Early Physical Maturation Research Articles

Predicting the Timing of First Sexual Intercourse for At-Risk Adolescent Males

Event history analysis was used to test a developmental model of the timing of first sexual intercourse in the Oregon Youth Study sample of adolescent males at risk for delinquency. The event history models spanned grades 7-12 with yearly multimethod, multiagent measures. A 3-step mediational model of predictors was tested, including contextual and process factors and boys' characteristics. Predictors included one-time measures of socioeconomic status, parental antisocial behavior, and time-varying measures of parental transitions, parental monitoring, deviant peer association, and the boys' antisocial/delinquent behavior, substance use, physical maturation, academic achievement, and anxiety. As predicted, antisocial/delinquent behavior and substance use along with early physical maturity and parental transitions predicted early onset of sexual intercourse. Anxiety was related to delay of first intercourse. Results and intervention implications are discussed in terms of the developmental findings.

Does early physical maturity influence breast cancer risk?

Earlier onset of menarche and tallness in adult women are mainly confirmed as risk markers for breast cancer. Recent disparate case-control studies have reported abdominal-type obesity and higher circulating levels of insulin, testosterone and insulin-like growth factor 1, to be further risk markers for breast cancer. There is evidence that abdominal-type obesity is recognisable in girls even before puberty, and disparate studies have shown it to be correlated with earlier onset of menarche, insulin resistance leading to hyperinsulinaemia, and an abnormal sex steroid profile. The implications are that earlier onset of puberty in a subset of girls can lead to more prolonged exposure of developing breast tissue to an abnormal sex steroid profile and also to a higher circulating level of insulin. It is postulated that these metabolic/endocrine concomitants of abdominal-type obesity could play a role in promoting mammary carcinogenesis at a young age, particularly if genetic predisposition is present.

New developments in adolescent health care

Shakespeare’s description of youth is scarcely less precise a definition of adolescence than those in vogue today. A critical period of biologic, psychological, and social changes, adolescence is more a stage than an age, during which the child struggles through the complex transition to adulthood.‘~2 Earlier physical maturation, increasing complexity of the industrialized world, diminishing social assistance, and increased mobility of the family, regardless of socioeconomic and demographic factors, have made adolescence a particularly vulnerable period today.3 Most children weather the transition to adulthood relatively well and manifest a positive self-image, good impulse control, and healthy acceptance of the anatomic and physiologic changes of adolescence.4 In addition, most adolescents are healthy and few suffer from a health-related limitation of activity.5* 6 However, this generally healthy status is being steadily eroded by illness and injury associated with substance abuse, sexual activity, and violence.

Perceived Maturity as a Function of Appearance Cues in Early Adolescence: Ratings by Unacquainted Adults, Parents, and Teachers

Two related studies addressed the extent to which appearance cues affect perceptions of early adolescents' physical maturity, age, and social maturity and the degree to which perceptions of unacquainted adults and perceptions of parents and teachers correspond. Photographic slides of 6th through 9th graders were rated by unacquainted adults on 7-point rating scales of physical maturity, age, and attractiveness. Physical appearance cues were potent elicitors of age perceptions. Subsamples of these adolescents were rated by their parents and teachers on physical and social maturity. Parents', and to a lesser extent teachers', physical-maturity ratings contributed significant portions of the variance in their social-maturity ratings of the target adolescents. Unacquainted adults' ratings of attractiveness significantly correlated with their ratings of boys' physical maturity but not with the physical-maturity ratings of boys or girls by parents or teachers. Fathers' social-maturity ratings and independent attractiveness ratings of their daughters showed moderate correlations.

Contraceptive Knowledge, Attitudes and Behaviors of Black Adolescent Males Attending a Predominately Black University

A survey of 107 Black male college students attending Howard University Washington D.C. on knowledge attitudes and practices regarding contraception revealed early age of 1st sexual intercourse incomplete contraceptive education and a variable degree of male responsibility. The survey was conducted in freshmen and sophomore general health classes using 51 multiple choice and open-ended questions. The subjects mean age was 18.3 and age at 1st intercourse 12.0 (mean 11.3 for freshmen 12.2 for sophomores and 13.3 for students classified by grade). Contraceptives currently being used were condom by 41.1% withdrawal by 19.6% pill by 17.8% rhythm by 2.8% douche by 1.9% and IUD by 0.9%. 11.9% used no method. When asked to rate 6 methods for effectiveness 37% chose pills as most effective 24% chose condoms 8.4% chose diaphragms and 4.7% chose rhythm. 62% overall believed that contraception is a shared responsibility with percentages rising with age. In open-ended questions many students expressed the feeling that their attitudes affected their practice more than any contraception education. Some said they were using because they were too young to be a father others that the woman insisted. Among the reasons cited for why they were using were: It did enter my mind; It should be spontaneous; not enough time; it reduces sexual pleasure; and lack of knowledge. The study suggested that early physical maturation had surpassed the young mens education and sense of responsibility.

Third molar impaction--a consequence of late M3 mineralization and early physical maturity.

The purpose of the present investigation was to analyse the influence of late M3 mineralization and early physical maturity on normal eruption of upper and lower M3s in both sexes The cases investigated were selected from a larger study of craniofacial growth (Bjork, 1968). It was made a condition, that longitudinal complete yearly records should be available from before puberty until 25 years of age, and all first and second molars should be present throughout the period of investigation. 91 subjects (36 girls and 55 boys) were included in the study. About 75 per cent of them had undergone some kind of orthodontic treatment with or without premolar extractions. A total of 314 M3s were classified in 3 subgroups: Normal Eruption (NE), Vertical Impaction (VI) and Horizontal Impaction (HI), according to their status at the age of 25 years. The age at M3 mineralization stage E (Demirjian et al ., 1973) was determined from the orthopantomograms. Physical maturity was recorded as the age of union of the distal epiphysis in Radius (Ru), as seen on the hand-wrist radiographs. The subgroups VI and HI displayed significantly delayed ages of mineralization of M3 compared to the NE subgroups. The largest and most significant differences were seen in girls. When M3 mineralization age was related to physical maturity, the differences between the NE subgroups and the VI/HI subgroups were accentuated in general. The investigation led to the following conclusions: Late M3 mineralization in combination with early physical maturity is an important aetiological factor in the impaction of M3, where unfavourable space conditions could be the precipitating factor. Clinically, the prediction of the risk of impaction can be improved by taking this into account.

Rate of physical maturation and handedness

Early versus late physical maturation was measured in 713 females and 467 males using the onset of secondary sexual characteristics, age of menarche, and relative body size. Delayed rates of maturation were associated with an increased incidence of left‐handedness in both sexes.

Physical and reproductive characteristics of an expanding woodland caribou population (Rangifer tarandus caribou) in northern Labrador

One hundred and fifty-nine caribou (Rangifer tarandus caribou) were collected from the area of precalving distribution of the George River population in northern Labrador between April 3 and 15, 1980. The sample revealed that caribou of northern Labrador reach physical and reproductive maturity earlier than most other free-ranging caribou populations in North America. Females attained mature values for lean body weight and shoulder height by 34 months and for total body length, heart girth, and mandible length by 46 months. Pregnancy rates for females 22, 34, and 46 months and older were 43, 90, and 95%, respectively. Measurements of fat reserves showed George River females to be in superior physical condition during spring migration than caribou on mainland Northwest Territories. Fat reserves, however, were substantially less than comparable values for females collected from the same population in March, 1976. The calf: pregnant female ratio was 42:100, suggesting a 1st year rate of mortality of approximately 58%. The most common internal parasites were Cysticercus tenuicollis and Fascioloides magna. It is concluded that the recent growth of the George River population has resulted from early female physical and reproductive maturity, low adult mortality, and high survival of calves.

Menarcheal age in girls with congenital dislocation of the hip.

The age at menarche was recorded in a series of girls with congenital dislocation of the hip and compared with a control sample drawn from the population at risk. The menarcheal age of the CDH patients was decreased by, on average, six months, the decrease being caused by the presence among the CDH girls of a few individuals with a very early menarche. These girls were heavier and taller than other CDH girls, who in their turn, are taller and heavier than other girls. The findings support the concept of CDH as a manifestation of some hormonal deviation, which also causes early physical maturation.