Maternal smoking in pregnancy and sex differences in perinatal death between boys and girls

The sex difference in perinatal mortality in developed countries is largely unexplained. The current study evaluated the differences in the impact of maternal smoking during pregnancy on the risk of perinatal death between males and females. The analysis involved 11,469 and 9,404 newborns derived from two population-based birth cohorts in Northern Finland, for 1966 and 1985-86, respectively. The perinatal mortality rate was 23 per thousand in the 1966 cohort and 9 per thousand in the 1985-86 cohort. The rate ratio (RR) for mortality for males over females is 1.15 and 1.60 in the two cohorts, respectively. Among children whose mothers smoked during pregnancy, the RR was 2.2 (95% CI 1.0, 4.7) for the former cohort and 4.8 (95% CI 1.5, 15.2) for the later cohort; and among the children whose mothers did not smoke the corresponding RR was 1.2 (95% CI 0.9, 1.6) and 1.1 (95% CI 0.6, 1.9). Maternal smoking during pregnancy could be an important determinant accounting for the excess perinatal death for males over females. Our results encourage evaluation of the findings among other populations.     

Physical fitness differences between prepubescent boys and girls

The purpose of this study was to analyze in which physical capabilities boys and girls are closer or distant. An additional objective was to find which of the body fat, physical activity, and somatotype factors have a greater effect on prepubescent children's physical fitness. This was a cross-sectional study involving 312 children (10.8 ± 0.4 years). The physical fitness assessment employed sets of aerobic fitness, strength, flexibility, speed, agility, and balance. The boys presented higher values in all selected tests, except tests of balance and flexibility, in which girls scored better. Gender differences in the physical fitness were greatest in the explosive strength of upper (p ≤ 0.01, η(p)(2) = 0.09) and lower limbs (p ≤ 0.01, η(p)(2) = 0.08), although with a medium-size effect of gender, and smaller in the abdominal (p > 0.05, η(p)(2) = 0.007) and upper limbs (p > 0.05, η(p)(2) = 0.003) muscular endurance, and trunk extensor strength and flexibility (p > 0.05, η(p)(2) = 0.001). The endomorphic (p ≤ 0.01, η(p)(2) = 0.26) in the girls, and the ectomorphic (p ≤ 0.01, η(p)(2) = 0.31) and mesomorphic (p ≤ 0.01, η(p)(2) = 0.26) in the boys, had the high-sized effect on the physical fitness. The physical activity in the girls, and the endomorphic and body fat in the boys, did not have a significant effect. These findings can help in the planning of activities that take into account the success and motivation of both boys and girls and thus increase levels of physical activity and physical fitness at school. However, in prepubescent children, one cannot neglect the influence of genetic determinism, observed from the morphoconstitutional point of view.     

Why boys will be boys and girls will be girls: Human sex development and its defects

Among the most defining events of an individual's life, is the development of a human embryo into male or a female. The phenotypic sex of an individual depends on the type of gonad that develops in the embryo, a process which itself is determined by the genetic setting of the individual. The development of the gonads is different from any other organ, as they possess the potential to differentiate into two functionally distinct organs, testes, or ovaries. Sex development can be divided into two distinctive processes, “sex determination,” which is the commitment of the undifferentiated gonad into either a testis or an ovary, a process that is genetically programmed in a critically timed manner and “sex differentiation,” which takes place through hormones produced by the gonads, once the developmental sex determination decision has been made. Disruption of any of the genes involved in either the testicular or ovarian development pathway could lead to disorders of sex development. In this review, we provide an insight into the factors important for sex determination, their antagonistic actions and whenever possible, references on the “prismatic” clinical cases are given. Birth Defects Research (Part C) 108:365–379, 2016. © 2016 Wiley Periodicals, Inc.     

Maternal smoking during pregnancy and cord blood DNA methylation: new insight on sex differences and effect modification by maternal folate levels

Maternal smoking during pregnancy may affect newborn DNA methylation (DNAm). However, little is known about how these associations vary by a newborn’s sex and/or maternal nutrition. To fill in this research gap, we investigated epigenome-wide DNAm associations with maternal smoking during pregnancy in African American mother-newborn pairs. DNAm profiling in cord (n = 379) and maternal blood (n = 300) were performed using the Illumina HumanMethylation450 BeadChip array. We identified 12 CpG sites whose DNAm levels in cord blood were associated with maternal smoking, at a false discovery rate <5%. The identified associations in the GFI1 gene were more pronounced in male newborns than in females (P = 0.002 for maternal smoking × sex interaction at cg18146737). We further observed that maternal smoking and folate level may interactively affect cord blood DNAm level at cg05575921 in the AHRR gene (P = 5.0 × 10^?4 for interaction): compared to newborns unexposed to maternal smoking and with a high maternal folate level (>19.2 nmol/L), the DNAm level was about 0.03 lower (P = 3.6 × 10^?4) in exposed newborns with a high maternal folate level, but was 0.08 lower (P = 1.2 × 10^?8) in exposed newborns with a low maternal folate level. Our data suggest that adequate maternal folate levels may partly counteract the impact of maternal smoking on DNAm. These findings may open new avenues of inquiry regarding sex differences in response to environmental insults and novel strategies to mitigate their intergenerational health effects through optimization of maternal nutrition.     

Minor differences in ADHD-related difficulties between boys and girls treated with atomoxetine for attention-deficit/hyperactivity disorder

Atomoxetine may improve ADHD-related difficulties and hence the quality of life (QoL) in children and adolescents. Perception of these difficulties may differ with the rater perspective (patient, parent, physician) or patients' sex. The objective of this study was to investigate QoL as reflected by perceived ADHD-related difficulties perceived from these three perspectives and compare boys and girls. Patients aged 6-17 with ADHD were treated with atomoxetine (target dose 0.5-1.2 mg/kg/day) in two studies. In both studies, ADHD-related difficulties were assessed after 8 and 24 weeks using the Global Impression of Perceived Difficulties (GIPD) instrument, which can be taken to reflect the patient's QoL from the three perspectives. Data from the two studies were combined and analyzed together in order to compare boys and girls. Four hundred and twenty-one patients were treated with atomoxetine, 338 boys and 83 girls. Three hundred and fifty-five patients completed the 8-week study period. QoL, as reflected by perceived ADHD-related difficulties (measured with GIPD), improved over time. Mean GIPD total scores showed a similar course over time for all rater groups, although the patients rated the degree of difficulties significantly lower than parents and physicians. The sexes did not differ significantly in mean GIPD total scores. The GIPD scores over time suggest that patients' QoL, as reflected by perceived ADHD-related difficulties, improved with time on atomoxetine. However, improvement did not differ significantly between boys and girls. Trial Registration: ClinicalTrials.gov Identifiers NCT00191516 and NCT00191737.     

Timing and genetic rapport between growth in skeletal maturity and height around puberty: similarities and differences between girls and boys.

We have analyzed longitudinal twin data by using a multivariate normal model to identify and quantify genetic effects over time on two main aspects of growth, height and skeletal maturity. The largest genetic contribution to the variance in both height and skeletal maturity coincided with the respective ages of peak growth velocity. The highest genetic covariance between these two traits coincided with the age of greatest acceleration of growth in height. These findings imply the existence of regulatory or structural genes that influence growth in both height and skeletal maturity. We also found sex differences in the rapport between velocities for height and skeletal maturity. These are consistent with a predominant role of estrogen in accelerating skeletal maturation in females, and the existence of additional mechanisms in males which may promote growth in height independently of the effects of gonadal sex steroids.     

Maternal cigarette smoking during pregnancy and offspring DNA methylation in midlife

Maternal smoking in pregnancy (MSP) has been associated with DNA methylation in specific CpG sites (CpGs) in infants and children. We investigated whether MSP, independent of own personal active smoking, was associated with midlife DNA methylation in CpGs that were previously identified in studies of MSP-DNA methylation in children. We used data on MSP collected from pregnant mothers of 89 adult women born in 1959–1964 and measured DNA methylation in blood (granulocytes) collected in 2001–2007 (mean age: 43 years). Seventeen CpGs were differentially methylated by MSP, with multiple CpGs mapping to CYP1A1, MYO1G, AHRR, and GFI1. These associations were consistent in direction with prior studies (e.g., MSP associated with more and less methylation in AHRR and CYP1A1, respectively) and, with the exception of AHRR CpGs, were not substantially altered by adjustment for active smoking. These preliminary results confirm prior prospective reports that MSP influences the offspring DNA methylation, and extends the timeframe to midlife, and suggest that these effects may persist into adulthood, independently of active smoking.     

Psychosocial factors associated with smoking and drinking among Japanese early adolescent boys and girls: Cross-sectional study

Background  

Smoking and drinking alcohol among early adolescents are serious public health concerns, but few studies have been conducted in Japan to assess their prevalence and etiology. A regional survey was conducted in eight schools in two Japanese school districts to identify psychosocial factors associated with smoking and drinking behaviors for boys and girls.     

Maternal smoking during pregnancy affects neuroendocrine cells in the neonate hamster lung

Primigravid Syrian golden hamsters were exposed in a Walton smoking machine to the smoke from either weak or strong cigarettes for 10 minute periods, 4 times a day from the 3rd to 14th (2nd last) day of pregnancy. Control hamsters were either similarly restrained in a Walton machine equipped with an unlit cigarette, or were not placed in the machine or restrained. Examination of the progeny in the first 6 days of life showed changes in density indices of grouped pulmonary neuroendocrine (NE) cells (neuroepithelial bodies, NEB) that were related to in utero exposure to maternal smoking. Argyrophil NEB were more numerous, larger, and contained more cells at birth among neonates whose mothers smoked the strong cigarette (2.45 mg nicotine and 36.8 mg tar) during pregnancy. This suggests a dose-related effect as the weak cigarette (0.37 mg nicotine and 33.8 mg tar) group did not show such changes. However, some of the changes described did not last through 3 or 6 days of age. The stress resulting from restraint alone also appeared to increase argyrophil NEB indices. Lung tissue volume fraction was increased in the weak cigarette group over all other groups at birth and 3 days; this suggests that low nicotine has the strongest pharmacological effect on lung tissue growth. The medial thickness of pulmonary arterioles was unchanged by either treatment; this provides morphometric evidence that chronic pulmonary hypertension was not present. We could not determine whether the increased NEB indices were caused by increased stainability, by activation of resident reserve cells, or by actual mitosis.     

Sex matters during adolescence: testosterone-related cortical thickness maturation differs between boys and girls

Age-related changes in cortical thickness have been observed during adolescence, including thinning in frontal and parietal cortices, and thickening in the lateral temporal lobes. Studies have shown sex differences in hormone-related brain maturation when boys and girls are age-matched, however, because girls mature 1-2 years earlier than boys, these sex differences could be confounded by pubertal maturation. To address puberty effects directly, this study assessed sex differences in testosterone-related cortical maturation by studying 85 boys and girls in a narrow age range and matched on sexual maturity. We expected that testosterone-by-sex interactions on cortical thickness would be observed in brain regions known from the animal literature to be high in androgen receptors. We found sex differences in associations between circulating testosterone and thickness in left inferior parietal lobule, middle temporal gyrus, calcarine sulcus, and right lingual gyrus, all regions known to be high in androgen receptors. Visual areas increased with testosterone in boys, but decreased in girls. All other regions were more impacted by testosterone levels in girls than boys. The regional pattern of sex-by-testosterone interactions may have implications for understanding sex differences in behavior and adolescent-onset neuropsychiatric disorders.     

Maternal smoking and twinning.

In order to investigate a possible association between maternal smoking during pregnancy and twinning, information on 1,096,330 single births and 12,342 twin births in 1983-95 was obtained from the Swedish Medical Birth Registry (MBR). All odds ratios (OR) were estimated after stratification for year of birth and maternal age, parity, and educational level. Smoking women, compared with non-smoking women, were at increased risk of having dizygotic (DZ) twins, but the risk increase was only evident among multiparas. A strong association between previous involuntary childlessness and dizygotic (DZ) twinning (especially in primiparas) was found. The strongest association between maternal smoking and DZ twinning was found among multiparas without any history of involuntary childlessness (OR: 1.35, 95%CI:1.22-1.49), whereas among women who had experienced involuntary childlessness, the opposite was seen (OR: 0.82, 95%CI:0.66-1.00, no difference between parity strata). Weinberg's differential method was used to estimate the number of monozygotic (MZ) twins, and a method of estimating stratified ORs among mothers of MZ twins was presented. No association was found between MZ twinning and maternal smoking (OR: 0.96, 95%CI:0.86-1.07), and no confounding by parity or previous involuntary childlessness was indicated. Several non-causal explanations to the positive association between DZ twinning and maternal smoking among multiparas were discussed, but homogeneity over strata indicated that maternal smoking may be a true risk factor for double ovulation.     

Relationship between plasma ammonia and blood lactate concentrations after maximal treadmill exercise in circumpubertal girls and boys

The purpose of the study was to define a relationship between plasma ammonia [NH3]pl and blood lactate concentrations [la-]b after exercise in children and to find out whether the [NH3]pl, determined during laboratory treadmill tests, may be useful as a predictor of the children's sprint running ability. A group of 20 girls and 14 boys trained in athletics or swimming and 8 untrained boys, aged 13.2 to 13.7 years, participated in the study. Their [NH3]pl and [la-]b were measured before and after incremental maximal treadmill exercise. In addition, the subjects' running performance was tested in 30-, 60- and 600- or 1000-m runs under field conditions. The [NH3]pl during the treadmill runs increased by 20.1 (SD 17.3), 24 (SD 16.7) and 10 (SD 4.3) mumol.l-1 in the girls, the trained boys and the untrained boys, respectively. The postexercise [NH3]pl correlated positively with [la-]b (r = 0.565 in the girls and 0.812 in the boys) and treadmill speed attained during the test (r = 0.489 in the girls and 0.490 in the boys). Significant correlations were also found between [NH3]pl obtained during the treadmill test and the times of 30- and 60-m runs (r = -0.676 and -0.648, respectively) in the boys but not in the girls. A comparison of the present data with those reported previously in adults showed that increases in [NH3]pl during maximal exercise in children would seem to be lower than in adult subjects both in absolute values and in relation to [la-]b.(ABSTRACT TRUNCATED AT 250 WORDS)     

Longitudinal study on growth in height in Polish boys and girls

Physical growth and development of children, determined by endogenous factors (genetic and paragenetic) is modified by numerous exogenic ones. This affects differentiation of ways of growth in individual children. In order to estimate the individual growth patterns and changes in growth rate as well as differences in growth of boys and girls, one must observe the process of growth of the same children and over a period of many years (longitudinal study). Such longitudinal study is the only way to provide information about the variability of growth and growth velocity at each age.     

Bioactivity of luteinizing hormone during normal puberty in girls and boys

In order to evaluate the in vitro bioactivity of LH during normal puberty compared to LH immunoactivity measured in a highly sensitive immunoassay, blood plasma samples from healthy children were analyzed in a mouse Leydig cell assay (MLCA). Blood samples were obtained from 60 healthy girls and boys during normal pubertal development. Samples were taken on two occasions with a 1-year interval. Three daytime samples and three nighttime samples were analyzed. The correlation of the LH immunoradiometric assay (IRMA) activity with the LH activity in the MLCA varied from 0.60 to 0.96 in the different pubertal stages. During pubertal development, a gradually increase in the activity of LH in both the IRMA and MLCA was found. The ratio of the in vitro bioactivity compared to the immunoreactivity (B/I ratio) did not change significantly during puberty: it was 0.84 (SD 0.58) and 0.66 (SD 0.40) during the first and second sampling period in girls and 0.88 (SD 0.38) and 0.91 (SD 0.46, NS) in the boys. The B/I ratio of LH does not change during puberty. With a high sensitivity and specificity, measurement of LH by IRMA gives representative measurements of the LH in vitro bioactivity in children during pubertal development. Copyrightz1999S. KargerAG,Basel