Harriet L. Miles

Defects in imprinting and genome-wide DNA methylation are not common in the in vitro fertilization population

OBJECTIVE To examine an IVF cohort for imprinted and genome-wide DNA methylation abnormalities. DESIGN Retrospective study. SETTING Research laboratory. PATIENT(S) DNA samples from a previously described IVF cohort that comprised 66 IVF-conceived prepubertal children (IVF, n = 34; intracytoplasmic sperm injection, n = 32) and 69 matched naturally conceived controls. INTERVENTION(S) DNA methylation was examined at four imprinted gene loci (H19, SNRPN, KCNQ1OT1, and IGF2) and satellite 2 using methylation-sensitive quantitative polymerase chain reaction (MSQ-PCR) followed by bisulfite sequencing at H19, SNRPN, and KCNQ1OT1. Methylated DNA immunoprecipitation (MeDIP) microarray with validation using the Sequenom MassARRAY EpiTYPER(®) platform was also used. MAIN OUTCOME MEASURE(S) Percentage of DNA methylation by MSQ-PCR, differential methylation based on microarray signal intensity, and percentage DNA methylation as determined by Sequenom MassARRAY EpiTYPER were compared. RESULT(S) No differences in percentage of methylation between the IVF and control group were observed at H19, KCNQ1OT1, SNRPN, or IGF2. Absence of aberrant imprinting was confirmed using bisulfite sequencing. Methylation of satellite 2 repeats (a surrogate for global methylation) showed no difference between the IVF and control groups. MeDIP was used to screen for differences in promoter methylation. Subsequent quantification of methylation of eight candidate genes using the Sequenom MassARRAY EpiTYPER system did not reveal any differential methylation. CONCLUSION(S) Low-level imprinting errors are not common in the IVF population.

Fetal origins of adult disease: a paediatric perspective.

Prepubertal children born SGA or VLBW premature exhibit marked insulin resistance. There are similarities between SGA and VLBW children in that both are exposed to sub-optimal environments that encompass undernutrition and/or malnutrition during the equivalent of the last trimester of pregnancy. Although both SGA and VLBW groups fail to reach genetic height potential and are recognized causes of short stature in childhood, there are differences between the groups with respect to the growth hormone and IGF-I axis.SGA children have elevated IGFI levels, possibly due to either hyperinsulinism or partial IGF-I resistance, whereas VLBW children have low IGF-I and IGFBP-3 levels suggestive of GH resistance. Thus the nature and timing of the early insult may lead to discordant changes to the metabolic and endocrine axes.IVF children are taller with increased IGF I, IGF II and IGFBP3 expression. These changes could be due to alterations in the environment of the periconceptual embryo resulting in changes in imprinting of genes involved in growth and development. The phenotypic, endocrine and metabolic consequences of alterations in the periconceptual, fetal and early neonatal periods is an area of intense investigation. Future research in this field is likely to focus on the mechanisms through which environmental changes lead to these programmed effects.

Increasing Maternal Age Is Associated with Taller Stature and Reduced Abdominal Fat in Their Children

Background Maternal age at childbirth continues to increase worldwide. We aimed to assess whether increasing maternal age is associated with changes in childhood height, body composition, and metabolism. Methods 277 healthy pre-pubertal children, born 37–41 weeks gestation were studied. Assessments included: height and weight corrected for parental measurements, DEXA-derived body composition, fasting lipids, glucose, insulin, and hormonal profiles. Subjects were separated according to maternal age at childbirth: <30, 30–35, and >35 years. Results Our cohort consisted of 126 girls and 151 boys, aged 7.4±2.2 years (range 3–10); maternal age at childbirth was 33.3±4.7 years (range 19–44). Children of mothers aged >35 and 30–35 years at childbirth were taller than children of mothers aged <30 years by 0.26 (p = 0.002) and 0.23 (p = 0.042) SDS, respectively. There was a reduction in childhood BMISDS with increasing maternal age at childbirth, and children of mothers aged >35 years at childbirth were 0.61 SDS slimmer than those of mothers <30 years (p = 0.049). Children of mothers aged 30–35 (p = 0.022) and >35 (p = 0.036) years at childbirth had abdominal adiposity reduced by 10% and 13%, respectively, compared to those in the <30 group. Children of mothers aged 30–35 years at childbirth displayed a 19% increase in IGF-I concentrations compared to offspring in <30 group (p = 0.042). Conversely, IGF-II concentrations were lower among the children born to mothers aged 30–35 (6.5%; p = 0.004) and >35 (8.1%; p = 0.005) compared to those of mothers aged <30 years. Girls of mothers aged 30–35 years at childbirth also displayed improved HOMA-IR insulin sensitivity (p = 0.010) compared to girls born to mothers aged <30 years. Conclusions Increasing maternal age at childbirth is associated with a more favourable phenotype (taller stature and reduced abdominal fat) in their children, as well as improved insulin sensitivity in girls.

Ovarian stimulation leads to shorter stature in childhood

BACKGROUND We aimed to determine whether children conceived with ovarian stimulation alone (OS(A)) would differ phenotypically and biochemically from naturally conceived children of fertile and subfertile parents. METHODS Healthy pre-pubertal children aged 3-10 years, born at term, after singleton pregnancies were recruited in Auckland (New Zealand) and were allocated into three groups: (i) children conceived following OS(A) and naturally conceived children of (ii) subfertile and (iii) fertile parents. Anthropometric, endocrine and metabolic parameters were recorded. Childrens heights and body mass index (BMI) were expressed as standard deviation scores (SDS) and corrected for genetic potential (i.e. parental height or BMI). RESULTS Three hundred fifty-two children were studied: 84 OS(A) subjects and 268 naturally conceived controls consisting of 54 children of subfertile parents and 214 children of fertile parents. Children of subfertile and fertile parents did not differ in measured outcomes. Overall, OS(A) children were shorter than children of both subfertile (SDS: -0.08 ± 0.09 versus 0.32 ± 0.07; P= 0.001) and fertile (SDS: -0.08 ± 0.09 versus 0.45 ± 0.10; P= 0.004) parents when corrected for genetic height potential. OS(A) boys were shorter than boys of subfertile (SDS:-0.18 ± 0.14 versus 0.42 ± 0.16; P= 0.03) and fertile (SDS: -0.18 ± 0.14 versus 0.35 ± 0.08; P= 0.01) parents. There was also a trend towards OS(A) girls being shorter than girls of subfertile parents (P= 0.06), but not significantly shorter than those of fertile parents (P= 0.17). OS(A) children also had a lower corrected BMISDS than children of subfertile (SDS-0.90 ± 0.15 versus -0.37 ± 0.17; P= 0.06) and fertile (-0.90 ± 0.15 versus -0.34 ± 0.10; P= 0.008) parents. Among metabolic parameters, fasting glucose was lower in OS(A) children than that in children of fertile parents (4.62 ± 0.07 versus 4.81 ± 0.04; P= 0.006). CONCLUSIONS Conception after OS(A) was associated with shorter stature, particularly in boys, compared with naturally conceived children of fertile and subfertile parents.

Birth order progressively affects childhood height

There is evidence suggesting that first‐born children and adults are anthropometrically different to later‐borns. Thus, we aimed to assess whether birth order was associated with changes in growth and metabolism in childhood.

Increasing paternal age at childbirth is associated with taller stature and less favourable lipid profiles in their children

Paternal age at childbirth has been increasing worldwide, and we assessed whether this increase affects growth, body composition and metabolism in their children.

Enhanced Insulin Sensitivity in Prepubertal Children with Constitutional Delay of Growth and Development

OBJECTIVE To test the hypothesis that prepubertal children with presumed constitutional delay of growth and development (CDGD) have enhanced insulin sensitivity and, therefore, insulin sensitivity is associated with later onset of puberty. STUDY DESIGN Twenty-one prepubertal children with presumed CDGD and 23 prepubertal control children, underwent a frequently sampled intravenous glucose tolerance test to evaluate insulin sensitivity and other markers of insulin, glucose, and growth regulation. RESULTS Children in the CDGD group were shorter and leaner than control subjects. Children with presumed CDGD were 40% more insulin sensitive (17.0 x 10(-4) min(-1)/[mU/L] versus 12.1 x 10(-4) min(-1)/[mU/L]; P = .0006) and had reduced acute insulin response, thus maintaining euglycemia (216 mU/L versus 330 mU/L; P = .02) compared with control subjects. In addition, the CDGD group had lower serum insulin-like growth factor binding protein 3 levels (3333 ng/mL versus 3775 ng/mL; P = .0004) and a trend toward lower serum insulin-like growth factor-II levels (794 ng/mL versus 911 ng/mL; P = .06). CONCLUSION Prepubertal children with presumed CDGD have enhanced insulin sensitivity, supporting the hypothesis that insulin sensitivity is associated with timing of puberty. It may signify long-term biological advantages with lower risk of metabolic syndrome and malignancy.

The phenotype of an IVF child is associated with peri-conception measures of follicular characteristics and embryo quality

STUDY QUESTION Are childhood measures of phenotype associated with peri-conception parental, IVF treatment and/or embryonic characteristics of IVF children? SUMMARY ANSWER Birthweight, childhood body mass index (BMI) and height of pre-pubertal IVF children were strongly associated with peri-conception factors, including follicular and embryonic characteristics. WHAT IS KNOWN ALREADY A growing number of studies have identified a range of phenotypic differences between IVF and naturally conceived pre-pubertal children; for example, birthweights are lower following a fresh compared with a thawed embryo transfer. STUDY DESIGN, SIZE, DURATION This retrospective cohort study included IVF children (n = 96) born at term (>37 weeks) after a singleton pregnancy from the transfer of either fresh or thawed embryos in New Zealand. Between March 2004 and November 2008, these children were subjected to clinical assessment before puberty. PARTICIPANTS/MATERIALS, SETTING, METHODS Clinical assessment provided anthropometric measures of children aged 3.5-11 years old. Peri-conception factors (n = 36) derived retrospectively from parental, treatment, laboratory and embryonic variables (n = 69) were analysed using multiple stepwise regression with respect to standard deviation scores (SDSs) of the birthweight, mid-parental corrected BMI and height of the IVF children. Data from children conceived from fresh (n = 60) or thawed (n = 36) embryos, that met inclusion criteria and had high-quality data with >90% completeness, were analysed. MAIN RESULTS AND THE ROLE OF CHANCE Embryo treatment at transfer was identified as a predictor of birthweight with thawed embryos resulting in heavier birthweights than fresh embryos [P = 0.02, 95% confidence interval (CI) fresh minus thawed: -1.047 to -0.006]. Birthweight SDS was positively associated with mid-parental corrected BMI SDS (P = 0.003, slope 0.339 ± 0.100). Four factors were related (P < 0.05) to mid-parental corrected height SDS. In particular, child height was inversely associated with the diameter of lead follicles at oocyte retrieval (P < 0.0001, slope -0.144 ± 0.040) and with the quality score of embryos at transfer (P = 0.0008, slope -0.425 ± 0.157), and directly associated with the number of follicles retrieved (P = 0.05, slope 1.011 ± 0.497). Child height was also positively associated with the transfer of a fresh as opposed to thawed embryo (P < 0.001, 95% CI 0.275-0.750). LIMITATIONS, REASONS FOR CAUTION More than one embryo was transferred in most cycles so mean development and quality data were used. The large number of variables measured was on a relatively small sample size. Large cohorts from multiple clinics using a variety of treatment protocols and embryology methods are needed to confirm the associations identified and ultimately to test these factors as possible predictors of phenotype. WIDER IMPLICATIONS OF THE FINDINGS This is the first study to directly associate peri-conception measures of IVF treatment with a pre-pubertal childs phenotype. Demonstration that peri-conception measures relate to a pre-pubertal childs phenotype extends the range of factors that may influence growth and development. These findings, if corroborated by larger studies, would provide invaluable information for practitioners, who may want to consider the impact of ovarian stimulation protocols as well as the quality of the embryo transferred on a childs growth and development, in addition to their impact on pregnancy rate. STUDY FUNDING/COMPETING INTERESTS This work was supported by grants from the National Research Centre of Growth and Development New Zealand (grant 3682065) and the Australasian Paediatric Endocrine Group (APEG; grant 3621994), as well as a fellowship from Fertility Associates New Zealand awarded to M.P.G. In terms of competing interest, J.C.P is a shareholder of Fertility Associates. M.P.G. currently holds the position of Merck Serono Lecturer in Reproductive Biology. W.S.C. and P.L.H. have also received grants and non-financial support from Novo Nordisk, as well as personal fees from Pfizer that are unrelated to the current study. The other authors have no conflict of interest to declare.