onset of the insult. Chronic onset usually happens when the insult started before the 20th gestational age, and this usually brings about a symmetric type where all measurement (weight, head circumference and length) fall below the 10 %ile line. Causes include chronic maternal hypertension and congenital infections with syphilis, toxoplasma, cytomegalovirus and rubella. If the insult occurred after the 20th gestational age, usually it is only the weight that gets affected bringing about an asymmetric type, but with sparing of the brain (hence it is also known as brain-sparing SGA). Such is what happens during cases of hypertensive disorders during the latter half of pregnancy. Common denominators of these would be a decrease in blood flow from the maternal circulation to the developing baby via the placenta-umbilical cord complex.

Maternal glucose influx into the fetus is very significant to the brain development. It should be understood that brain cells and red blood cells are the only body cells that do not require insulin to imbibe glucose from the circulating blood; they uptake glucose without help, and thus is dependent on the concentration of blood glucose. Normal level of blood glucose then should be maintained as adequate amount of glucose is an important determinant in the production of insulin-like growth factor (IGF), a significant factor in brain development. IGF is responsible in increasing the number of neurons and oligodendrocytes, as well as in increasing the arborization (connections) between axons and dendrites. (It has been established that the more arborizations between neurons, the faster the communication and thus the transmittal of information from one neuron to another, besides the effect of myelin sheath surrounding these structures). Inability therefore to sustain normal supply to brain cells for a long duration will significantly adversely affect the neuro-developmental outcome of the fetus, including his cognitive development. As even if the baby has inherited the genes to be genius but if this environmental factor in his development prevails, then it nullifies his potential of being genius at the end.


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If many mothers are nutritionally unprepared (whether because there’s too many children or there’s lack of adequate spacing between child births, among other else) before conceiving a child, would you then wonder why their children end up academically INADEQUATES in most cases? 

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A mother gave birth to a baby who was small for gestational age few days ago. Initially I was called in because the baby was reported as preterm, as based on ultrasound measurements. It turned out that the baby was near term at 36 weeks, but small for gestational age. I had the baby roomed-in with the mother after establishing that the baby seemed fine, except that I had to monitor the blood sugar. Initially the values were all normal so there was the plan to discharge the baby together with the mother. But on the day of supposed discharge, that’s when low blood sugar of the baby already occurred. Afraid of the risk of aggravating what might have already transpired already inside the uterus, I immediately had intravenous fluid administered to the baby. The grandmother was asking me what milk formula would be best to give so that this will not happen. I told her that oral feeding alone won’t resolve the problem, thus I stuck to breastfeeding still. With the help of iPad as visual aid (thanks to technology), I explained to the mother the consequences of low blood sugar to the developing brain. I emphasized that given the opportunity to correct possible adverse effect, as much as possible I didn’t baby to end up “bobo.”

IVF then helped normalize the blood sugar values. Every time I get a normal value, I try to decrease the rate at which the IVF was being infused, maintaining or increasing it back if the blood sugar dips below the accepted cut off value. Only at the seventh day of life did  the baby tolerate pure oral feedings and was thus given the clearance to go home.


Posted by on April 22, 2012 in neonates


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4 responses to “Blood Sugar and the Developing Brain

  1. christian

    January 18, 2014 at 8:58 am

    Thank you for such informative blog dok. Trying to reread everything right from the start, hope your okay now (saw the post regarding bypass).

    • drclintonb

      January 18, 2014 at 11:11 am

      thank you.
      yes, physically better now. my current task is to keep the cholesterol levels at bay or else, i will precipitate again blockade of the newly grafted vessels.

      • CJolou Dela Cruz

        February 4, 2014 at 6:46 am

        Seen you at the convention, looking good dok 🙂

      • drclintonb

        February 8, 2014 at 4:31 pm

        thank you. you should have approached me.


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