Added September 14, 2005:  “Record-High 1.4M Births to Single Women in 2003; Teen Birth Rate Drops for 12th Consecutive Year, Report Says, USA.” Washington Times  In the following explanation of this phenomenon, I do not mention the impact of DHEA.  DHEA is involved in pregnancy.  DHEA peaks around age 20.  This means that the teens have not reached peak levels for pregnancy.  Testosterone interferes with the availability of DHEA.  Therefore, teens will have an unfavorable ratio of DHEA to testosterone for pregnancy.  Since testosterone continues to rise in this country, this means that the teens will continue to exhibit reduced pregnancy and this reduction will increase with time.  As the teens age and their DHEA levels increase, they will begin to increase in pregnancy.  All of the foregoing, added to increased sexuality due to increased testosterone levels, also explains why the older group of women exhibit increased births.


A Possible Explanation of the Decline in Birth Rate Among “Adolescent and Young Teen Girls in the United States” as Well as Other Groups


Copyright 2004, James Michael Howard, Fayetteville, Arkansas, U.S.A.


The birth rate of “adolescent and young teen girls in the United States” has declined to the lowest levels since 1946.  The explanations include abstinence programs and birth control.  Well, this combination may be the reason and this would be positive because it can be continued.  However, there may be another reason for this decline in birth rate.


It is my hypothesis that the “secular trend,” the increase in size and earlier puberty occurring in our children results from increases in testosterone.  That is, the percentage of people of higher testosterone is increasing more rapidly than those of lower testosterone.  (Testosterone, not estrogen, is the source of sexual activity in girls and women.)  Over time the percentage of individuals of higher testosterone increases within the population.  This is driven by the percentage increase in women of higher testosterone and the consequences of this are due to exposure of fetuses to higher maternal testosterone.  The neonates become children who grow bigger and enter puberty earlier, among other phenomena that are also increasing within our population.


If individuals of higher testosterone are increasing in percentage and this is the cause of reduced birth rates, then increased testosterone should be connected with reduced fertility and conception in women and girls.  This is supported.


In this citation, note the effects of testosterone on fertility “in the absence of clinical signs of hyperandrogenism.  In other words, increased testosterone may reduce fertility in women and girls without outward signs of excessive testosterone.  “The mean level of free T [testosterone] was significantly higher (P less than 0.05) in anovulatory women when compared with ovulatory ones. …The results show that in infertile women determination of androgen levels, and especially free T [testosterone], is indicated in the absence of clinical signs of hyperandrogenism.” (Human Reproduction 1988; 3: 437-439).


This next citation supports, again, that high testosterone reduces conception.  “In addition, levels of free testosterone during the follicular phase were significantly lower in women who conceived compared to non-conceptional IVF cycles, whereas levels of total testosterone were similar.” (Human Reproduction 1992; 7: 1365-70).


This effect does not affect women alone.  Too much testosterone reduces spermatogenesis, sperm count, in men.   Testosterone undecanoate increases free testosterone in men.  “Monthly injections of testosterone undecanoate (TU) act as a male contraceptive by reversibly suppressing spermatogenesis to azoospermia or severe oligoazoospermia in 95% of Chinese men.” (Journal of Andrology 2004; 25: 720-7)  I suggest the secular trend, the increase in testosterone, is also affecting men.  This effect may be linear, that is, sperm count may begin to be reduced at a high level of testosterone before actually causing spermatogenesis to cease.  I think this is occurring with the secular trend.


Again, I suggest the secular trend, which is real and robust in our children (“Secular Trends in Height Among Children During 2 Decades,” (Archives of Pediatric and Adolescent Medicine 2000; 154: 155-161), represents an increase in individuals of higher testosterone.  As this increase occurs, we increasingly see the effects of excessive testosterone.  I suggest one of these effects is a reduction in birth rates of individuals of high testosterone because high testosterone reduces fertility / conception in females and reduces sperm count in males.  This may be the cause the decline in teenage birth rates.


Now, as I stated above, the institution which reported these findings regarding teenage birth rates suggested that abstinence programs and contraception may be producing this effect.  If I am correct, then we should be seeing other consequences of increasing testosterone within our population that should not be ameliorated by abstinence programs or contraception.  Autism has been connected with maternal testosterone levels and autism is also increasing within our population.  Testosterone levels have been directly connected with breast cancer.  “…testosterone might be more strongly associated with [breast cancer] risk than estradiol.” ( Journal of the National Cancer Institute (U.S.A.) 2002; 94: 606-616).  Breast cancer is rapidly increasing and has been determined to not be due to increased surveillance.  I also suggest a strong case may be made for the involvement of excessive testosterone with obesity, premature and underweight births, and learning problems, all of which are increasing.