Library of Excerpts

Influences Related to Gestation and Prematurity and their Effects on Maturation Rates

"Females are born with about 2 million egg cells, but fewer than 500 of them will ripen over a lifetime. Human females begin to make viable eggs at about age fifteen and stop at about age fifty....Human males produce about 3,000 tiny gametes a day." (Small, Meredith F. (1993) Female choices: Sexual behavior of female primates. Cornell Univ. Press, Ithaca, 1993 pp. 24)

[abstract] "Pregnancy and delivery complications as indicated in medical records and maternal reports for 23 high-functioning autistic females and 23 high-functioning males of similar IQ and age were compared with those of 54 of their normally developing siblings. Autistic subjects of both sexes had higher non-optimality scores than their siblings. Much of this difference was accounted for by a higher incidence of firstborns and fourth- or later-borns in the autistic group. Of factors found in previous research with mentally handicapped, autistic samples, only estimated weeks of gestation greater than 42 occurred more often in autistic subjects than siblings. The only sex difference specific to the autistic group was that autistic males came from larger families than females. These data provide slight support for the contribution of nonspecific pre- and perinatal factors to other etiological bases of autism. It is proposed that pre- and perinatal factors may play less of a role in autism in high-functioning individuals than suggested in studies of autism associated with severe retardation." (Lord C, Mulloy C, Wendelboe M, Schopler E (1991) Pre- and perinatal factors in high-functioning females and males with autism. J Autism Dev Disord 21(2):197-209)

"There is a fragility to masculinity that causes many different calamities to descend upon them. Males die at a grater rate at all ages, until there are so few left that the female death rate must ascend. It happens in the womb, too: 150 or so males are conceived for every 100 females, and only about 106 are born for every 100, and this is a gigantic biological difference, so it can't be our society that is solely at fault" (Ornstein, R. (1997) The Right Mind. Harcourt Brace & Co: San Diego p. 111)

[citations removed] "With regard to twins, the expression of the rs + gene is less effective in twins than the singleborn, probably because the rate of growth is slowed in utero, and this is true for both monozygotic (MZ) and dizygotic (DZ) pairs. The prediction that twins are less biased to dextality has been strongly supported for hand skill and for hand reference. The widely-held assumption that a genetic influence on handedness requires MZ and DZ twins to differ for the distribution of RR, RL and LL pairs is mistaken. According to RS theory, almost all of the variability for handedness in both types of twin is due to chance, while the genetic influence is virtually constant." (Annette, M. & Alexander, M.P. (1996) Atypical cerebral dominance: predictions and tests of the right shift theory. Neuropsychologia 34 (12): 1225)

"Early on in utero the brain turns in the skull. The left hemisphere twist back and the right hemisphere twists forward at 34 weeks." (Ornstein, R. (1997) The Right Mind. Harcourt Brace & Co: San Diego p. 149)

"There have been a number of recent studies that have observed that left-handedness is more prevalent in samples of individuals who have experienced stressful births. Individuals with a history indicating premature birth, prolonged labor, low birth weight, RH incompatibility, breech delivery, multiple birth, and several other birth stessors are more likely than others to deviate from the population norm of right-handedness. (Ashton, 1982; Badian, 1983; Bakan, 1977; Bakan, Dibb, & Reed, 1973; Coren & Porac, 1980a; Coren Searleman, & Porac, 1982; Levition & Kilty, 1976; Smart, Jeffery, & Richards, 1980)." (Coren, S. & Halpern, D.F. (1991) Left-handedness: A marker for decreased survival fitness. Psychological Bulletin 109: 98)

“Nonright-handedness (NRH) has been attributed to hypoxia-induced brain changes in the fetus and associated pregnancy and birth complications (PBCs). Maternal smoking during pregnancy is known to produce prenatal hypoxia for the fetus, which may result in low birth weight and other PBCs. It was hypothesized that maternal smoking during pregnancy results in a leftward shift of handedness in the offspring. This study compared the distribution of handedness in the offspring of mothers who did and did not smoke cigarettes during pregnancy. Information on maternal smoking, handedness, and PBCs was analyzed for 803 university students. There was a significant shift to the left in the distribution of handedness scores for the offspring of smoking mothers (N = 216), as compared to those of nonsmoking mothers (N = 587). Offspring of smoking mothers also reported significantly more PBCs. Results are consistent with the hypothesis that NRH is associated with pathological neurodevelopment.” (Bakan P (1991) Handedness and maternal smoking during pregnancy. Int J Neurosci 56 (1-4): 161)


“Using a new sample of 16 human brains (F = 8, M = 8), it was found that the splenial portion of the corpus callosum was larger and more bulbous in females than in males. In addition, the total area of the corpus callosum was both absolutely and relatively larger in females than in males, with the relative measurements (i.e., to brain weight) differing significantly. This was also true when using exponential values of brain weight commensurate with the areas and linear distances of the corpus callosum. These results, which replicate the findings of earlier work, were found by the two authors using different methods, and working independently of each other. We believe these findings provide a partial anatomical basis for purported gender differences in cognitive task behaviour, and are related to early gonadal steroidal influences during prenatal development.” (Holloway RL, de Lacoste MC (1986) Sexual dimorphism in the human corpus callosum: an extension and replication study. Hum Neurobiol 5 (2):87)

“Asymmetry of the planum temporale, a language-related intrasylvian area on the superior temporal gyrus, is the most remarkable anatomical left-right asymmetry of the human brain. The in vivo application of magnetic resonance morphometry in 52 healthy volunteers (26 dextrals and 26 sinistrals) revealed that planum temporale asymmetry is correlated with hand dominance. Left-handers had a significantly lesser degree of leftward planum temporale asymmetry than right-handers. Thus, a structural-functional relation exists in cerebral asymmetry. The correlation is likely to reflect language representation. Because familial sinistrality influenced the anatomical pattern in left-handers and planum temporale asymmetry is already present in the newborn, prenatal factors must play an important role in the development of functional laterality.” (Steinmetz H, Volkmann J, Jancke L, Freund HJ (1991) Anatomical left-right asymmetry of language-related temporal cortex is different in left- and right-handers. Ann Neurol 29 (3): 315)

“Midsagittal sections of fetal cerebra from the Yakovlev collection ranging from 26-41 weeks gestational age were photographed. The photographs were used to obtain areal measurements of the cross-sectional surface of the corpora callosa; and linear measurements of the widths of genu, body and splenium. A significant sex difference, favoring females, was found in the splenial width of the corpus callosum by 26 weeks gestational age. Although other variables, including the overall cross-sectional area of the corpus callosum, were larger in females both absolutely and relative to brain weight, the differences were not statistically significant. These results suggest that the gonadal steroids and/or genetic sex have an important role in utero in the differentiation of neural structures not associated with reproductive functions. Elaboration of sex differences, however, may occur postnatally.” (de Lacoste MC, Holloway RL, Woodward DJ (1986) Sex differences in the fetal human corpus callosum. Hum Neurobiol 5 (2): 93-6)

“One could argue, by extension, that children exposed to higher levels of testosterone in utero and during early childhood might have greater right-hemisphere capabilities, thereby earning scores within the high performance - low verbal classification of scores on the Wechsler Intelligence Scale for Children. However, it is probably not reasonable to assume a simplistic model in which testosterone secretion alone is responsible for differential hemispheric and cognitive development. A more plausible explanation lies in the influence of both androgen and estrogen upon the central nervous system (Benbow & Benbow, 1984; Christiansen, 1993; Kirkpatrick, et al., 1993)” (Kirkpatrick SW, Campbell PS, Wharry RE, MacDonald PM (1994) Performance on the Wechsler Intelligence Scale for Children as related to salivary testosterone in children with learning disabilities: a poststudy analysis. Percept Mot Skills 79(1 Pt 2):578)

"Apes when new born have very much lighter skins than adults; additional pigment becomes deposited during later development, and the same is true of the Negro. In this respect the white races are neotenous, for they retain the embryonic conditions of other forms. One of the most interesting cases of this kind is that of the hair, for Bolk has shown that a progressive series in reduction can be made out in the monkeys, apes, and man: 1. the monkey is born with a complete covering of hair; 1. the gibbon is born with the head and back covered with hair, and the other regions are covered later; 3. the gorilla is born with the head covered with hair, and the other regions are partially covered later; 4. man is born withhead covered with hair, and the other regions are scarcely covered at all later. It is noted that the lanugo, which forms a very fine covering to the unborn infant before being lost, is also present in unborn apes. Further, the lanugo is retarded in man, for he has not completely shed it by the time of birth. This series shows that the neoteny of man as regards hair is associated with a progressive retardation in the rate of its development. This retardation in the rate of development of the body, it will be remembered, is all that is required to produce the other human features mentioned above. It therefore becomes interesting to inquire whether the rate of human somatic development is really slow as compared with that of other mammals. That this actually is the case is proved by a table which was given in Chapter III (p. 22). Bolk has been able to give additional proof of this by a study of the development of teeth. In the apes the milk-teeth are cut directly after birth, the 1st molar is cut soon after the 2nd premolar, and the replacement of the milk-teeth then takes place, accompanied by the cutting of the 2nd and 3rd molars. In man, the cutting of the milk-teeth is only finished two years after birth, and this is followed by a pause until at five or six the 1st molar is cut. After this, the milk-teeth are replaced, and not until this is done does the 2nd molar appear. The 3rd molar may be cut after the 2nd, but its development is often so retarded that it is not cut at all. Indeed, retardation characterizes the development of the human dentiton as a whole. (de Beer, G. R. (1951) Embryos and Ancestors. Clarendon Press: Oxford. p. 58-9)


“Homo sapiens sapiens appeared sometime between 50,000 and 100,000 years BP, and was characterized by loss of robustness and changes in the female pelvis. The female skeletal changes are indicative of some change in pregnancy and births. These alternations may have includedd reduction in the gestation period from 11 months to the present 9 months and a concomitant increase in dependency of infants on parental care. The prediction is made on the basis of morphometric comparisons with the great apes and other mammal (Pilbeam 1984).” (Robert L. Smith (1984) Human Sperm Competition. in Sperm Competition and the Evolution of Animal Mating Systems pp. 633)

"Sperm counts were roughly stable during the interval 1930-1960, declining only thereafter (James, 1980), whereas evidence of (some) women's promiscuity considerably predates the 1960's." (James, W.H. (1989) On female primate sexual behavior. Current Anthropology 30,1: pp. 77)

"Small suggests that oestrus periods of a week or longer in female primates seem excessive if females are fertile for only 24 hours, and she notes that the human ovum is fertilizable for (an estimated mean of) about 24 hous." (James, W.H. (1989) On female primate sexual behavior. Current Anthropology 30,1: pp. 77)

"Male offspring of rats subjected to stress from days 14 to 21 of pregnancy show a persistence of female behavioral potentials and an inability to exhibit normal male copulatory patterns in adulthood. Thus the processes involved in masculinization and defiminization appear to have been compromised in the male fetuses of stresses mothers. ... On the basis of the above observations, we propose that day 18 of gestation represents a distinct and critical point in the process of sexual differentiation of the fetal rat brain." (Ward IL, Weisz J (1980) Maternal stress alters plasma testosterone in fetal males. Science 207: 328-9)

"Women exposed prenatally via their pregnant mothers to diethylstilbestrol (DES, a synthetic nonsteroidal estrogen with masculinizing effects in female mammals) received higher ratings of homosexual behavior (Ehrhardt et al., 1985) and showed an increased incidence of left-hand preference (Geschwind & Galaburda, 1985b) compared to female controls. Similarly, women with congenital adrenal hyperplasmia (CAH, an inherited condition which involves an excessive secretion of andrenal androgens) received higher ratings of homosexual behavior (Money et al., 1984; Money, 1987) and showed an increased incidence of left-hand preference (Nass et al., 1987) compared to female controls. In summary, there appears to be an association, at least in women, among excessive prenatal exposure to masculinizing hormones, homosexual behavior, and increased left-hand preference. The associations appear different for men. Among CAH men, who may have higher prenatal androgens, homosexual behavior was extremely rare (Money & Lewis, 1982, 1987; Money, 1987). Also, CAH men did not show increased left-hand preference compared to male siblings (Nass et al., 1987). Similarly, DES-exposed men showed no increase in homosexual behavior (Kester et al., 1980). In contrast, men with Klinefelter's syndrome (KS, 47XXY karyotype, a syndrome associated with reduced development of male secondary sex characteristics and possibly lower levels of prenatal androgens (Ratcliffe, 1976; Sorenson et al., 1981; Nielson et al., 1982)) showed a greater prevelance of left-hand preference than control males (Netley & Rovet, 1982; Braun, 1988). There does not appear to be a higher prevalence of homosexuality in KS men (Nielsen, 1969). However, given the lower libido of KS men (Nielsen, 1969; Raboch et al., 1979), comparisons of prevalence of atypical sexual behavior between KS men and normal men might not be appropriate. In sum, the available evidence suggests that, in contrast to women, higher exposure to masculinizing sex hormones in men is not associated with homosexual behavior and increased left-hand preference. It is open to question whether the latter two behavioral manifestations are associated with lower exposure to masculinizing hormones." (McCormick CM, Witelson SF, Kingstone E (1990) Left-handedness in homosexual men and women. Neuroendocrine implications. Psychoneuroendocrinology 15: 70-71)

"The proportion of homosexual women who showed non-CRH (22/32, 69%) was significantly greater than that of the general population (35%) (z=3.55, p=0.0005, two-tailed). If the most common definition of hand preference was considered -- hand used for writing -- the female homosexuals showed only a trend toward greater left-hand preference (6/32, 19%) than in the general population (10%) (z=1.71, p=0,09, two-tailed). The proportion of homosexual men who showed non-CRH (17/38, 45%) was not statistically different from that of the general population (35%) (z=1.20, p=0.23, two-tailed). The male homosexuals showed a similar proportion of left-hand preference based on writing hand (4/38, 11%) as in the general population (10%)." (McCormick CM, Witelson SF, Kingstone E (1990) Left-handedness in homosexual men and women. Neuroendocrine implications. Psychoneuroendocrinology 15: 72)

"T exerts its influence together with other hormones and with neurotransmitters (Hutchinson & Steimer, 1984; Whalen, 1984), and it may act on the brain as T, or by its metabolites estradiol and dihydrotestosterone." (Hassler, M. (1992) Creative musical behavior and sex hormones: musical talent and spatial ability in the two sexes. Psychoneuroendocrinology 17 (1): pp. 66)

"The critical periods, as Dorner (1988) has argued, are not completely identical but are overlapping. The assumption that androgens influence brain differentiation during the midtrimester of gestation (Dorner, 1985; 1988) has been questioned by Money (1988, p. 23), who cited the findings of Abramovich et al. (1987) who undertook an extensive neurochemical search of tissues from fetal brains, age 14-20 wk of gestation, for evidence of receptors that would take up estrogenic, androgenic, or progentinic sex hormones. The evidence was nil. Money (1988, p. 23) concluded that the stage in development what hormones influence the differentiation of the human brain as dimorphically male or female remains to be discoverd. It may be in the third trimester of pregnancy, or it may extend through the first 3 postnatal months of age. (Hassler, M. (1992) Creative musical behavior and sex hormones: musical talent and spatial ability in the two sexes. Psychoneuroendocrinology 17 (1): pp. 66-67)

"Why the left side should be especially fitted, in most people, to serve the speech output-input loop is not certain, but it seems likely that it depends on the enlargement of the planum temporale in the last quarter of fetal life, in about two out of three brains. Evidence has been found for bias towards a larger motor speech area on the left also (see Section 6.3). Somatosensory mouth areas have not been compared on two sides, to my knowledge. The main point for the RS theory is that the close proximity of the mouth and hand areas in the sensorimotor cortical strip suggests that any advantage to the left-hemisphere mouth area would be likely to give an incidental advantage to the right hand. Alternatively, if the gene works by inhibiting the growth of right-hemisphere mouth cortex, there would be an incidental inhibition of the growth of the sensorimotor cortex for the left hand. Comparisons of the cerebral hemispheres of fetal brains were made by Cunningham (1902) for evidence of superior growth of the left motor cortex in the arm area; the finds were opposite of those expected in that there was a slight advantage to the right motor cortex, which Cunningham believed was detectable in ape as well as human brains, though less marked in former. Chi, Dooing, and Gilles (1977) also found that fetal brain development was slightly faster on the right than the left side. Cunningham noted, however, that in four out of five brains belonging to the eighth month of fetal development there was an excess of growth on the left side. This asymmetry of fetal development has not been remarked upon, to my knowledge, by any more recent observer. Whether the gene works by accelerating or decelerating growth on the right or the left, some in equality is introduced, which biases the random chances of superiority on either side in favour of left-hemisphere speech and preference for the right hand." (Annett, Marian (1985) Left, Right, Hand and Brain: The Right Shift Theory London: Lawrence Erlbaum pp. 402-3)

"The observation of Barnes (1975) that left-handers were a little slower to establish regular breathing immediately after birth may be due, as she suggested, to some characteristic of the nervous system of the potential left-hander rather than that left-handedness is caused by damage consequent on cerebral hypoxia. Respiratory distress was not associated with increased incidence of sinistrality in the NDCS sample (McManus, 1981). Finally, left-handers are often found amoung those with the highest levels of achievement in the art, music, sport, and theatre (Barsley, 1966). The proposition that all these people suffered early brain damage, however minimal, seems most implausible." (Annett, Marian (1985) Left, Right, Hand and Brain: The Right Shift Theory London: Lawrence Erlbaum pp. 76)

"Recently, it was reported that breast cancer may be associated with reversed cerebral asymmetry and hand preference. (Olsson and Ingvar 1991; Sandson et al. 1992; Hsieh et al. 1992). Independently, other researchers have suggested that increased levels of estrogens in pregnancy (Trichopoulos 1990), which are associated with higher birth weight (Gerhard et al. 1987; Petridou et al. 1990; Ekbom et al. 1992), may increase the risk of breast cancer in the offspring (Trichopoulos 1990)." (Petridou, E., Flytzani, V., Youroukos, S., Lee, I.M., Yen, Y.Y., Yong, D., Trichopoulos, D. (1994) Birth weight andhandedness in boys and girls. Human Biology 66 (6): 1094)

[citations removed] "Schacter reported that women exposed in utero to the synthetic estrogen diethylstilbestrol had a handedness distribution on the Edinburgh Handedness Inventory (EHI) that was shifted away from strong right-handedness. Nass et al found that females with congenital adrenal hyperplasia (CAH), a disorder that results in increased androgen production during gestation, displayed a lesser degree of right-hand preference than unaffected sibling controls on the EHI. However, males with CAH displayed a trend in the opposite direction. More recently, Helleday et al. reported that females with CAH did not differ from controls in either degree of right-hand preference or in dichotic listening asymmetry." (Moffat, S.D. & Hampson, E. (1996) Salivary testosterone levels in left- and right-handed adults. Neuropsychologia 34 (3): pp. 225)

"Of the 39 ELBW [extremely low birth weight] children none had cerebral palsy and their average IQ at 4 years was 93. About half (54%) of the children were left-handed (-4 or -3) while of those with greater birthweights only 8% were left-handed (p=0.001) (table). The frequency of left-handedness did not differ among birthweight groups above 1000 g. Using these same tests on a separate group of 4-year-old kindergarden children of normal birthweight one of us (M. J. O'C.) found 15% left-handedness. One possible explanation for these findings is brain damage after birth. Ultrasound was not available when there children were in intensive care so we do not have direct evidence of brain damage. A 50% prevalence of left-handedness would, under the Satz hypothesis, mean that almost all the ELBW children were brain injured, all handedness being "pathological". If postnatal damage was the principal cause of the left-handedness there should have been a gradation in prevalence of left-handedness from the ELBW to the heavier infants. There was, however, no increase in left-handedness among children with birthweights 1000 and 1240g many of whomalso experienced severe neonatal difficulties. Among the main group of 115 infants a mutivariate logistic regression model showed that though a moderate or high neonatal risk score was indepentently associated with a relative risk of 4.5 for left-handedness (p=0.01), ELBW itself had an independent relative risk for left-handedness of 48 (p+0.0001). An alternative explanation is that premature delivery of ELBW infants (all were born between 26 and 29 weeks' gestation) prevents the development of normal asymmetry of the brain. Chi and co-workers have shown that differences between the temporal lobes appear at about 31 weeks' gestation. This finding, coupled with the suggestion of Geschwind and Galaburda that handedness in symmetrical brains is randomly distributed, could account for the high level of left-handedness amongst these ELBW children." (O’Callaghan EM, Tudehope DI, Dugdale AE, Mohay H, Burns Y, Cook F (1987) Handedness in children with birthweights below 1000 g. Lancet 1: 1155 (letter))

[abstract] "OBJECTIVE: To assess the neurodevelopment of adopted children who had been exposed in utero to cocaine. DESIGN: A case-control observational study. PARTICIPANTS: Twenty-three children aged 14 months to 6.5 years exposed in utero to cocaine and their adoptive mothers, and 23 age-matched control children not exposed to cocaine and their mothers, matched with the adoptive mothers for IQ and socioeconomic status. SETTING: The Motherisk Programme at The Hospital for Sick Children, Toronto, a consultation service for chemical exposure during pregnancy. MAIN OUTCOME MEASURES: Height, weight and head circumference at birth and atfollow-up, and achievement on standard tests of cognitive and language development. RESULTS: Compared with the control group, children exposed in utero to cocaine had an 8-fold increased risk for microcephaly (95% confidence interval 1.5 to 42.3); they also had a lower mean birth weight (p = 0.005) and a lower gestational age (p= 0.002). In follow-up the cocaine-exposed children caught up with the control subjects in weight and stature but not in head circumference (mean 31st percentile v. 63rd percentile) (p = 0.001). Although there were no significant differences between the two groups in global IQ, the cocaine-exposed children had significantly lower scores than the control subjects on the Reynell language test for both verbal comprehension (p = 0.003) and expressive language (p = 0.001). CONCLUSIONS: This is the first study to document that intrauterine exposure to cocaine is associated with measurable and clinically significant toxic neurologic effects, independent of postnatal home and environmental confounders. Because women who use cocaine during pregnancy almost invariably smoke cigarettes and often use alcohol, it is impossible to attribute the measured toxic effects to cocaine alone." (Nulman I, Rovet J, Altmann D, Bradley C, Einarson T, Koren G (1994) Neurodevelopment of adopted children exposed in utero to cocaine. CMAJ 151(11):1591-7 )

"From the discussion so far, the reasons for a possible elevated rate of prematurity or preterm birth in offspring of parents with anomalous dominance should be clear. The male fetus who recieves genes from the father that favor anomalous dominance may be a producer of high levels of testosterone, which may lead to premature or preterm delivery." (Geschwind & Galaburda 1987: 178, Cerebral Lateralization)

"Prematurity is more common in males and in children of DES mothers. Hyaline-membrane disease, which is more common in prematures, is strongly male predominant. Adrenal steroids play a role in this disorder, since they speed up lung maturation, but we know of no data on gonadal steroids. We have seen a masculinized female with this disorder whose mother took progesterone, which may have masculinizing effects on the fetus (Ehrdhardt and Money 1967). (Geschwind & Galaburda 1987: 179, Cerebral Lateralization)

"Based on 16 live births of bonobos in captivity, Thompson-Handler (1990) found a median gestation length of 244 days, with a range of from 227 to 277 days. Interbirth intervals at Wamba were discussed at a symposium (unpublished) in 1995 by Furuichi, who warned that more data are needed before we conclude that the shortness of the average bonobo interval (i. e., 4.5 years) distinguishes bonobos from chimpanzees. Data on wild chimpanzees may be more like those of bonobos because of the similarity in environment and food availability." (De Wall & Lanting 1997: 190, Bonobo)

"It could be the case that although growth of the left hemisphere is slowed to a greater extent in lefthanders than in righthanders, it may attain a greater final size in lefthanders. This could occur with the growth period is prolonged---for instance, when pregnancy is longer than average or when puberty is late, which would allow for further development in childhood." (Geschwind & Galaburda 1987: 98, Cerebral Lateralization)

"There is a general tendency for underweight patients to have a higher incidence of premature infants (Kaltreider 1963). (Bernds, W.P. & Barash, D.P. (1979) Early Termination of Parental Investment in Mammals, Including Humans In Evolutionary Biology and Human Social Behavior. N. Chagnon & W. Irons, eds. Pp. 503)

[from abstract]"Information was obtained on the hand preference of 88 premature and 80 matched full-term children at 7-8 years old. These children were also evaluated for neurologic status, IQ, attention-deficit hyperactivity disorder, and learning disabilities. Although the difference on hand preference was not significant, 12% more of the premature children than the full-term children were left- or mixed-handed. Results showed that, among premature children, there is an association between non-right-handedness and cognitive and behavioral deficits and that left-handed children show relative clumsiness with the non-preferred hand." (Ross G, Lipper E, Auld PA (1992) Hand preference, prematurity and developmental outcome at school age. Neuropsychologia 1992 May;30(5):483-494)

"The association between selected demographic variables and birth weight on the one hand and a composite hand preference score based on seven hand tasks (each performed twice) on the other was investigated in a sample of 1387 male and female schoolchildren aged 5 to 10 years old. In multiple regression models left-handedness was significantly more common among boys and among children of better educated mothers and tended to decrease with age. No association was found with respect to urban or rural residence or birth order. Increased birth weight was associated with right-handedness in boys but with left-handedness in girls, and the birth weight by sex interaction term was statistically significant (p = 0.037). The demographic associations in the present study are compatible with those reported previously. The different associations of birth weight with hand preference in boys and girls indicate that the pr natal hormonal factors that affect brain lateralization and handedness are qualitatively or quantitatively different in the two sexes and may be differentially associated with birth weight." (Petridou, E., Flytzani, V., Youroukos, S., Lee, I.M., Yen, Y.Y., Yong, D., Trichopoulos, D. (1994) Birth weight andhandedness in boys and girls. Human Biology 66 (6): 1093-1101)

"Recently, it was reported that breast cancer may be associated with reversed cerebral asymmetry and hand preference. (Olsson and Ingvar 1991; Sandson et al. 1992; Hsieh et al. 1992). Independently, other researchers have suggested that increased levels of estrogens in pregnancy (Trichopoulos 1990), which are associated with higher birth weight (Gerhard et al. 1987; Petridou et al. 1990; Ekbom et al. 1992), may increase the risk of breast cancer in the offspring (Trichopoulos 1990)." (Petridou, E., Flytzani, V., Youroukos, S., Lee, I.M., Yen, Y.Y., Yong, D., Trichopoulos, D. (1994) Birth weight andhandedness in boys and girls. Human Biology 66 (6): 1094)

"Barnes and Richards {12} measured the time it took for newborns to establish normal breathing, and then followed up these Ss to age three when handedness was established. They found that 29 of 30 who became right handed had established breathing in 2 min or less, whereas only 6 of 15 who became either left-handed or ambidextrous had established breating in this time. Hypoxia at birth thus seems to be a good predictor of handedness at age three." (Bakan, P. (1977) Left handedness and birth order revisted. Neuropsychologia 15 (6): 838)

"The patients were referred at ages ranging from 1 month to 5 years (Table 1). Males represented 60% of the population. Mean birthweight was 2250 g with only 42% of the infants weighing greater or equal to 2500 g. Mean birthweight of full-term infants was 2808 g. In comparison, 86% of the infants in the general population born at the hospital weighed greater or equal to 2500 g. Mean gestational age (SEM) determined by reports from referring physicians and agencies was 36.4 (0.7) weeks, with 44% representing preterm deliveries. [p.316] ... The head circumference data (Table 2) showed 34% of the subjects had head circumferences below the 5th percentile at the time of referral. Significant developmental delays were noted in all areas tested (Figure). While most of the subjects with language delays had difficulties with expressive skills, more than 11% had severe communicative disorders in which receptive as well as expressive skills were abnormal. .... Characteristic fine motor delays included failure to bring hands to the midline, to engage in midline hand play, or to exchange items from one hand to the next at the age-appropriate time. ... Detectable neurological abnormalities were seen in more than 40% of the children (Table 3)." (Davis E, Fennoy I, Laraque D, Kanem N, Brown G, Mitchell J (1992) Autism and developmental abnormalities in children with perinatal cocaine exposure. J Natl Med Assoc 84(4):315-317)

"Hypertonia was present in 30%. ... Eight (11%) of the children met DSM-III-R criteria for autism. Of these eight children, six were full-term and two were born at 32 to 34 week gestation. The mean age of their mothers at delivery was 23 1/2 years. Three mothers had histories of alcohol use on a regular basis, and one had used phencyclidine. Only one mother reported the use of heroin. ... The data in this study, showing 50% of the children at or below the 15th percentile in height and weight, would suggest that this problem may extend beyond the newborn period. ... Austistic disorder is a rare syndrome previously reported to occur in 2 to 21 per 1000 live births. To our knowledge, autism has not previously been reported in association with in utero drug exposure. [p.318] ... In addition, the drug abuse seen was clearly polydrug abuse, thus confounding the interpretation of cocaine as the responsible agent. [p.319]" (Davis E, Fennoy I, Laraque D, Kanem N, Brown G, Mitchell J (1992) Autism and developmental abnormalities in children with perinatal cocaine exposure. J Natl Med Assoc 84(4):318-19)