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Fluoride in early pregnancy
Uses of fluoride that relate to preventing birth defects in a general sense

Home | Other known ways to possibly prevent birth defects | Popular uses of fluoride | Uses of fluoride that relate to preventing birth defects in a general sense | Fluoride and specific birth defects - heart, ear, and mouth | Evidence and support for using fluoride in early pregnancy | How to use fluoride in early pregnancy | A chance to help - a questionnaire | Contact Me


There are books about preventing birth defects that recommend various fluoride rich foods such as canned salmon, but as a source of calcium (or iron), not as a source of fluoride. (For example, The Healthy Baby Book, A parents guide to preventing birth defects , Reuben 1992, page 61.) However, it is well known that these foods are rich in fluoride, and in other places (books about fluoride for teeth and bones) canned fish is often recommended as a source of fluoride.


There is an obscure area of fluoride research that was very helpful to me. Our ancestors, the earliest hunters and gatherers, had fluoride intakes vastly greater than we do today.


Fluoride is usually in the rougher-tougher parts of foods. For an extreme example, the whole grain that cows eat has about 100 times the fluoride of the bread that we eat. The same is true between their pasture grass and our vegetables like broccoli. Many foods are of course the same (an apple is an apple, gathered or bought). In total, a reasonable estimate is that hunters and gatherers got about 5 times the fluoride of modern people.


There was at least one group of hunters and gatherers who got enough fluoride to cause fluorosis. This was in the South Pacific, in the Austral Islands. "The inhabitants of the Australes and Savaii continue to eat traditional Polynesian food. From this, particularly fish, taro root, and coconut, they absorb sufficient dietary fluorides to produce slight mottling of their permanent teeth. A recent survey (1970) of the school age population of the Australes show an incidence of 90% of mild white flecked fluorosis and of 6% moderate brown flecked fluorosis." The author was also comparing the teeth of the natural-living islanders to the teeth of Tahitians who had a more modern diet. The saddest of the modern cases was a bevy of beautiful teenaged girls who had no teeth left at all.


(The source is Baume, 1970. Arch Oral Biol 15:431; and Indent 1(3):36. The water fluoride level in the Australes was .5 ppm. That is fairly high relative to most easy-to-get water. Artificially fluoridated water is usually 1 ppm. If the water fluoride is much higher than 1 ppm, it starts causing fluorosis. See any book on fluoride for more details on water fluoride.)


A common misconception is that if we were hunters and gatherers we would die by about age 30 because our teeth would rot out. Nothing could be farther from the truth. Almost any book on anthropology will tell you that it was hard to find so much as a trace of decay before agriculture was adopted. In fact, that is how they tell that people had started farming - their teeth started showing small areas with weak enamel called enamel defects, and traces of decay. Even with primitive agriculture, many groups still had almost zero decay. This was especially true if they lived near the sea (seafood is very rich in fluoride).


The other thing primitive people did not have was what we call malocclusion, or crooked teeth. Burials have been found with thousands of skulls with not a single tooth out of line. I want to mention that a few anthropologists have specifically looked, and could find no evidence that primitive people had birth defects. That could obviously be simply because the evidence does not preserve well.


There is a book that thoroughly tells the story of how peoples teeth changed when their diets changed from primitive to modern. It is called Nutrition and Physical Degeneration, by Weston A. Price, DDS. There are striking photographs and lots of details. The interesting thing is that the changes happened not so much to the first people to eat modern food, but to their children who were conceived, born, and raised on it. The older generation, even the very oldest, had fine sets of teeth. The children had both rampant dental caries and crooked teeth - and a whole litany of other health problems.  (We will come back to these hunters and gatherers.)


By a quirk of fate there is also a story about a group of people whose diets changed the other way. A group of modern settlers got stranded on an island, Tristan da Cunha, for a few decades when shipping routes changed. When they were found their children had near-perfect teeth. Increased fluoride in their diet was given the credit. (Sognnaes 1941, Journal of Dental Research  20:16.) When they once again returned to modern foods, the new kids born had rotten teeth. (Rosevear 1993, PPNF Nutrition Journal  17(1):12.)


Over a century ago, the first major medical author to recommend adding fluoride to the diet of childbearing women and children (this would include early pregnancy) saw an uncanny correlation between dental decay, crooked teeth, narrow jaws, high-arched palates, and mental retardation. (Sir Crichton-Browne 1892, Lancet  July 2; 17(2):6.)


The first nutrient supplement ever used specifically to prevent birth defects, in cows, not humans, as cited in the first major scientific book specifically about how nutrition affects birth defects, was bone meal. (Hurley 1982, Developmental Nutrition.) (Bone meal is a known source of fluoride.) (A historical note is that this work was done by the group that developed the idea of nutrient deficiency diseases. They isolated most of the vitamins and a few mineral deficiencies back in the 1920's and 30's. Some of them dabbled in fluoride for other reasons, and one even used to give talks with a dentist, but none of them expressed any interest in finding what it was in bone meal that prevented the birth defects.)


Prenatal fluoride (PNF) is now used by about 10% of doctors to prevent dental caries. Typically, fluoride is prescribed starting about the 3rd month of pregnancy. This is when teeth start forming but it is after the critical period for birth defects. In the most widely cited study on PNF it is stated:  "there were no medical or dental defects in the 117 PNF children in this series and, indeed, none in the total 412 PNF children in this practice."  (Glenn 1982, American Journal of Obstetrics and Gynecology 143:560.)


Fluoridated water does not supply enough fluoride in pregnancy. The main trial of PNF (above) is in a fluoridated area, and these kids are clearly getting a profound benefit from the extra fluoride in PNF. Conversely, teeth that form in pregnancy with only fluoridated water still get plenty of decay. Studies show much less benefit from fluoridated water in pregnancy (10 35% reduction in decay in the baby teeth) compared to the almost 100% reduction shown from a fluoride supplement.


There is some evidence that fluoride may help prevent crooked teeth (malocclusion).  (Moller IJ, 1965. Dental Fluorose Og Caries. Rhodos. (Danish with English summary and tables.) Moller's review of 5 studies concludes that, Most authors seem to agree that the prevalence of malocclusion is less in fluoride areas than in low-fluoride areas. His own study from 4 areas in Denmark found that the higher the fluoride in the water, the more children had straight teeth (% of 12 year olds with normal tooth position went up from 56.1% when the water had .05 ppm F up to 74.15% when the water had 1.9 ppm F, P<.05). A few years later another review was more neutral: WHO, 1970. Fluorides and Human Health. Page 351.)


The shape of the jaw, which most logically makes the most difference between straight and crooked teeth, is set very early in pregnancy and has almost nothing to do with heredity. (The spacing of teeth can be seen by the 11th week of pregnancy. Garn 1979, Journal of Dental Research 58(2):554.) Whenever the spacing is set, it is before prenatal fluoride is started, and prenatal fluoride does not do anything for crooked teeth (remember the braces?) (see page before). In a sense, the most dramatic difference between prenatal fluoride kids and hunters and gatherers is the shape of the jaw. Both groups have zero cavities, but the prenatal fluoride kids do not have the perfectly straight teeth seen in the hunters and gatherers. The big difference in these two groups is when they start their fluoride. This was a profound clue for me.


To my knowledge the closest anyone has come to suggesting that fluoride in early pregnancy could help prevent narrow jaws was by the author of the book (way above) about what happened when hunters and gatherers changed to modern foods. Price suggested that something fresh from the sea every day could prevent both the dental decay and the narrow jaw problems seen with modern diets. (Price 1935, Dental Cosmos 77(11):1033.)


A historical note is that during the 1930's many mineral deficiencies were discovered. In 1939, a team led by a public health dentist, H. Trendly Dean, compared the dental caries in towns with high fluoride (~1.8 ppm) and low fluoride (.2 ppm) water. The report is long, detailed, and very well supported. The kids are 12-14 yrs old and lived in the towns their whole lives. My favorite quote: "These differences are so great that little comment seems necessary. The 2,718 surfaces in the [high fluoride] children showed only 0.59 carious lesion per 100 surfaces. In the 2,814 tooth surfaces of the [low fluoride] children there were 8.9 carious lesions per 100 surfaces, or 16 times as much." (Public Health Reports 1939, 54:862-888.)


This was the first major fluoride-prevents-cavities report in history. It reverberated throughout the dental community, where Price (a dentist) was a major author and editor. Shortly thereafter followed the first official U.S. recommendation to use fluoride supplements for preventing tooth decay, by McClure in 1943, and the first artificial fluoridation of water, by public health dentists in 1945 and the formation of anti-fluoridationist groups by other dentists.


Then, Price, who had not mentioned fluoride in his 1939 book, brought out a new edition in 1945. The main change was adding a chapter on fluoride. It has the following to say about the changes in primitive diets that led to rampant dental decay and widespread crooked teeth:  "the reduction in fluorine intake, if any, was limited to the lowered use of sea foods and land plants". (Page 471.) He said that F presumably had a part in vital phenomena [of plant and animal life], and notes some of his experiments where it stimulated plant growth up to 10 ppm. Price's chapter is otherwise classic anti-fluoride (no mention of useful things like Dean's work above, and lots on fluorosis, dental office dips, and admonitions not to add fluoride to food or water). Price's followers today are still a source of anti-fluoride literature. (Price was also torn in a tragic personal sense. His only son died early in his teens from a heart defect, and much of Price's most creative work was dedicated to his son.)


The closest thing to an absolute defect that is absolutely prevented by fluoride in the literature is from the prenatal fluoride studies of Glenn. There is a very common defect of molar teeth, called pits and fissures. The pits and fissures of the primary molars form at about the 5th month of pregnancy and show when these teeth erupt at about 2 years. Without extra fluoride in pregnancy most children (97%) have pits and fissures to some degree on at least one tooth. Of the total individual teeth, 28% have at least one very large pit. Prenatal fluoride makes a black and white change: only 2% of children have any sign of pits and fissures, and none of the individual teeth has a large pit. (Glenn 1984, ASDC Journal of Dentistry for Children 51:19.) It was trying to understand this paper by Glenn that got me started.


How? How does fluoride make such a radical and complete change in the shape of a tooth? Although people do not think of them that way, teeth are organs. A change in the shape of an organ is a substantial biological change. Teeth, like almost all organs and most body parts, are formed by a layer of cells that are wrapped around and guided by a tissue called the mesenchyme (or mesoderm, or mes for short, pronounced mez). You can't "see" the future organ in the mes, which looks like a chaotic mess of cells and lots of matrix. But you can recognize the future organ as soon as the cells around the mes start to get organized.


During organ formation, the cells essentially grow out, sort of like an expanding balloon, making an organ on the inside. The growth signals from the mes are what controls the whole growth process. When the growth is done, or rather when the mes says it is done, the mes fades away and the cellular layer stops growing the organ. Fluoride affects these growth signals from the mes, basically slowing them down. In teeth the mes tissue has about twice the affinity for fluoride, so adding fluoride would tend to slow the mes down more than it would the cellular layer. Pits and fissures, and many birth defects, appear to be closure defects that are caused by not getting quite enough time to finish before the mes fades away.


For example, the defects prevented by folic acid, neural tube defects, can be visualized as either running out of folic acid or running out of time. Folic acid is critical to make new cells. New cells cannot be made without it. In order for the neural tube to close, it needs lots of new cells. The cellular layers wrapped around the mes that do the actual growing do it by multiplying cells. But there is only a small window of time to get these cells made. If the mes moves away too fast, it closes the window before the cells can close the growth process by joining at the seam.


Mes is a dominant issue in birth defects. Other than a few causes of birth defects like folic acid deficiency, the vast majority of known causes of birth defects have something to do with the mes or signals from it.


(Citations for "mes": For teeth growth see Schour 1940, Journal of the American Dental Association 27:1778 and 1918; for mes control of organ growth, see Sawyer 1983, Epithelial-Mesenchymal Interactions in Development; for fluoride effects on mes growth signals see Kerley 1977, American Journal of Anatomy 149(2):181.)


For me personally, seeing the likelihood that fluoride could slow down the growth signals from the mes was the single most important clue.


A dentist can spot pits and fissures, as that is part of the decision to use sealants to prevent caries. However, a parent, or even a pediatrician, will probably not have an eye for it. The easiest thing to use - based on logic, not proof - is the appearance of the front teeth that show at about age 6 months. If these teeth are saw-toothed, (have 3 bumps, as opposed to being flat, across the top), they were probably formed with less than optimum fluoride.


A most pleasant indicator of fluoride status is the appearance of the enamel. Fluoride makes a dramatic difference at every level, all the way down to the sub-microscopic. What you can see with the naked eye are color and texture. Fluoride makes the enamel whiter and have a texture that looks like the inside of a sea shell. (LeGeros 1985, Journal of Dental Research  64(3):465, and Feltman 1961 Journal of Dental Medicine  16(4):190.) (You can see some gorgeous teeth and enamel close-ups on my infant fluoride site. The enamel close-ups are on the page titled Physical effects of fluoride.)


There are a few pieces of evidence that fluoride is a plus for overall growth. In Glenn's trial prematurity was reduced from 13.2% to 1.9%, and birth weights were 6% higher. Low birth weight is linked to slightly lower fluoride in body tissues. (Hellstrom 1976. Scandinavian Journal of Dental Research ; 84(3):119-36.)




In summary, the literature shows that the general effects of fluoride in pregnancy are:


1. Malocclusion is probably reduced. (This one is an early pregnancy effect.)

2. Tooth enamel is more attractive.

3. Enamel defects are reduced.

4. Major pits and fissures are reduced from 28% to zero.

5. Birth weight may be increased by about 6%.

6. Dental decay is reduced to zero. (This one could also be from continuing fluoride after pregnancy.)



There are also reports on the safety of fluoride in early pregnancy. Although the evidence is far from conclusive, it appears that humans can tolerate high doses of fluoride in early pregnancy without causing a noticeable increase in birth defects. There are places where pregnant women get a daily average fluoride intake of about 20 mg F with no known problems with birth defects. (Teotia 1979, Fluoride 12(2):58.)


Animal experiments do not indicate that fluoride is teratogenic at any dose. Although not a birth defects study per se, the best example is in dairy cattle fed doses of fluoride that went from normal to extremely excessive. Essentially, all of the normal signs of excess fluoride (which means teeth are affected first, then hair and bone problems) appeared, but the signs of reproductive health (fertility, % of live births, and gestation time) all went slightly up and seemed to peak just before the highest dose. The highest dose tested was 2.5 mg/kg, or the equivalent of over 150 mg F for a 140 LB woman. (Newell  1958, Am J Vet Res 19: 363-76.)


Common sense says that in spite of these high doses are safe reports, it would be stupid to take high doses just because bad effects havent been noticed. It would be far more logical to stay close to the doses that have been shown to be good for teeth.


The time that the utmost care should be taken to not give too much fluoride is during infancy. This is when the permanent "smile teeth" are being formed. A little too much can cause white spotting and large overdoses will turn teeth a hideous shade of brown. High fluoride areas (including those that did not have birth defects) have some mighty ugly teeth. (Fejerskov 1988, Dental  Fluorosis - a handbook for health workers.)


(I recommend .033 mg/kg F supplemental fluoride for infants, adjusted for major sources such as formula made with fluoridated water. My company makes medicine droppers with body weight scales that deliver precise dosages. See link at the bottom of the previous page.)


An 8 oz glass of fluoridated water supplies .25 mg F. The adult intake of fluoride considered to be "safe and adequate" by the National Academy of Sciences is from 1.5 to 4.0 mg F per day. This range is not reached by adults in non-fluoridated areas, where the estimate on fluoride intake is about 1.0 mg F per day. This range is said to be easily met in fluoridated areas, where the estimated intake is about 4.0 mg F. (1980 RDAs, page 156.) However, the World Health Organization has said that fluoridated water provides a level of fluoride ingestion that is regarded as optimal for the mother [but that] is of borderline significance for the expected child [for protecting the baby teeth from dental decay]. (WHO 1970, Fluorides and Human Health, page 342.)


It is known that the mothers blood and urine levels of fluoride drop dramatically and steadily during the course of pregnancy. In very high fluoride areas, the urine level drops by over half (55.3%) by the end of pregnancy. The drop is even greater (64.7%) in areas with normally fluoridated water. There are no data given for low fluoride areas. (See Teotia reference above.) (There are two implications to this. First is that the fluoride is being used by the mothers rapidly changing body and / or the rapidly growing fetal body. Second is that there seems to be no upper limit to how much fluoride a fetus could get. Fluorosis of baby teeth - i.e., solid proof of a fluoride overdose in pregnancy - is rare, but it has been observed. There is a picture in the Fejerskov book above.)


The most complicated science of human nutrition is total parenteral nutrition, or TPN. In TPN doctors are 100% responsible for nutrition because every thing a patient eats comes predigested, through a tube, straight into the blood stream. TPN is used in various conditions that do not allow the use of the patients' digestive tract.


There have been a few pregnancies reported during TPN. In at least a few of these pregnancies fluoride was began as soon as pregnancy was detected, including early pregnancy. In one of these the fluoride (1 mg) was began at about day 49. When the child of this pregnancy was born, it had what was thought to be partial cleft lip. That hit me like a ton of bricks, since the time the fluoride was started was right in the middle of the time cleft lips form.


If an embryo with a cleft lip beginning is aborted on day 42, the cleft lip is visible microscopically. I think the cleft lip may have been forming from day 42 until the fluoride was started on day 49, and that is why the child ended up with a partial cleft lip instead of a full blown one. (Unfortunately this article does not say which side of day 49 the cleft is on. I have written but not gotten an answer.) (Mughal 1987, British Journal of Obstetrics and Gynaecology  94:44.)

My site with some drawings of the biology - this is as deep as I go. The URL is

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