Does Vitamin D Affect IQ?

The Importance Of Vitamin D During Pregnancy

Author: Dr. Stephen Chaney

pregnant women taking vitaminAs an expectant mother, you want the best for your child. You want them to be healthy and happy. You probably also want them to be smart.

Your doctor has recommended you take a prenatal supplement. You have probably heard about the importance of folic acid for a successful pregnancy. I have also written about the importance of adequate omega-3s and iodine during pregnancy for the cognitive development of your child.

But what about vitamin D? Vitamin D receptors are expressed in the mammalian brain as early as 12 days into gestation, and vitamin D is thought to be important in neurocognitive development.

Previous studies have shown that vitamin D deficiency during pregnancy is associated with delayed motor-skill and social development during the first few years of childhood. But it is uncertain whether these early deficits translate into long-term deficits in IQ and emotional stability.

This study was designed to answer that question by comparing blood 25-hydroxyvitamin D levels in the mother’s blood during the second trimester and IQ measurements of their children between the ages of 4 and 6.

How Was This Study Done?

Clinical StudyThis study used data from the CANDLE (Conditions Affecting Neurocognitive Development and Learning in Early Childhood) database. This portion of the study measured blood levels of 25-hydroxyvitamin D during the second trimester of pregnancy of 1503 women from the Memphis area of Tennessee. The 25-hydroxyvitamin D levels were compared with the IQ of their children measured between the ages of 4 and 6.

The average age of the mothers was 26 and 63% of them were black.

Of course, there are many other factors that influence mental development during childhood. Accordingly, the data were corrected for the overall quality of the maternal diet, maternal IQ, maternal education, maternal age, marital status, BMI (a measure of obesity), tobacco use during pregnancy, alcohol use during pregnancy, and household income.

Does Vitamin D Affect IQ?

child geniusHere are the results from the study:

  • The average blood level of 25-hydroxyvitamin D at week 23 of pregnancy was 21.6 ng/mL.
    • 45.6% of the women were vitamin D deficient (<20 ng/mL 25-hydroxyvitamin D).
  • The average blood level of 25-hydroxyvitamin D in this study was 19.8 ng/mL for Black women and 25.9 ng/mL for White women.
    • This is consistent with a previous report that 80% of Black pregnant women in this country are vitamin D deficient compared to only 13% of White pregnant women.
  • After adjusting for other variables known to affect IQ, every 10ng/mL increase in 25-hydroxyvitamin D status during pregnancy resulted in an increase of:
    • 1.17 points in overall IQ.
    • 1.17 points in verbal IQ.
    • 1.03 points in nonverbal IQ.
  • The effect of vitamin D status during pregnancy on IQ of the offspring at ages 4-6 was the same for both races.
  • The effect of maternal vitamin D status on childhood IQ plateaued at around 40ng/mL, which is near the top of what is considered an adequate level of 25-hydroxyvitamin D.

The authors of the study concluded: “Gestational vitamin D concentrations were positively associated with IQ at age 4-6, suggesting that vitamin D plays an important role in programming neurocognitive development. Vitamin D status may be an important modifiable factor that can be optimized through appropriate nutritional recommendations and guidance. Vitamin D deficiency was especially prevalent among Black women in this cohort, suggesting a higher need for screening and nutritional intervention in this vulnerable population.”

The authors went on to say: “Vitamin D supplementation may be indicated for women who have poor dietary intake of vitamin D and/or reduced cutaneous synthesis related to skin pigmentation [Simply put, sunlight can catalyze the synthesis of vitamin D in our skin, but skin pigmentation filters out the sunlight and decreases vitamin D synthesis.]…”

The Importance Of Vitamin D During Pregnancy

vitamin dLet me put this study in perspective by first discussing the pros and cons of the study. Then I will close with what I think is the most important takeaway from the study.

The Cons Of The Study:

The cons are obvious:

  1. This study shows that a 10 ng/mL increase in 25-hydroxyvitamin D during pregnancy is associated with about a 1-point increase in IQ on a 100-point scale? Is that significant? Probably not, especially when you consider all the other dietary and environmental factors that influence intelligence and educational attainment.

2) We don’t know whether this effect of vitamin D status during pregnancy on IQ will persist as the children grow up. It is more likely that socioeconomic and family factors during childhood will play a much larger role in educational attainment.

The Pros Of The Study:

  1. This study is superior to most previous studies on this topic because of its size and duration. It is also a well-designed study.

2) The authors pointed out a previous study has reported that for each decrease of one IQ point:

    • Lifetime income for men decreases by 1.93%.
    • Lifetime income for women decreases by 3.23%.

3) The effect of vitamin D status during pregnancy on IQ at age 4-6 plateaued at 40 ng/mL. That means the women in this study would obtain optimal benefit by increasing their 25-hydroxyvitamin D levels by 20 ng/mL. Since each 10 ng/mL increase in 25-hydroxyvitamin D during pregnancy increased IQ by 1.17, this would translate into:

  • A 4.5% increase in lifetime earnings for men.
  • A 7.6% increase in lifetime earnings for women.
  • When you look at it this way, the effect of vitamin D during pregnancy on IQ seems a bit more significant.

The Most Important Takeaway From This Study:

  • Of all the things you can do during pregnancy to give your kids an advantage in today’s competitive world, supplementation with vitamin D before and during pregnancy is probably the simplest, cheapest, and safest option available to you.
  • Even if optimizing 25-hydroxyvitamin D levels during pregnancy has no long-term effect on your child’s IQ, we know it has many other benefits for your health and your child’s health.
  • And, as long as you don’t exceed 50 ng/mL of 25-hydroxyvitamin D, it is perfectly safe.

The authors had this to say about supplementation with vitamin D before and during pregnancy: “Popular prenatal supplements, which typically contain 400-600 IU vitamin D, are likely insufficient to correct 25-hydroxyvitamin D deficiencies. Randomized controlled trials have suggested that daily supplementation of 800 to 1,000 may be needed during pregnancy, and that doses of 4,000 IU may be ideal in cases of severe deficiency.”

The Bottom Line

A recent study looked at 25-hydroxyvitamin D status during the second trimester of pregnancy and the IQ of the offspring at ages 4-6. The study found:

  • The average blood level of 25-hydroxyvitamin D at week 23 of pregnancy was 21.6 ng/mL.
    • 6% of the women were vitamin D deficient (<20 ng/mL 25-hydroxyvitamin D).
    • After adjusting for other variables known to affect IQ, every 10ng/mL increase in 25-hydroxyvitamin D status during pregnancy resulted in an increase of 1.17 points in overall IQ.
  • The effect of maternal vitamin D status on childhood IQ plateaued at around 40ng/mL, which is near the top of what is considered an adequate level of 25-hydroxyvitamin D.

The authors of the study concluded: “Gestational vitamin D concentrations were positively associated with IQ at age 4-6, suggesting that vitamin D plays an important role in programming neurocognitive development. Vitamin D status may be an important modifiable factor that can be optimized through appropriate nutritional recommendations and guidance…”

The authors went on to say: “Vitamin D supplementation may be indicated for women who have poor dietary intake of vitamin D and/or reduced cutaneous synthesis related to skin pigmentation…”

In terms of supplementation, the authors said: “Popular prenatal supplements, which typically contain 400-600 IU vitamin D, are likely insufficient to correct 25-hydroxyvitamin D deficiencies. Randomized controlled trials have suggested that daily supplementation of 800 to 1,000 may be needed during pregnancy, and that doses of 4,000 IU may be ideal in cases of severe deficiency.”

For more details and my perspective of the study, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

Could Mom’s Stress Affect Her Baby’s Health?

How Can You Minimize Stress During Pregnancy?

StressIf you are pregnant, the advice you see on the internet can be overwhelming. There are so many things you “must do” and so many things you “must avoid” if you want a healthy baby. It’s enough to stress you out.

As if that weren’t bad enough, we are probably living through the most stressful period in recent memory. So, the last thing you want to hear is that your stress during pregnancy can affect the health of your baby.

Before I go any further, let me make it clear that the studies I will discuss in this issue of “Health Tips From the Professor” are intriguing, but they are preliminary. I don’t want to add to your stress.

Let me start by reviewing the literature:

  • Several studies suggest that stress during pregnancy is associated with preterm birth, low birthweight, and infant mortality.
  • Other studies suggest that stress during pregnancy is associated with suboptimal cognitive development, hyperactivity, and asthma in the offspring.

The big question, of course, is how a mom’s stress during pregnancy can affect the health of her child months or years later. One hypothesis is that stress affects the mom’s gut bacteria, and those gut bacteria are passed along to the child as he or she passes through the birth canal.

We know that stress can affect your gut bacteria, but can it affect your child’s gut bacteria? Studies in mice suggest it can. Today I will discuss the first large clinical study (AK Aatsinki et al, Pyschoneuroendocrinology, 119 (2020) 104754) designed to evaluate that hypothesis in humans.

How Was This Study Done?

Clinical StudyThis study was an offshoot of an ongoing FinnBrain Cohort Project, which aims to study the influence of stress exposures during pregnancy on later childhood development and health outcomes. This particular study was designed to investigate the role of chronic stress during pregnancy on the population of gut bacteria in infants. There were 399 mothers and their babies who completed this study.

All Participants in the FinnBrain Project:

  • Filled out self-reported prenatal questionnaires at gestational weeks 14, 24, and 34. These questionnaires provided background information about the health, weight, age, and education level of the moms, as well as whether they were taking antidepression medications during their pregnancy.
  • Were also asked about breast feeding 2.5 months after giving birth.
  • Duration of gestation, birth weight, and method of delivery information were obtained from Finland’s National Institute for Health and Welfare.

Participants in this study:

  • Were evaluated for depression and anxiety symptoms three times during pregnancy and at 3 months after giving birth. It should be noted that the questionnaires used to evaluate depression and anxiety symptoms did not measure the stressors (events causing the stress). Instead they were measuring the mom’s response to those stressors.
  • Cortisol levels were measured at gestational week 24 as another measure of the mother’s stress level.
  • Fecal samples were obtained from the offspring at the age of 2.5 months and analyzed for the population of gut bacteria.

Could Mom’s Stress Affect Her Baby’s Health?

Bad BacteriaThe results of this study were intriguing:

Infants born to mothers who experienced high levels of stress (such as depression and/or anxiety) during pregnancy had an increased abundance of potentially pathogenic gut bacteria such as:

  • Serratia, Haemophilus, Citrobacter, and Campylobacter from the Proteobacteria group of bacteria.
  • Veillonella and Finegoldia from the Firmicutes group of bacteria.

In addition, infants born to mothers with elevated cortisol levels (another measure of stress) had decreased abundance of potentially health promoting gut bacteria such as Lactobacillus.

In contrast:

  • Infants born to mothers who experienced low levels of stress had increased levels of potentially health promoting gut bacteria, such as Akkermansia.
  • Infants born to mothers with low cortisol levels had an increased abundance of Lactobacillus in their gut.

In short:

  • High levels of stress in the mother during pregnancy are associated with an increased abundance of unhealthy bacteria in their baby’s intestine.
  • Low levels of stress in the mother during pregnancy are associated with an increased abundance of healthy bacteria in their baby’s intestine.

The authors concluded:

“The observed fecal bacteria signature in the infants with exposure to chronic maternal stress, such as increased abundance of potentially inflammatory bacteria from the Proteobacteria group of bacteria, warrant future follow-up of these children, since similar alterations of fecal bacteria have previously been associated with adverse health outcomes such as asthma in children.

The results of this study describe only associations, yet corroborate certain interesting findings reported in earlier literature and offer hypotheses for future mechanistic studies.”

How Can You Minimize Stress During Pregnancy?

Simply put, this study shows that chronic stress during pregnancy increases populations of gut bacteria in the newborn that are associated with adverse health outcomes in children. More studies are needed to confirm and understand this observation, but it raises an issue that is often ignored.

Pregnancy can be a stressful time, especially if you are a first-time mom. Plus, we are living in the most stressful time any of us can remember. So, this study is particularly relevant today.

However, let’s put this into perspective. It’s not the stress in our lives that harms us. It is how we respond to the stress. This study did not measure stress, per se. It measured depression, anxiety, and cortisol levels associated with the stress.

Some of the women in this study had very low levels of all three. It wasn’t that they led stress-free lives. They simply coped better with stress. So, the real question isn’t how to minimize stress. It’s how to better cope with stress. Here are some suggestions.

1) Take time to relax. What you do with this time will be different for each of you. Think about what kind of activity relaxes you the most. Here are some suggestions.

    • Meditation or prayer.
    • Yoga or Tai chi.
    • Watching a comedy.
    • Listening to your favorite music.

2) Make time for hobbies. Again, these would be different for each of you. They should be something that you enjoy and engages your mind. Examples include:

    • Reading.
    • Creating your favorite art. It could be painting, pottery, or knitting, for example.
    • Playing your favorite sport such as golf or tennis.
    • Doing puzzles.
    • Playing cards or board games.
    • Watching a movie.

3) Exercise on a regular basis. Exercise produces endorphins that elevate your mood. It’s even better if you are exercising outdoors so you can enjoy nature or listening to your favorite music while you exercise.

4) Relax your muscles. This is particularly important after you have exercised. Examples include:

    • Do some stretching exercises.
    • Take a luxurious hot bath.
    • Set a regular time to go to bed and get a good night’s sleep.
    • Get a massage.

5) Eat a healthy diet. Studies have shown that people who eat lots of junk and processed foods tend to be depressed and anxious. Aim for a whole food diet with lots of fruits and vegetables. That kind of diet is best for your baby as well.

6) Try deep breathing exercises.

7) Ask for support from your family members, especially if they are stressors in your life.

8) Talk with someone. Find a friend or family member who is willing to listen and support you.

In short, take care of yourself. Don’t let stress affect your health and the health of your baby.

The Bottom Line

Pregnancy can be a stressful time, especially if you are a first-time mom. Plus, we are living in the most stressful time any of us can remember. That is why a recent study is particularly relevant.

Simply put, the study showed that chronic stress during pregnancy increases populations of gut bacteria in the newborn that are associated with adverse health outcomes in children. More studies are needed to confirm and understand this observation, but it raises an issue that is often ignored.

However, let’s put it into perspective. It’s not the stress in our lives that harms us. It is how we respond to the stress. This study did not measure stress, per se. It measured depression, anxiety, and cortisol levels associated with the stress.

Some of the women in this study had very low levels of all three. It wasn’t that they led stress-free lives. They simply coped better with stress. So, the real question isn’t how to minimize stress. It’s how to better cope with stress.

For more details and a discussion on how to cope with stress, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

Does Maternal Vitamin D Affect Childhood ADHD?

Can ADHD Be Prevented?

vitamin dIf you are pregnant, or of childbearing age, should you be supplementing with vitamin D? Increasingly, the answer appears to be yes.

1) Based on blood 25-hydroxy vitamin D levels (considered the most accurate marker of vitamin D status):

    • 8-11% of pregnant women in the US are deficient in vitamin D (<30 nmol/L).
    • 25% of pregnant women have insufficient vitamin D status (30-49 nmol/L).

In short, that means around 1/3 of pregnant women in the US have insufficient or deficient levels of vitamin D. The effect of inadequate vitamin D during pregnancy is not just an academic question.

2) The Cochrane Collaboration (considered the gold standard for evidence-based medicine) has recently concluded that supplementation with vitamin D reduces the risk of significant complications during pregnancy.

3) Another recent study found that inadequate vitamin D status during pregnancy delayed several neurodevelopmental milestones in early childhood, including gross motor skills, fine motor skills, and social development.

If neurodevelopmental milestones are affected, what about ADHD? Here the evidence is not as clear. Some studies have concluded that vitamin D deficiency during pregnancy increases the risk of ADHD in the offspring. Other studies have concluded there is no effect of vitamin D deficiency on ADHD.

Why the discrepancy between studies?

  • Most of the previous studies have been small. Simply put, there were too few children in the study to make statistically reliable conclusions.
  • Most of the studies measured maternal 25-hydroxyvitamin D levels in the third trimester or in chord blood at birth. However, it is during early pregnancy that critical steps in the development of the nervous system take place.

Thus, there is a critical need for larger studies that measure maternal vitamin D status in the first trimester of pregnancy. This study (M Sucksdorff et al, Journal of the American Academy of Child & Adolescent Psychiatry, 2020, in press) was designed to fill that need.

How Was The Study Done?

Clinical StudyThis study compared 1,067 Finnish children born between 1998 and 1999 who were subsequently diagnosed with ADHD and 1,067 matched controls without ADHD. There were several reasons for choosing this experimental group.

  • Finland is among the northernmost European countries, so sun exposure during the winter is significantly less than for the United States and most other European countries. This time period also preceded the universal supplementation with vitamin D for pregnant women that was instituted in 2004.

Consequently, maternal 25-hydroxyvitamin D levels were significantly lower than in most other countries. This means that a significant percentage of pregnant women were deficient in vitamin D, something not seen in most other studies. For example:

    • 49% of pregnant women in Finland were deficient in vitamin D (25-hydoxyvitamin D <30 nmol/L) compared to 8-11% in the United States.
    • 33% of pregnant women in Finland had insufficient vitamin D status (25-hydroxyvitamin D 30-49.9 nmol/L) compared to 25% in the United States.
  • Finland, like many European countries, keeps detailed health records on its citizens. For example:
    • The Finnish Prenatal Study collected data, including maternal 25-hydroxyvitamin D levels during the first trimester), for all live births between 1991 and 2005.
    • The Care Register for Health Care recorded, among other things, all diagnoses of ADHD through 2011.

Thus, this study was ideally positioned to compare maternal 25-hydroxyvitamin D levels during the first trimester of pregnancy with a subsequent diagnosis of ADHD in the offspring. The long-term follow-up was important to this study because the average age of ADHD diagnosis was 7 years (range = 2-14 years).

Does Maternal Vitamin D Affect Childhood ADHD?

Child With ADHDThe answer to this question appears to be a clear, yes.

If you divide maternal vitamin D levels into quintiles:

  • Offspring of mothers in the lowest vitamin D quintile (25-hydroxyvitamin D of 7.5-21.9 nmol/L) were 53% more likely to develop ADHD than offspring of mothers in the highest vitamin D quintile (49.5-132.5 nmol/L).

When you divide maternal vitamin D levels by the standard designations of deficient (<30 nmol/L), insufficient (30-49.9 nmol/L), and sufficient (≥50 nmol/L):

  • Offspring of mothers who were deficient in vitamin D were 34% more likely to develop ADHD than children of mothers with sufficient vitamin D status.

The authors concluded: “This is the first population-based study to demonstrate an association between low maternal vitamin D during the first trimester of pregnancy and an elevated risk for ADHD diagnosis in offspring. If these findings are replicated, they may have public health implications for vitamin D supplementation and perhaps changing lifestyle behaviors during pregnancy to ensure optimal maternal vitamin D levels.”

Can ADHD Be Prevented?

Child Raising HandI realize that this is an emotionally charged title. If you have a child with ADHD, the last thing I want is for you to feel guilty about something you may not have done. So, let me start by acknowledging that there are genetic and environmental risk factors for ADHD that you cannot control. That means you could have done everything right during pregnancy and still have a child who develops ADHD.

Having said that, let’s examine things that can be done to reduce the risk of giving birth to a child who will develop ADHD, starting with vitamin D. There are two aspects of this study that are important to keep in mind.

#1: The increased risk of giving birth to a child who develops ADHD was only seen for women who were vitamin D deficient. While vitamin D deficiency is only found in 8-11% of pregnant mothers in the United States, that is an average number. It is more useful to ask who is most likely to be vitamin D deficient in this country. For example:

  • Fatty fish and vitamin D-fortified dairy products are the most important food sources of vitamin D. Fatty fish are not everyone’s favorite and may be too expensive for those on a tight budget. Many people are lactose intolerant or avoid milk for other reasons. If you are not eating these foods, you may not be getting enough vitamin D from your diet. This is particularly true for vegans.
  • If you have darker colored skin, you may have trouble making enough vitamin D from sunlight. If you are also lactose intolerant, you are in double trouble with respect to vitamin D sufficiency.
  • Obesity affects the distribution of vitamin D in the body. So, if you are overweight, you may have low 25-hydroxyvitamin D levels in your blood.
  • The vitamin D RDA for pregnant and lactating women is 600 IU, but many multivitamin and prenatal supplements only provide 400 IU. If you are pregnant or of childbearing age, it is a good idea to look for a multivitamin or prenatal supplement that provides at least 600 IU, especially if you are in one of the high risk groups listed above.
  • Some experts recommend 2,000 to 4,000 IU of supplemental vitamin D. I would not recommend exceeding that amount without discussing it with your health care provider first.
  • Finally, for reasons we do not understand, some people have a difficult time converting vitamin D to the active 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D in their bodies. If you are pregnant or of childbearing age, it is a good idea to have your blood 25-hydroxyvitamin D levels determined and discuss with your health care provider how much vitamin D you should be taking. Many people need more than 600 IU to reach vitamin D sufficiency status.

#2: Maternal vitamin D deficiency has a relatively small effect (34%) on the risk of the offspring developing ADHD. That means assuring adequate vitamin D status during pregnancy should be part of a holistic approach for reducing ADHD risk. Other factors to consider are:

  • Low maternal folate and omega-3 status.
  • Smoking, drug, and alcohol use.
  • Obesity.
  • Sodas and highly processed foods.

Alone, each of these factors has a small and uncertain influence on the risk of your child developing ADHD. Together, they may play a significant role in determining your child’s risk of developing ADHD.

In closing, there are three take-home lessons I want to leave you with:

1) The first is that there is no “magic bullet”. There is no single action you can take during pregnancy that will dramatically reduce your risk of giving birth to a child who will develop ADHD. Improving your vitamin D, folate, and omega-3 status; avoiding cigarettes, drugs, and alcohol; achieving a healthy weight; and eating a healthy diet are all part of a holistic approach for reducing the risk of your child developing ADHD.

2) The second is that we should not think of these actions solely in terms of reducing ADHD risk. Each of these actions will lead to a healthier pregnancy and a healthier child in many other ways.

3) Finally, if you have a child with ADHD and would like to reduce the symptoms without drugs, I recommend this article.

The Bottom Line

A recent study looked at the correlation between maternal vitamin D status during the first trimester of pregnancy and the risk of ADHD in the offspring. The study found:

  • Offspring of mothers who were deficient in vitamin D were 34% more likely to develop ADHD than children of mothers with sufficient vitamin D status.

The authors concluded: “This is the first population-based study to demonstrate an association between low maternal vitamin D during the first trimester of pregnancy and an elevated risk for ADHD diagnosis in offspring. If these findings are replicated, they may have public health implications for vitamin D supplementation and perhaps changing lifestyle behaviors during pregnancy to ensure optimal maternal vitamin D levels.”

In the article above I discuss what this study means for you and other factors that increase the risk of giving birth to a child who will develop ADHD.

For more details read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

 

The Effect Of Vitamin D On Childhood Development

Is Vitamin D Important During Pregnancy?

vitamin dIf you are parents, you want the best for your child. It can be nerve wracking when your child doesn’t meet the expected developmental milestones. When I saw a recent study titled “Association of maternal vitamin D status in pregnancy and neurodevelopmental outcomes in children” ( AL Darling et al, British Journal of Nutrition, 117: 1682-1692, 2017), I knew you would want to hear about it.

But first a bit of background: Based on blood 25-hydroxy vitamin D levels (considered the most accurate marker of vitamin D status):

  • 8-11% of pregnant women in the US are deficient in vitamin D (<30 nmol/L).
  • ~25% of pregnant women have inadequate vitamin D status (30-49 nmol/L).
  • ~65% of pregnant women have adequate vitamin D status (50-125 nmol/L).
  • ~ 1% of pregnant women have high vitamin D levels (>125 nmol/L).

In short, that means around 1/3 of pregnant women in the US have inadequate or deficient levels of vitamin D. The affect of inadequate vitamin D during pregnancy is not just an academic question.

It is a concern because inadequate vitamin D levels during pregnancy has been associated with gestational diabetes (diabetes during pregnancy), low birthweight babies, and a condition called pre-eclampsia (pre-eclampsia is characterized by the development of high blood pressure during pregnancy and can lead to serious, even fatal, complications for mother and baby).

The Cochrane Collaboration (considered the gold standard for evidence-based medicine) has recently reviewed the literature and has reported) that vitamin D during pregnancy “probably reduces the risk of pre-eclampsia, gestational diabetes, and the risk of having a low birthweight baby compared to placebo or no intervention.”

In short, this means the evidence is pretty good that inadequate vitamin D increases the risk of significant complications during pregnancy and that supplementation with vitamin D reduces the risk of those complications.

However, what about the effect of inadequate vitamin D during pregnancy on the development of the newborn child? Here the evidence is less clear. This study was designed to answer that question.

How Was The Study Designed?

clinical studyThis study followed neurodevelopmental milestones of 7065 children born to mothers in the Avon region of southwest England between April 1, 1991 and December 31, 1992. Maternal 25-hydroxy vitamin D levels were measured during pregnancy. The distribution of 25-hydroxy vitamin D levels in this population was very similar to that observed for pregnant mothers in the United States.

The children were followed from 6 months to 9 years of age and the following neurodevelopmental milestones were measured:

  • Gross-motor skills, fine-motor skills, social development, and communication skills were measured at 6, 18, 30, and 42 months.
  • Behavioral development (socialization, hyperactivity, emotional development, and conduct) was measured at 7 years.
  • IQ was measured at 8 years.
  • Reading skill (words/minute, accuracy, and comprehension) was measured at 9 years.

What Is The Effect Of Vitamin D On Childhood Development?

Child raising handThe study compared children of women who had inadequate vitamin D status (<50 nmol/L) during pregnancy to children of women who had adequate vitamin D status (≥50 nmol/L) during pregnancy. Here is what the study found:

The children of mothers with inadequate vitamin D during pregnancy had:

  • Delayed gross-motor skills at 18 and 30 months.
  • Delayed fine-motor skills at 30 and 42 months.
  • Delayed social development at 42 months.

However, when they looked at later years, there was no significant effect of maternal vitamin D status on:

  • Behavioral development at 7 years.
  • IQ at 8 years.
  • Reading skills at 9 years.

This is encouraging because it suggests that the effect of inadequate vitamin D during pregnancy does not have a permanent effect on childhood development. By the time they are 7 or older their nutrition and intellectual stimulation during childhood appears to outweigh the effect of their mother’s nutrition on their development.

In interpreting this information, we need to keep in mind that this study was performed in England, not in a third world country. In particular:

  • England, like the United States, has supplemental food programs for disadvantaged children.
  • England has an excellent educational system. So, we can assume these children also received intellectual stimulation as soon as they reached school age.

Is Vitamin D Important During Pregnancy?

pregnant women taking vitaminIf we focus on a healthy pregnancy, there is good evidence that inadequate vitamin D during pregnancy increases the risk of serious complications and that supplementation with vitamin D can reduce these complications. We also know that vitamin D deficiency during pregnancy can affect bone development in the newborn.

Thus, adequate vitamin D is clearly needed for a healthy pregnancy.

However, if we just consider the effect of maternal vitamin D on childhood development, it would be tempting to downplay the importance of vitamin D during pregnancy. This study focused on vitamin D, but studies focusing on other nutritional deficiencies usually give similar results.

In most of these studies, the effects of inadequate nutrition during pregnancy on childhood developmental milestones appear to be transient. Developmental delays are seen during the first few years of life but disappear as the children get older.

This is incredibly good news. It means that mild nutritional deficiencies during pregnancy do not have to handicap a child for life. If the children are given adequate nutrition and intellectual stimulation as they grow, the poor start they received in life can be erased.

It is also a caution. We already know that poor nutrition during childhood can affect a child’s behavior and intellectual development. If that child also received poor nutrition in the womb, their chances of normal childhood development may be doubly impacted.

In short, if adequate vitamin D during pregnancy improves early developmental milestones in children, that can be viewed as an added benefit.

The only question is how much vitamin D is needed. Fortunately, the present study cast some light on that question.

The study asked whether blood levels of 25-hydroxy vitamin D ≥75 nmol/L were more beneficial than blood levels ≥50 nmol/L. The answer was a clear no. That means an adequate vitamin D status during pregnancy is sufficient to support normal developmental milestones in children.

The current recommendation (DV) of vitamin D3 for pregnant women is 15 mcg (600 IU). Thus, my recommendations are:

  • If you are pregnant, be sure that your prenatal supplement provides at least 600 IU of vitamin D3.
  • If you are a woman of childbearing age, be sure that your multivitamin provides at least 600 IU of vitamin D3.
  • Slightly more is OK but avoid mega doses unless prescribed by a health professional who is monitoring your 25-hydroxy vitamin D status.
  • Because we all utilize vitamin D with different efficiencies, I would recommend asking for a 25-hydroxy vitamin D test and working with your health professional to keep your levels in the adequate range.

The Bottom Line

A recent study looked at the effect of mild vitamin D deficiency during pregnancy on childhood developmental milestones. The study found that children born to vitamin D-deficient mothers had:

  • Delayed gross-motor skills at 18 and 30 months.
  • Delayed fine-motor skills at 30 and 42 months.
  • Delayed social development at 42 months.

This is concerning. However, when they looked at later years, there was no significant effect of maternal vitamin D status on:

  • Behavioral development at 7 years.
  • IQ at 8 years.
  • Reading skills at 9 years.

The is encouraging. The reasons for this are discussed in the article above.

If we summarize this and previous studies, the bottom line is:

  • Adequate vitamin D is clearly needed for a healthy pregnancy.
  • If adequate vitamin D during pregnancy improves early developmental milestones in children, that can be viewed as an added benefit.

For more details and my recommendations on how much vitamin D you need, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Health Tips From The Professor