The Changing Relationship Between Obesity and Vitamin D in Pregnancy

Mothers who are overweight and obese at the beginning of their pregnancies can cause health problems for their unborn children. They may not have sufficient amounts of vitamin D to pass on to their babies. This is the worrying conclusion of piece of research from Northwestern Medicine.

This research discovered that babies of leaner mothers had almost one-third more of the required vitamin D than did the babies born to heavier mothers. Vitamin D dissolves in fat. Other studies have already informed us that overweight individuals and especially those classified as  obese generally are deficient in levels of vitamin D in their bloodstream.


This latest research adds to our knowledge in that all of the pregnant women had roughly equivalent levels of vitamin D towards the final stages of pregnancy. But the bigger mothers passed less of their vitamin D to their babies in comparison to slimmer women. Almost all of the women in this research, were aware of the benefits and took extra vitamins specially for pregnancy. This certainly helped to explain the adequate levels of vitamin D at the start of the gestation period. But the fact remains that insufficient levels of the vitamin made the transition to the children of the overweight mothers. One possibility is that the vitamin gets absorbed into the excess body fat of the overweight women and thereby withheld from the fetus.

The dangers inherent in child deficiency of vitamin D are well documented. They all stem from an underdeveloped autoimmune system and result in higher risk factors for all kinds of disease, inflammation in a continuation of obesity into the next generation. The researched can be read in the January 4 ‘Journal of Clinical Endocrinology and Metabolism’. They are interim conclusions from a much longer term study that is looking into the role of body fat in pregnancy and infant health. As well as development in older children and young adults.

Because of the essential role vitamin D plays in general health terms, and especially it’s link to obesity, the scientists made a point of focusing on vitamin D levels in both the mothers and their babies. 61 pregnant women who had their babies at Prentice Women’s Hospital of Northwestern Memorial Hospital in Chicago took part in the study. They were all subject to accurate body mass indices measurement before their pregnancies and were in two categories; normal or obese.

Blood tests including their vitamin D levels were then conducted with samples from the pregnant women at 2 week intervals during the final month of gestation. Blood samples were tested from the umbilical cord of the new-borns just minutes after their births. All of the usual infant measurements were taken, such as body fat, weight, and volume as well as air displacement plethysmography with the Pea Pod Infant Body Composition System. These were correlated with the measure from the mothers.

The variations in body fat between the infants in this research was no different to other studies reporting new-born body fat. What was different this study was the link found between raised vitamin D levels and babies with raised levels of body fat. This is the reversal of the relationship found in children and adults. Normally the more vitamin D the lower the BMI. A great deal more research is needed around the part played by vitamin D in the general health of infants and babies.

Claire Al-Aufi

Claire Al-Aufi is a contributing author for Hive Health Media who provides updates on health and fitness news.

3 thoughts on “The Changing Relationship Between Obesity and Vitamin D in Pregnancy

  • February 14, 2013 at 2:52 am

    I differ from the explanation given by the researchers as to why Vitamin D from the blood of obese mothers does not get to their fetus. The researchers suggested that the dissolution of vitamin D in the excess fat of obese mothers could be responsible for this lack of transition from mother to fetus. I don’t hold that view. Rightly, the researchers stated that vitamin D is a fat-soluble vitamin, implying that for it to be absorbed, it must have to dissolve in fat. So since the mother’s vitamin D has dissolved in the obese mother’s fat (or excess fat) there is no reason why the dissolved vitamin cannot get to the fetus. Even if the vitamin had dissolved in excess fat, the concentration of the vitamin in the mother’s fatty blood would still have been driven by just simple diffusion from mother to fetus, since the level in the fetus is lower. Alternatively, if the transport is by facilitated diffusion, the transport of the vitamin from mother to fetus would still have taken place.

    My gut reaction to this ‘anomaly’ is that something must have happened in the membrane separating mother’s blood and that of the fetus to make this diffusion of vitamin either difficult or impossible. This is the area this research should focus. As they are still in the process of this research they should have to look into this possibility; and I must say, it is a research that should take some time to produce answers!

  • February 12, 2013 at 11:44 am

    I’m to the point whereby I evaluate the quality of a primary care physician partly on whether or not he or she asks me about vitamin D levels, if I’ve been tested or if I supplement. IMO, a good primary care doctor should ask patients these questions during the first visit and monitor the status thereafter.

  • February 12, 2013 at 6:23 am

    It is better to reduce and maintain a healthy body weight before and during the pregnancy. Because, vitamin D is an essential nutrient of the calcium metabolism and is required for bone formation, development of the immunity, and growth of the fetus.


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