Maternal insulin-like growth factor-I levels (IGF-I) reflect placental mass and neonatal fat mass

Association between excessive fetal growth and maternal cancer in Shanghai, China: a large, population-based cohort study

The prevalence of high birth weight or large for gestational age (LGA) infants is increasing, with increasing evidence of pregnancy-related factors that may have long-term impacts on the health of the mother and baby. We aimed to determine the association between excessive fetal growth, specifically LGA and macrosomia, and subsequent maternal cancer by performing a prospective population-based cohort study. The data set was based on the Shanghai Birth Registry and Shanghai Cancer Registry, with medical records from the Shanghai Health Information Network as a supplement. Macrosomia and LGA prevalence was higher in women who developed cancer than in women who did not. Having an LGA child in the first delivery was associated with a subsequently increased risk of maternal cancer (hazard ratio [HR] = 1.08, 95% confidence interval [CI] 1.04-1.11). Additionally, in the last and heaviest deliveries, there were similar associations between LGA births and maternal cancer rates (HR = 1.08, 95% CI 1.04-1.12; HR = 1.08, 95% CI 1.05-1.12, respectively). Furthermore, a substantially increased trend in the risk of maternal cancer was associated with birth weights exceeding 2500 g. Our study supports the association between LGA births and increased risks of maternal cancer, but this risk requires further investigation.

Comparative Proteomic Assessment of Normal vs. Polyhydramnios Amniotic Fluid Based on Computational Analysis

Mass spectrometry-based proteomics have become a valued tool for conducting comprehensive analyses in amniotic fluid samples with pathologies. Our research interest is the finding and characterization of proteins related to normal vs. polyhydramnios (non-immune hydrops) pregnancy. Proteomic analysis was performed on proteins isolated from fresh amniotic fluid samples. Proteins were fractionated by 2DE using a different pI range (pI 3–11, pI 4–7) and analyzed with MALDI-TOF-MS. Furthermore, by using computational analysis, identified proteins in protein maps specific to normal vs. polyhydramnios pregnancy were compared and the quantities of expressed proteins were evaluated mathematically. Comparative analysis of proteome characteristic for the same polyhydramnios pregnancy fractionated by 2DE in different pI range (3–11 and 4–7) was performed and particular protein groups were evaluated for the quantification of changes within the same protein level. Proteins of normal and polyhydramnios pregnancies were fractionated by 2DE in pI range 3–11 and in pI range 4–7. Mass spectrometry analysis of proteins has revealed that the quantity changes of the main identified proteins in normal vs. polyhydramnios pregnancy could be assigned to immune response and inflammation proteins, cellular signaling and regulation proteins, metabolic proteins, etc. Specifically, we have identified and characterized proteins associated with heart function and circulatory system and proteins associated with abnormalities in prenatal medicine. The following are: serotransferrin, prothrombin, haptoglobin, transthyretin, alpha-1-antitrypsin, zinc-alpha-2-glycprotein, haptoglobin kininogen-1, hemopexin, clusterin, lumican, afamin, gelsolin. By using computational analysis, we demonstrated that some of these proteins increased a few times in pathological pregnancy. Computer assistance analysis of 2DE images suggested that, for the better isolation of the proteins’ isoforms, those levels increased/decreased in normal vs. polyhydramnios pregnancy, and the fractionation of proteins in pI rage 3–11 and 4–7 could be substantial. We analyzed and identified by MS proteins specific for normal and polyhydramnios pregnancies. Identified protein levels increased and/or modification changed in case of non-immune hydrops fetus and in cases of cardiovascular, anemia, growth restriction, and metabolic disorders. Computational analysis for proteomic characterization empower to estimate the quantitative changes of proteins specific for normal vs. polyhydramnios pregnancies.

Physiological changes in pregnancy and their influence on the endocrine investigation

BACKGROUND

Physiological changes in pregnancy may result in significant alterations in endocrine hormone profiles, serum and urine electrolytes and endocrine gland morphology on imaging. Pregnancy-specific pathophysiological processes may also affect the results for endocrine tests. Investigation of endocrine disorders in pregnancy requires knowledge of these changes and awareness of the safety of dynamic hormone testing and imaging for the mother and foetus.

OBJECTIVE

This review seeks to outline the important physiological changes in pregnancy affecting reference intervals of basal and dynamic endocrine tests in pregnancy and the scenarios in which these changes are clinically significant, the pregnancy-specific disorders that may affect the investigation of endocrine disorders, and the safety of dynamic testing and imaging.

CONCLUSION

Awareness of the effect of physiological changes, and the potential impact of pregnancy-specific disorders of endocrine tests, and the safety of imaging is crucial to the management of endocrine disorders in pregnancy.

Novel roles of mechanistic target of rapamycin signaling in regulating fetal growth†

Mechanistic target of rapamycin (mTOR) signaling functions as a central regulator of cellular metabolism, growth, and survival in response to hormones, growth factors, nutrients, energy, and stress signals. Mechanistic TOR is therefore critical for the growth of most fetal organs, and global mTOR deletion is embryonic lethal. This review discusses emerging evidence suggesting that mTOR signaling also has a role as a critical hub in the overall homeostatic control of fetal growth, adjusting the fetal growth trajectory according to the ability of the maternal supply line to support fetal growth. In the fetus, liver mTOR governs the secretion and phosphorylation of insulin-like growth factor binding protein 1 (IGFBP-1) thereby controlling the bioavailability of insulin-like growth factors (IGF-I and IGF-II), which function as important growth hormones during fetal life. In the placenta, mTOR responds to a large number of growth-related signals, including amino acids, glucose, oxygen, folate, and growth factors, to regulate trophoblast mitochondrial respiration, nutrient transport, and protein synthesis, thereby influencing fetal growth. In the maternal compartment, mTOR is an integral part of a decidual nutrient sensor which links oxygen and nutrient availability to the phosphorylation of IGFBP-1 with preferential effects on the bioavailability of IGF-I in the maternal-fetal interface and in the maternal circulation. These new roles of mTOR signaling in the regulation fetal growth will help us better understand the molecular underpinnings of abnormal fetal growth, such as intrauterine growth restriction and fetal overgrowth, and may represent novel avenues for diagnostics and intervention in important pregnancy complications.

Complex, coordinated and highly regulated changes in placental signaling and nutrient transport capacity in IUGR

The most common cause of intrauterine growth restriction (IUGR) in the developed world is placental insufficiency, a concept often used synonymously with reduced utero-placental and umbilical blood flows. However, placental insufficiency and IUGR are associated with complex, coordinated and highly regulated changes in placental signaling and nutrient transport including inhibition of insulin and mTOR signaling and down-regulation of specific amino acid transporters, Na⁺/K⁺-ATPase, the Na^+/H⁺-exchanger, folate and lactate transporters. In contrast, placental glucose transport capacity is unaltered and Ca²⁺-ATPase activity and the expression of proteins involved in placental lipid transport are increased in IUGR. These findings are not entirely consistent with the traditional view that the placenta is dysfunctional in IUGR, but rather suggest that the placenta adapts to reduce fetal growth in response to an inability of the mother to allocate resources to the fetus. This new model has implications for the understanding of the mechanisms underpinning IUGR and for the development of intervention strategies.

Human placental glucose transport in fetoplacental growth and metabolism

While efficient glucose transport is essential for all cells, in the case of the human placenta, glucose transport requirements are two-fold; provision of glucose for the growing fetus in addition to the supply of glucose required the changing metabolic needs of the placenta itself. The rapidly evolving environment of placental cells over gestation has significant consequences for the development of glucose transport systems. The two-fold transport requirement of the placenta means also that changes in expression will have effects not only for the placenta but also for fetal growth and metabolism. This review will examine the localization, function and evolution of placental glucose transport systems as they are altered with fetal development and the transport and metabolic changes observed in pregnancy pathologies.

Changes in biochemical tests in pregnancy and their clinical significance

Interpretation of laboratory investigations relies on reference intervals. Physiological changes in pregnancy may result in significant changes in normal values for many biochemical assays, and as such results may be misinterpreted as abnormal or mask a pathological state. The aims of this review are as follows: 1. To review the major physiological changes in biochemical tests in normal pregnancy. 2. To outline where these physiological changes are important in interpreting laboratory investigations in pregnancy. 3. To document the most common causes of abnormalities in biochemical tests in pregnancy, as well as important pregnancy-specific causes.

Influence of aerobic exercise on maternal lipid levels and offspring morphometrics

BACKGROUND

Maternal BMI, lipid levels (cholesterol, triglyceride, LDL, HDL), and exercise amount are interrelated and each influence offspring body size. This study proposed to determine the influence of exercise on maternal lipid levels and infant body size.

METHODS

We had 36 participants complete these measures. Participants in the aerobic exercise intervention (n = 14) completed three 50-min sessions weekly from 16 weeks gestation to delivery and were compared with a non-exercise control group (n = 22). Maternal lipid profiles were assessed at 16 and at 36 weeks gestation. Fetal body size was measured at 36 weeks gestational age using ultrasound assessment. Neonatal body size measures were acquired from birth records. Statistical analysis included two-sample t-tests, correlations, and regression models.

RESULTS

Participants were similar in age, pre-pregnancy BMI, gravida, parity, education, and gestational weight gain (GWG). There were no differences in gestational age, Apgar scores at 1 and 5 min for infants of exercisers relative to controls. Exercisers had higher pre-training triglycerides (p = 0.004) and pregnancy change in triglycerides (p = 0.049) compared to controls. Head circumference was significantly larger in exercise exposed infants relative to infants of controls. Pregnancy METs had a positive relationship with birth length (r = .445, p = .006) and birth weight (r = .391, p = .02). GWG had a moderate, positive relationship with fetal abdominal circumference (r = .570, p = .004). Regression analysis indicated 5 predictors explained 61.7% of the variance in birth weight (Adj.R² = 0.469, F(5,13) = 5,13, p = 0.02); it was found that pregnancy METs (β = .724, p = .007), 36 week cholesterol (β = 1.066, p = .02), and 36 week LDL (β = -1.267, p = .006) significantly predict birth weight. Regression analysis indicated 4 predictors explained 43.8% of the variance in birth length (Adj.R² = 0.306, F(4,17) = 3.32, p = 0.04); it was found that pregnancy METs (β = .530, p = .03), and 36 week LDL (β = -.891, p = .049) significantly predict birth length.

CONCLUSION

The primary association and predictors of infant body size was related to pregnancy exercise and late pregnancy cholesterol and LDL levels. Considering these relationships, it is essential that women maintain aerobic exercise during pregnancy, but should also be cognizant of lipid levels during their pregnancy. Therefore intervention during pregnancy focused on infant body size should involve exercise and and quality nutritional intake foods during pregnancy.

Maternal breast cancer risk in relation to birthweight and gestation of her offspring

BACKGROUND

Parity and age at first pregnancy are well-established risk factors for breast cancer, but the effects of other characteristics of pregnancies are uncertain and the literature is inconsistent.

METHODS

In a cohort of 83,451 parous women from the general population of the UK, which collected detailed information on each pregnancy and a wide range of potential confounders, we investigated the associations of length of gestation and birthweight of offspring in a woman's pregnancies with her breast cancer risk, adjusting for a full range of non-reproductive as well as reproductive risk factors unlike in previous large studies.

RESULTS

Gestation of the first-born offspring was significantly inversely related to the risk of pre-menopausal breast cancer (p trend = 0.03; hazard ratio (HR) for 26-31 compared with 40-41 weeks, the baseline group, = 2.38, 95% confidence interval (CI) 1.26-4.49), and was borderline significantly related to risk of breast cancer overall (p trend = 0.05). Risk was significantly raised in mothers of high birthweight first-born (HR for breast cancer overall = 1.53, 95% CI 1.06-2.21 for ≥ 4500 g compared with 3000-3499 g, the baseline group). For gestation and birthweight of most recent birth, there were no clear effects. Analyses without adjustment for confounders (other than age) gave similar results.

CONCLUSIONS

Our data add to evidence that short gestation pregnancies may increase the risk of breast cancer, at least pre-menopausally, perhaps by hormonal stimulation and breast proliferation early in pregnancy without the opportunity for the differentiation that occurs in late pregnancy. High birthweight first pregnancies may increase breast cancer risk, possibly through the association of birthweight with oestrogen and insulin-like growth factor 1 levels.

MANAGEMENT OF ENDOCRINE DISEASE: Acromegaly and pregnancy: a contemporary review

Although fertility is frequently impaired in women with acromegaly, pregnancy is apparently becoming more common due to improvement in acromegaly treatment as well as in fertility therapy. As a result, several studies on pregnancy in patients with acromegaly have been published in recent years adding new and relevant information to the preexisting literature. Also, new GH assays with selective specificities and the knowledge of the expression of the various GH genes have allowed a better understanding of somatotrophic axis function during pregnancy. In this review, we show that pregnancy in women with acromegaly is generally safe, usually with tumoral and hormonal stability. Although the paucity of data limits evidence-based recommendations for preconception counseling and pregnancy surveillance, controlling tumor size and hormonal activity before pregnancy is highly recommended to ensure better outcomes, and surgical control should be attempted when feasible. Treatment interruption at pregnancy confirmation has also proven to be safe, as drugs are not formally allowed to be used during pregnancy. Drug exposure (somatostatin analogs) during early or whole pregnancy might increase the chance of a lower birth weight. Aggressive disease is uncommon and may urge individual decisions such as surgery or drug treatment during pregnancy or lactation.

Pre-diagnosis insulin-like growth factor-I and risk of epithelial invasive ovarian cancer by histological subtypes: A collaborative re-analysis from the Ovarian Cancer Cohort Consortium

PURPOSE

Biologic evidence suggests that the Insulin-like growth factor (IGF)-family may be involved in the etiology of epithelial invasive ovarian cancer (EOC). However, prospective studies investigating the role of IGF-I in ovarian carcinogenesis have yielded conflicting results.

METHODS

We pooled and harmonized data from 6 case-control studies nested within the Ovarian Cancer Cohort Consortium to investigate the association between pre-diagnosis IGF-I concentrations and subsequent risk of EOC. We evaluated IGF-I concentrations and risk of EOC overall and by tumor subtype (defined by histology, grade, stage) in 1,270 cases and 2,907 matched controls. Multivariable conditional logistic regression models were used to calculate odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Doubling of IGF-I concentration was associated with significantly lower risk of overall EOC [ORlog2 = 0.82; CI 0.72-0.93]. We observed no heterogeneity by tumor characteristics (e.g., histology, p het = 0.62), menopausal status at blood collection (p het = 0.79), or age at diagnosis (p het = 0.60).

CONCLUSIONS

These results suggest that IGF-I concentrations are inversely associated with EOC risk, independent of histological phenotype. Future prospective research should consider potential mechanisms for this association, including, considering other members of the IGF-family to better characterize the role of IGF-signaling in the etiology of EOC.

EXERCISE EFFECT ON PLACENTAL COMPONENTS: SYSTEMATIC REVIEW AND META-ANALYSIS

Physical exercise has been demonstrated a positive effect on many pregnancy outcomes. Placental components are important for exchanging oxygen and nutrients between mother and fetus. This study aimed to systematic review and meta-analysis whether physical exercise could induce a morphological adjustment on placenta components. We systematically searched PubMed database until October 30th, 2014. We included randomized and non-randomized studies with control group, which aimed to investigate the effect of the physical exercise (water, aerobic and resistance) on placental components (placental weight and volume, villous volume and vascular volume, intervillous space and stem villi). Initially, we identified 222 articles, of which 9 articles were used for full text analysis. Finally, four articles were included in the systematic review and meta-analysis. Meta-analysis demonstrated that exercise appeared to affect placental weight (95% CI, 39.73g [4.66-74.80]), placental volume (95% CI, 47.11 cm3 [37.99-56.23]), intervillous space (95% CI, 16.76 cm3 [12.66-20.68]), villous volume (95% CI, 46.01 cm3 [40.21-51.81]), villous vascular volume (95% CI, 15.95 cm3 [7.83-24.07]) and stem villi (95% CI, 6.00 cm3[4.25-7.75]). Apparently, physical exercise has a positive effect on placental components. However, this conclusion is based on a limited number of studies. Clearly, it stands the necessity of larger samples and better methodology quality.

Fetal growth and subsequent maternal risk of thyroid cancer

Thyroid cancer has peak incidence among women of reproductive age, and growth factors, which have procarcinogenic properties, may play an important etiologic role. However, the association between fetal growth rate during a woman's pregnancy and her subsequent risk of thyroid cancer has not been previously examined. We conducted a national cohort study of 1,837,634 mothers who had a total of 3,588,497 live-births in Sweden in 1973-2008, followed up for thyroid cancer incidence through 2009. There were 2,202 mothers subsequently diagnosed with thyroid cancer in 36.8 million person-years of follow-up. After adjusting for maternal age, height, weight, smoking, and sociodemographic factors, high fetal growth (birth weight standardized for gestational age and sex) was associated with a subsequent increased risk of thyroid cancer in the mother (incidence rate ratio [IRR] per additional 1 standard deviation, 1.05; 95% CI, 1.01-1.09; p = 0.02). Each 1,000 g increase in the infant's birth weight was associated with a 13% increase in the mother's subsequent risk of thyroid cancer (IRR, 1.13; 95% CI, 1.05-1.22; p = 0.001). These findings appeared to involve both papillary and follicular subtypes, and did not vary significantly by the mother's height, weight or smoking status. In this large national cohort study, high fetal growth during a woman's pregnancy was independently associated with a subsequent increased risk of her developing thyroid cancer. If confirmed, these findings suggest an important role of maternal growth factors in the development of thyroid cancer, and potentially may help facilitate the identification of high-risk subgroups of women.

Windows of opportunity for physical activity in the prevention of obesity

Tackling increasing rates of obesity is likely to be a defining feature of health care over the next several decades. Adult obesity is a persistent and treatment-resistant problem. Consequently, an emerging theme in the literature is to commence prevention efforts earlier in the developmental time course. This view is based primarily on epidemiological data demonstrating a link between traits manifesting early during development and increased obesity risk in adulthood. Physical activity is a perennial factor in discussions of obesity prevention. However, the optimal timing and type of physical activity interventions to commence remains unclear. Critical developmental windows of plasticity may afford time-limited opportunities to shape body composition across the life course; however, physical activity has not been explicitly considered in these discussions. Although animal models suggest that physical activity commenced earlier in development has differential effects on obesity onset compared to physical activity commenced in adulthood, human research is lacking. In this conceptual review, we consider physical activity during critical developmental periods as a way to mitigate obesity risk later in life.

Decreased IGF-1 concentration during the first trimester of pregnancy in women with normal somatotroph function

INTRODUCTION

A decrease of insulin-like growth factor-I levels (IGF-I) has been reported during the first trimester of pregnancy in women with acromegaly before the secretion of placental growth hormone (GH) progressively increases IGF-1 concentration.

STUDY DESIGN

To evaluate variations of concentrations of IGF-1, insulin-like growth factor (IGF)-binding protein-3 (IGF-BP3) and GH during the first trimester of pregnancy in women with normal somatotroph function.

PATIENTS AND METHODS

Sixteen women (median age 31 years) with as who were followed for benign thyroid disorders (n = 15) or prolactin-secreting microadenoma (n = 1) were evaluated before and in the first trimester of pregnancy. Serum concentrations of GH, IGF-1, IGF-BP3, TSH and estradiol (E2) were measured before and in the first trimester (5.4 ± 2.2 weeks of gestation).

RESULTS

Before pregnancy, somatotroph and thyroid functions (median TSH 1.2 mU/L) were normal in all women. At the first trimester IGF-1 levels decreased significantly (before = 210 ng/mL, first trimester = 145 ng/mL, p < 0.001) with no significant change in GH (before = 1.5 ng/mL, first trimester = 0.84 ng/mL) or IGF-BP3 levels (before = 2.3 ng/mL, first trimester = 2.2 ng/mL), while estradiol levels increased significantly (before = 46.5 pg/100 mL, first trimester = 448.5 pg/100 mL, p < 0.001).

CONCLUSION

In women with normal somatotroph function, IGF-1 levels decrease in the first trimester of pregnancy without changes in GH or IGF-BP3 levels. These results confirm liver resistance to GH as a consequence of the physiological increase of estrogens during the first trimester.

Early pregnancy IGF-I and placental GH and risk of epithelial ovarian cancer: A nested case-control study

Insulin-like growth factor-I (IGF-I) signaling may promote ovarian tumor development by exerting mitotic, antiapoptotic and proangiogenic effects. During pregnancy, maternal production of IGF-I is regulated by placental growth hormone (GH). Parity is an established protective factor for ovarian cancer, however, no prior study has evaluated placental GH and IGF-I in pregnancy and epithelial ovarian cancer (EOC). Prior prospective studies on the association between IGF-I and EOC in nonpregnant populations were inconclusive and did not address associations in subtypes of EOC. Among members of the Finnish Maternity Cohort and the Northern Sweden Maternity Cohort, we identified 1,045 EOC cases, diagnosed after recruitment (1975-2008) and before March 2011 and 2,658 individually matched controls. Placental GH and IGF-I were measured in serum from the last pregnancy before EOC diagnosis or selection as control. We used conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for tertiles and a doubling of hormone concentrations. Higher IGF-I was associated with a nonsignificant decrease in risk for invasive [ORT3 vs. T1 : 0.79 (0.62-1.02); ptrend  = 0.07] and endometrioid tumors [ORT3 vs. T1 : 0.55 (0.28-1.07); ptrend  = 0.07]. The protective association between higher IGF-I levels and risk of invasive EOC was stronger in analyses limited to women aged <55 years at diagnosis [ORT3 vs. T1 : 0.74 (0.57-0.96); ptrend  = 0.03]. Our study provides the first data on placental GH and IGF-I in pregnancy and EOC risk overall and by subtype. Our data suggest higher IGF-I levels in pregnancy may be associated with lower risk of invasive and endometrioid EOC.

Fetal growth and subsequent maternal risk of colorectal cancer

BACKGROUND

High birth weight has been associated with subsequent increased risk of breast cancer in the infant's mother, possibly related to maternal estrogen and growth factor pathways. However, its association with maternal risk of colorectal cancer, the third most common cancer among women, is unknown.

METHODS

We conducted a national cohort study of 1,838,509 mothers who delivered 3,590,523 babies in Sweden in 1973-2008, followed up for colorectal cancer incidence through 2009.

RESULTS

There were 7,318 mothers diagnosed with colorectal cancer in 36.8 million person-years of follow-up. After adjusting for maternal age, body mass index, diabetes, and other potential confounders, high fetal growth was associated with a subsequent increased risk of colorectal cancer in the mother [incidence rate ratio (IRR) per additional 1 SD relative to mean birth weight for gestational age and sex, 1.05; 95% confidence intervals (CI), 1.03-1.07; P < 0.0001]. Each 1,000 g increase in the infant's birth weight was associated with a 12% increase in the mother's subsequent risk of colorectal cancer (IRR, 1.12; 95% CI, 1.07-1.17; P < 0.0001). Multiple gestation was also independently associated with increased maternal risk of colorectal cancer (IRR for twin or higher order vs. singleton, 1.22; 95% CI, 1.04-1.44; P = 0.02).

CONCLUSION

In this large cohort study, high fetal growth and multiple gestation were independently associated with subsequent higher maternal risk of colorectal cancer. These findings warrant further investigation of maternal growth factor and estrogen pathways in the etiology of colorectal cancer.

IMPACT

If confirmed, our findings may help identify subgroups of women at high risk of colorectal cancer.

Insulin-like growth factor-1 is associated with life-history variation across Mammalia

Despite the diversity of mammalian life histories, persistent patterns of covariation have been identified, such as the 'fast-slow' axis of life-history covariation. Smaller species generally exhibit 'faster' life histories, developing and reproducing rapidly, but dying young. Hormonal mechanisms with pleiotropic effects may mediate such broad patterns of life-history variation. Insulin-like growth factor 1 (IGF-1) is one such mechanism because heightened IGF-1 activity is related to traits associated with faster life histories, such as increased growth and reproduction, but decreased lifespan. Using comparative methods, we show that among 41 mammalian species, increased plasma IGF-1 concentrations are associated with fast life histories and altricial reproductive patterns. Interspecific path analyses show that the effects of IGF-1 on these broad patterns of life-history variation are through its direct effects on some individual life-history traits (adult body size, growth rate, basal metabolic rate) and through its indirect effects on the remaining life-history traits. Our results suggest that the role of IGF-1 as a mechanism mediating life-history variation is conserved over the evolutionary time period defining mammalian diversification, that hormone-trait linkages can evolve as a unit, and that suites of life-history traits could be adjusted in response to selection through changes in plasma IGF-1.

Insulin-like growth factor binding protein-1 (IGFBP-1) during normal pregnancy

BACKGROUND

Insulin-like growth factor (IGF) binding protein-1 (IGFBP-1) is the main binder of IGFs in secretory endometrium and decidualized stromal endometrial cells and IGFBP-1 has been shown to modulate IGF bioactivities and influence fetal growth. To be able to evaluate IGFBP-1 values during pregnancy it is important to establish normal values in pregnant women.

MATERIALS & METHODS

We have studied IGFBP-1 concentrations in maternal plasma from 52 healthy women with normal singleton pregnancies. Several plasma samples were collected from each woman and the samples were grouped according to gestational age into the following periods: week 7-17; week 17-24; week 24-28; week 28-31; week 31-34; week 34-38; -2 to 0 weeks prior to delivery and postpartum (>6 weeks after delivery).

RESULTS

The 2.5 and 97.5 percentiles for IGFBP-1 were calculated according to the recommendations of the International Federation of Clinical Chemistry on the statistical treatment of reference values.

CONCLUSIONS

IGFBP-1 is increased during pregnancy compared to postpartum. Two peaks, at week 17-24 and just before delivery, were observed.

Chemerin is present in human cord blood and is positively correlated with birthweight

OBJECTIVE

Chemerin, a novel adipokine, has been implicated in adipogenesis, inflammation, and metabolism. The aims of this study were to determine the presence of chemerin in cord blood and its association with birthweight.

STUDY DESIGN

This cross-sectional study included the following: (1) twins with (n = 24) or without (n = 28) birthweight discordancy; and (2) singletons subclassified into small-for-gestational-age (SGA; n = 18); appropriate for gestational age (AGA; n = 33); and large-for-gestational-age (LGA; n = 8). Cord blood chemerin was determined. Parametric and nonparametric statistics were used for analysis.

RESULTS

The results of the study included the following: (1) within the discordant twins group, the median chemerin concentration was significantly lower in the SGA group than in their cotwins; (2) within singletons, the median chemerin concentration was significantly higher in the LGA than the AGA newborns; and (3) the regression model revealed that chemerin was independently associated with birthweight.

CONCLUSION

Cord blood chemerin is present in cord blood and its concentrations are positively correlated with birthweight. These novel findings support a role of adipokines in fetal growth.

Effects of Diet and Exercise on Insulin Resistance during Pregnancy

Current evidence suggests that both diet and exercise can alter the usual increase in insulin resistance seen in Western societies during mid and late pregnancy. A low-glycemic diet combined with a low-volume exercise regimen during pregnancy decreases the glucose and insulin response to both mixed caloric intake and exercise, and probably lowers both 24-h blood glucose concentrations and the maternal substrate utilization ratio of carbohydrate/fat. The end result is a marked decrease in both maternal weight gain and size at birth. Regular weight-bearing exercise alone lowers markers of insulin resistance and lowers blood glucose concentration during and immediately after exercise during pregnancy. Changes in diet and/or physical activity appear to prevent the onset of gestational diabetes mellitus in at-risk women and may be of value in the treatment of those who develop gestational diabetes.

Placental weight and breast cancer risk in young women: a registry-based cohort study from Norway

BACKGROUND

Pregnancy has a short-term risk-increasing effect on breast cancer that may be attributed to growth-promoting effects of pregnancy hormones on prevalent but undetected tumors. Results of two previous studies suggested that placental weight may be positively associated with breast cancer risk.

METHODS

In a cohort of 338,051 women followed from 1999 to 2008, on the basis of data linkage between the Medical Birth Registry of Norway and the Cancer Registry of Norway, we assessed whether placental weight in a woman's most recent pregnancy was related to breast cancer risk during the first years following pregnancy.

RESULTS

During follow-up (median, 6.0 years; interquartile range, 3.0-8.3 years), 648 women were diagnosed with breast cancer at a mean age of 38.4 years (standard deviation, 5.3 years). Placental weight in the most recent pregnancy was not associated with breast cancer risk: the hazard ratio per 100-gram increase in placental weight was 1.03 [95% confidence interval, 0.96-1.10]. There was a similar lack of association related to mean placental weight across pregnancies and to placental weight associated with the first birth.

CONCLUSION

We could not confirm previous reports that women who develop large placentas are at increased risk of breast cancer.

IMPACT

The epidemiologic support for an association of placental weight with breast cancer risk remains inconclusive. More research is needed to identify factors that influence breast cancer risk in young women.

Can we modify the intrauterine environment to halt the intergenerational cycle of obesity?

Child obesity is a global epidemic whose development is rooted in complex and multi-factorial interactions. Once established, obesity is difficult to reverse and epidemiological, animal model, and experimental studies have provided strong evidence implicating the intrauterine environment in downstream obesity. This review focuses on the interplay between maternal obesity, gestational weight gain and lifestyle behaviours, which may act independently or in combination, to perpetuate the intergenerational cycle of obesity. The gestational period, is a crucial time of growth, development and physiological change in mother and child. This provides a window of opportunity for intervention via maternal nutrition and/or physical activity that may induce beneficial physiological alternations in the fetus that are mediated through favourable adaptations to in utero environmental stimuli. Evidence in the emerging field of epigenetics suggests that chronic, sub-clinical perturbations during pregnancy may affect fetal phenotype and long-term human data from ongoing randomized controlled trials will further aid in establishing the science behind ones predisposition to positive energy balance.

Efeitos do treinamento físico durante a gestação sobre a evolução ponderal, glicemia e colesterolemia de ratos adultos submetidos à desnutrição perinatal

A incompatibilidade entre a desnutrição perinatal e uma nutrição adequada durante o desenvolvimento aumenta o risco de aparecimento precoce de doenças não transmissíveis na vida adulta. Todavia, acredita-se que a atividade física materna possa atenuar estas consequências. O presente estudo teve como objetivo avaliar os efeitos do treinamento físico durante a gestação na evolução ponderal, circunferência abdominal, glicemia e colesterolemia de filhotes adultos submetidos à desnutrição perinatal. Ratas Wistar (n = 12) foram divididas em quatro grupos: controle (C, n = 3), treinada (T, n = 3), desnutrida (D, n = 3) e treinada desnutrida (T+D, n = 3). Durante a gestação e lactação, os grupos D e T+D receberam dieta baixa em proteína (8% caseína) e os grupos C e T receberam dieta normoproteica (caseína a 17%). O protocolo de treinamento físico moderado foi realizado em esteira ergométrica (cinco dias/semana, 60 min/dia, a 65% do VO2max) e iniciou quatro semanas antes da gestação. Na gestação, a duração e a intensidade do treinamento foram reduzidas (cinco dias/semana, 20 min/dia, a 30% do VO2max) até o 19º dia pré-natal. Após o desmame, os filhotes (C F = 9, T F = 9, D F = 7, T+D F = 9) receberam dieta padrão de biotério e foram avaliados aos 270 dias de idade. A circunferência abdominal (CA) foi avaliada relativa ao peso corporal. Para avaliação da glicemia e colesterolemia foi utilizado o método enzimático colorimétrico da glicose-oxidase/peroxidase e da colesterol-oxidase, respectivamente. Ratos do grupo D F apresentaram um maior ganho de peso corporal ao longo do crescimento, maiores valores de CA, glicemia e colesterolemia quando comparados ao grupo C F. Para o grupo T+D F, o ganho de peso foi atenuado, e a CA, a glicemia e a colesterolemia foram normalizadas (p < 0,05). Esses resultados demonstram que o treinamento físico durante a gestação atenua os efeitos da desnutrição perinatal sobre alguns indicadores murinométricos e bioquímicos nos filhotes adultos.

Maternal concentrations of insulin-like growth factor I and insulin-like growth factor binding protein 1 during pregnancy and birth weight of offspring

Maternal concentrations of insulin-like growth factor I (IGF-I) and insulin-like growth factor binding protein 1 (IGFBP-1) may influence fetal growth. Offspring birth weight related to maternal IGF-I and IGFBP-1 measured in pregnancy was studied in 368 randomly selected women without preeclampsia who delivered a singleton liveborn child in Norway between 1992 and 1994. Maternal IGF-I concentrations were not consistently associated with birth weight, but a 1-standard deviation stronger increase in IGF-I from the first to second trimester was associated with an 82-g (95% confidence interval (CI): 11, 153) higher birth weight. IGFBP-1 concentrations were inversely associated with birth weight: Birth weight was 71 g (95% CI: 14, 128) lower per 1-standard deviation higher IGFBP-1 in the second trimester, and an increase in IGFBP-1 from the first (below median) to second (above median) trimester was associated with a 342-g (95% CI: 124, 560) lower birth weight, compared with having low IGFBP-1 (below median) in both trimesters. Conversely, low IGFBP-1 in both trimesters was associated with a 200-350-g higher birth weight compared with other combinations of IGFBP-1. In conclusion, persistently low IGFBP-1 in pregnancy is associated with relatively higher birth weight. Maternal insulin resistance may provide a link between IGFBP-1 and offspring birth weight.

Effects of exercise training on maternal hormonal changes in pregnancy

CONTEXT & OBJECTIVE

A recent paper by our group reported that regular aerobic exercise during pregnancy led to lower foetal IGF-I and IGF-II concentrations and a modest reduction in offspring birth weight when compared with the offspring of nontraining control participants. Maternal hormonal alterations in response to exercise training may be associated with the regulation of nutrient availability for foetal growth through placental regulation of maternal metabolism.

OBJECTIVE

To determine whether the reduction in offspring size was associated with changes in the maternal IGF axis [including placental growth hormone (PGH)], leptin and/or free fatty acids (FFA) in response to aerobic exercise training in the second half of pregnancy.

DESIGN AND SETTING

A randomized, controlled trial of exercise in pregnancy.

PATIENTS

Eighty-four healthy nulliparous women (mean±SD age 30±4 year, BMI 25·5±4 kg/m(2) ).

MEASUREMENTS

Serum samples were drawn at 19 and 35 weeks gestation to determine serum IGF-I, IGF-II, IGF-binding protein-1, IGF-binding protein-3, PGH, leptin and FFA.

RESULTS

Exercise training in pregnancy had no impact on the pregnancy-related changes in the maternal IGF axis. Women in the exercise group experienced a 29% increase in leptin in late gestation (P=0·026 vs control) and a trend towards lower FFA (P=0·07 vs control). Late pregnancy changes in maternal leptin were inversely related to offspring birth weight (r= -0·24, P<0·05) and BMI (r= -0·25, P<0·05).

CONCLUSIONS

An increase in leptin in exercising pregnant women may reflect subtle changes within the placenta in response to regular exercise and may contribute to the reduction in offspring size previously reported in this cohort.

Maternal serum concentrations of insulin-like growth factor (IGF)-I and IGF binding protein-1 before and during pregnancy in relation to maternal body weight and composition and infant birth weight

Maternal nutritional status, e.g. body weight and composition, is associated with fetal growth. It has been suggested that the insulin-like growth factor (IGF) system may be a mediator of this relationship. In twenty-three healthy Swedish women, we studied (1) the relationships before and during pregnancy between maternal serum concentrations of IGF-I and IGF binding protein-1 (IGFBP-1) and maternal body weight and composition; (2) interactions between serum concentrations of IGF-I (before and in early pregnancy) and maternal nutritional status in relation to infant birth weight. We found that serum IGF-I during pregnancy was positively correlated with maternal body weight (r 0.47-0.56) and fat-free body weight (r 0.61-0.65), whereas serum IGFBP-1 was negatively correlated with maternal body weight (r - 0.44 to - 0.69) and body fat (r - 0.64 to - 0.76) before and during pregnancy. Women with a lower body fat content (%) before pregnancy had greater increases in serum IGFBP-1 during pregnancy than women with a higher prepregnant body fat content (%). In addition, significant fractions of the variation in corrected infant birth weight were explained by variables related to the maternal nutritional status when these were combined with serum concentrations of IGF-I in gestational week 14 (adjusted r2 0.25-0.44, P = 0.001-0.021), but not when they were combined with such concentrations before pregnancy (adjusted r2 0.11-0.12, P = 0.105-0.121). These results suggest mechanisms by which the IGF system may be a mediator between maternal nutritional status and fetal growth.

Hormonal and metabolic factors associated with variations in insulin sensitivity in human pregnancy

OBJECTIVE

The objective of this study was to determine maternal hormonal and metabolic factors associated with insulin sensitivity in human pregnancy.

RESEARCH DESIGN AND METHODS

This was a prospective observational cross-sectional study of 180 normal pregnant women, using samples collected at the time of a blinded oral glucose tolerance test (OGTT) between 24 and 32 weeks' gestation as an ancillary to the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study. The study was conducted at two public university teaching hospitals, Cleveland, Ohio, and Brisbane, Australia. Fasting maternal serum cholesterol, triglycerides, free fatty acids, insulin, leptin, tumor necrosis factor-alpha, placental growth hormone (PGH), insulin-like growth factors (IGFs) 1 and 2, and insulin-like growth factor binding proteins (IGFBPs) 1 and 3 were assayed. Correlation and multiple regression analyses were used to determine factors associated with maternal insulin sensitivity (IS) estimated using both OGTT-derived (IS(OGTT)) and fasting (using the homeostasis model assessment [HOMA]; IS(HOMA)) insulin and glucose concentrations.

RESULTS

Insulin sensitivity correlated (r = x and y for IS(OGTT) and IS(HOMA,) respectively) with fasting maternal serum leptin (-0.44 and -0.52), IGFBP1 (0.42 and 0.39), and triglycerides (-0.31 and -0.27). These factors were significantly associated with insulin sensitivity in multiple regression analyses (adjusted R(2) 0.44 for IS(OGTT) and IS(HOMA)). These variables explained more than 40% of the variance in estimates of insulin sensitivity.

CONCLUSIONS

Maternal hormonal and metabolic factors related to the placenta, adipose tissue, and the growth hormone axis are associated with the variation in insulin sensitivity seen during normal human pregnancy.

The unique characteristics of ovarian carcinogenesis in the adolescent and young adult population

Ovarian cancer in the adolescent and young adult (AYA) population is a disease that is distinctly different with regard to risk factors, genetics, and pathology when compared to ovarian cancers occurring in older women. This article will review the theories behind ovarian carcinogenesis and attempt to elucidate why these tumors exhibit their unique biologic characteristics. Knowledge of these differences will allow us to begin to develop strategies for future research endeavors enabling improved survival in AYA women diagnosed with ovarian cancer.

The association between birth weight, season of birth and latitude

BACKGROUND

Birth weight is known to fluctuate with month of birth and with latitude; however the mechanisms underlying these gradients remain unclear.

AIM

The study examined within-year fluctuations in birth weight across four regions in Australia.

SUBJECTS AND METHODS

We obtained the birth weight of singleton births of at least 37 weeks gestation from four regions: (a) southeast Queensland, (b) Sydney and surrounding districts, (c) Victoria, and (d) Tasmania. Seasonal fluctuations were examined after long-term trends had been removed. The amplitude, timing and variability of seasonal fluctuations were examined and compared across regions.

RESULTS

Each of the four regions had prominent annual periodicity with the peak birth weight occurring in spring. The amplitude of this signal ranged from 1.4 g (Victoria) to 7.7 g (southeast Queensland). There was no significant correlation between the amplitude of these fluctuations and the latitude of four regions. In addition, a second smaller autumn peak was identified.

CONCLUSION

Environmental factors that have regular within-year variation influence birth weight in Australia. The evidence suggests that at least two distinguishable seasonal processes contribute to the findings. Identifying the factors underlying these seasonal fluctuations could have implications from a public health perspective.

Endocrine regulation in asymmetric intrauterine fetal growth retardation

OBJECTIVE

The ponderal index (PI) is a widely accepted measure of disproportionate growth or asymmetrical growth retardation by pediatricians worldwide. Identification of disproportionately grown small for gestational age (SGA) neonates by using the ponderal index as a measure of the nutritional status at birth, is important because they constitute a high-risk group among SGA neonates. Poor nutritional status of the mother could have a direct effect on the organs of the developing fetus and/or affect the endocrine milieu in the maternal feto-placental unit resulting in an increased incidence of intrauterine growth-retarded (IUGR)/SGA births. IUGR is a significant risk factor for adult disease. In this study, we have investigated the endocrine adaptation by the fetus to overcome the growth disadvantage caused due to poor nutritional status of the mother.

MATERIALS AND METHODS

We examined the quantitative variations in hormonal and growth factor profiles in paired maternal and cord blood samples obtained from mothers and their neonates who were classified based on their growth status into SGA and appropriate for gestational age (AGA).

RESULTS

(1) A total of 24.7% neonates had a PI < 2, indicating a high incidence of asymmetric IUGR in the population studied. (2) Anthropometric parameters measured in the mothers indicate that the mothers giving birth to neonates with a PI < 2 had poor nutritional status, both prior to and during pregnancy. (3) We observed increased levels of placental lactogen and prolactin and decreased levels of insulin in the cord blood of neonates with PI < 2, while lower levels of insulin-like growth factor 1 (IGF-1) and higher levels of epidermal growth factor (EGF) were observed in their mothers.

CONCLUSION

Poor maternal nutritional status results in fetal adaptation to a growth restricted environment via the modulation of the pituitary-thyroid axis thereby altering the endocrine milieu, thus affecting fetal growth.

Placental weight and risk of invasive epithelial ovarian cancer with an early age of onset

BACKGROUND

Epithelial ovarian cancer is associated with reproductive factors, but we lack knowledge if hormonal factors during pregnancy influence the mother's risk. Because pregnancy hormones are primarily produced by the placenta, placental weight may be an indirect marker of hormone exposure during pregnancy.

METHODS

In a nationwide Swedish cohort study, we included women with singleton births from 1982 to 1989. Women were followed for occurrence of invasive epithelial ovarian cancer, death, or emigration through 2004. Hazard ratios (HR) with 95% confidence intervals (95% CI) from Cox models were used to estimate associations between pregnancy exposures and epithelial ovarian cancer.

RESULTS

Among 395,171 women with information on placental weight in their first recorded birth, 316 women developed invasive epithelial ovarian cancer. Mean age at diagnosis was 44 years. Compared with women with a placental weight of 500 to 699 g, women with a high (>or=700 g) placental weight had an increased risk of developing epithelial ovarian cancer (HR, 1.47; 95% CI, 1.14-1.90). Compared with women with term pregnancies (40-41 weeks), women with post-term (>or=42 weeks) pregnancies had an increased risk of developing epithelial ovarian cancer (HR, 1.48; 95% CI, 1.00-2.19). These associations were slightly stronger when we included information about women's overall first birth, and slightly weaker when we included information about last recorded birth or ever last birth from 1982 to 1989.

CONCLUSIONS

Because pregnancy hormone levels increase with placental weight, our study supports the hypothesis that hormone exposures during pregnancy influence the risk of invasive epithelial ovarian cancer among young women.

Single gene mutations causing SGA

The growth hormone-insulin-like growth factor-I (GH-IGF-I) axis plays a key role in intra-uterine growth and development. This review will describe the consequences of genetic defects in various components of the GH-IGF-I axis on intra-uterine growth and development. Animal knockout experiments have provided evidence for the GH-independent secretion of IGF-I and its effect in utero. Reports of patients with a deletion or mutation of the IGF-I and IGF1R genes have provided insight into the role of intra-uterine IGF-I in the human. Homozygous defects of the IGF-I gene have dramatic effects on intra-uterine growth and development, whereas heterozygous defects of the IGF1R gene have a more variable clinical presentation. The phenotype in relation to the genotype of the different disorders will be reviewed in this chapter.

Placenta and fetal growth restriction

The placenta, as the vector for all maternal-fetal oxygen and nutrient exchange, is a principal influence on birthweight. Placental weight summarizes laterally expanding growth of the chorionic disc, and villous arborization yielding the nutrient exchange surface. These different growth dimensions alter fetoplacental weight ratio and ponderal index, and thus may modify placental functional efficiency. The placenta may show a range of histopathologies, some of which are also associated with fetal growth restriction. Different fetal intrinsic abilities to compensate for gross and histo-pathology may clarify the imperfect relationships between fetal growth and both intrauterine pathology, and the long-term health risks associated with poor fetal growth.

Longitudinal study of the maternal insulin-like growth factor system before, during and after pregnancy in relation to fetal and infant weight

BACKGROUND

The maternal insulin-like growth factor (IGF) system is considered to be involved in fetal growth regulation. However, available data linking this system to fetal growth are contradictory and incomplete.

AIMS

To measure components of the IGF system before, during and after pregnancy in healthy women and to relate these results, and their changes during pregnancy, to fetal weight (gestational week 31) and birth weight.

METHODS

Serum concentrations of IGF-I, IGF-II, IGF-binding protein (IGFBP)-1, IGFBP-3 and IGFBP-3 protease activity were assessed in 23 women before conception, at weeks 8, 14, 20, 32 and 35 of pregnancy and 2 weeks postpartum. The data were analyzed using simple and multiple linear regression.

RESULTS

One third of the variability in fetal weight was explained by IGF-I in combination with IGFBP-3 protease activity, both assessed at gestational week 32 (p = 0.013). Birth weight was negatively correlated (r = -0.43 to -0.59) with IGFBP-1 at gestational week 20 (p = 0.041), 32 (p = 0.012) and 35 (p = 0.003).

CONCLUSION

We propose there is a finely tuned balance among the components of the IGF system, providing a means for fetal growth regulation.

Insulin-like Growth Factor I in Pregnancy and Maternal Risk of Breast Cancer

BACKGROUND

The role of insulin-like growth factor (IGF)-I in breast cancer remains controversial, despite numerous reports on the association of the hormone with breast cancer or high-risk mammographic densities. We hypothesized that exposure to elevated IGF-I during early pregnancy, a period characterized by intense cell proliferation in the breasts and in the presence of high concentrations of sex steroids, will be associated with increased maternal risk to develop a breast malignancy.

METHODS

The Northern Sweden Maternity Cohort is an ongoing prospective study, collecting blood samples from first-trimester-pregnant women since 1975 as part of screening for infectious diseases. A case-control study (212 cases and 369 controls) was nested among Northern Sweden Maternity Cohort members who delivered singleton babies. RIA was used to measure IGF-I and IGF-II levels. Conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI).

RESULTS

Breast cancer risk increased with increasing IGF-I (top tertile OR, 1.7; 95% CI, 1.1-2.7). The association was stronger among the primiparous (OR, 2.2; 95% CI, 1.1-4.4) than in the nonprimiparous women (OR, 1.4; 95% CI, 0.7-2.8). Upper-tertile risks seemed to decrease within the <28-, 28 to 33, and >33-year groups of age at sampling, from 2.5 (0.9-7.6) to 2.1 (0.9-5.0) and 1.2 (0.5-2.5), respectively. There was no association of breast cancer with first-trimester-pregnancy IGF-II.

CONCLUSIONS

The study offers further evidence that IGF-I is important in breast cancer. Our findings suggest that the adverse effect of IGF-I on the breast may be stronger before the remodeling of the gland induced by a first pregnancy.

A variable degree of intrauterine and postnatal growth retardation in a family with a missense mutation in the insulin-like growth factor I receptor

CONTEXT

The type 1 IGF-I receptor (IGF1R) mediates the biological functions of IGF-I. Binding of IGF-I to the IGF1R results in autophosphorylation of the intracellular beta-subunit and activation of intracellular signaling.

OBJECTIVE

The objective of this study was to evaluate the functional characteristics of a novel IGF1R mutation and describe the phenotypic features of two patients with this mutation.

DESIGN

The study was performed in a university hospital.

PATIENTS

We describe a 35-yr-old female with mild intrauterine growth failure, progressive postnatal growth retardation, severe failure to thrive, and microcephaly. Her daughter was born with severe intrauterine growth retardation and also showed postnatal failure to thrive and microcephaly.

RESULTS

We found a heterozygous G3148-->A nucleotide substitution in the IGF1R gene, changing a negatively charged glutamic acid at position 1050 into a positively charged lysine residue (E1050K). E1050 is a conserved residue in the intracellular kinase domain. Dermal fibroblasts of the mother showed normal binding of iodinated IGF-I, but autophosphorylation and activation of downstream signaling cascades upon challenging with IGF-I was markedly reduced. Consequently, the maximal [(3)H]thymidine incorporation upon challenge with a dose range of IGF-I was reduced compared with a panel of control cells (3.65 +/- 1.79-fold vs. 6.75 +/- 4.7-fold stimulation; P < 0.01). These data suggest that the mutation results in the inactivation of one copy of the IGF1R gene.

CONCLUSIONS

These two patients support the key role for IGF-I in intrauterine and postnatal growth. The different phenotypes of these and earlier described patients may be associated with variability in IGF-I signaling. The degree of intrauterine growth retardation may be partially determined by the presence or absence of maternal IGF-I resistance.

Expression of inhibins, activins, insulin-like growth factor-I and steroidogenic enzymes in the equine placenta

In this study, the expression patterns of inhibins, activins, insulin-like growth factor-I (IGF-I) and steroidogenic enzymes in equine placentae recovered during the latter two-thirds of gestation were examined. Concentrations of inhibin A and inhibin pro-alphaC in endometrial and fetal placental tissue homogenates were very low during the period examined, whereas these tissues contained high concentrations of activin A. In both maternal endometrial and fetal placental tissues, activin A levels decreased as pregnancy progressed. Expression of inhibin alpha-subunit was not observed in the placenta using either immunohistochemistry or in situ hybridization. Inhibin/activin betaA-subunit and its mRNA were confined to maternal endometrial glands, whereas immunopositive betaB-subunit was not detected in either endometrial glands or microcotyledons. Cytochrome P450 side chain cleavage enzyme was detected by immunohistochemistry in both endometrial glands and microcotyledons, whereas cytochrome P450 17alpha-hydroxylase/lyase was absent in these tissues. Immunopositive signals for 3beta-hydroxysteroid dehydrogenase and cytochrome P450 aromatase were localized in microcotyledons but not in endometrial glands. Immunohistochemistry revealed that IGF-I was highly expressed in microcotyledons around Day 130, and decreased as pregnancy progressed. Changes in the expression of IGF-I were correlated with the number of PCNA positive cells in the placenta. The present study demonstrated the presence and localized the site of expression of activin, IGF-I and steroidogenic enzymes in equine placental tissues during the latter two-thirds of gestation; the results suggest that activin and IGF-I may be involved in the regulation of placental development.

Influence of Endurance Exercise and Diet on Human Placental Development and Fetal Growth

The delivery of oxygen and substrate to the maternal-fetal interphase is the major maternal environmental stimulus which either up- or down-regulates feto-placental growth. During pregnancy, sustained exercise sessions cause an intermittent reduction in oxygen and substrate delivery to the interphase that may exceed 50% during the exercise but, it is probable that regular bouts of sustained exercise or exercise training may improve oxygen and substrate delivery at rest. The type of maternal carbohydrate intake (low- versus high-glycemic sources) and food intake frequency also influence substrate availability through their effects on maternal blood glucose levels and insulin sensitivity. As a result, different exercise regimens and/or different types of carbohydrate intake modify feto-placental growth. The magnitude and direction of the effect is determined by their average 24-h effect on oxygen and substrate availability at different time-points in pregnancy. In general, exercise in early and mid pregnancy stimulates placental growth while the relative amount of exercise in late pregnancy determines its effect on late fetal growth. Low-glycemic food sources in the diet decrease growth rate and size at birth while high-glycemic food sources increase it. Thus, it may be possible to improve pregnancy outcomes in both healthy, low-risk women and a variety of high-risk populaces by simply modifying maternal physical activity and dietary carbohydrate intake during pregnancy.

Determinants of fetal growth

Fetal growth is the end product of a variety of genetic, maternal, fetal, and placental factors. Maternal size is a dominant determinant of birth weight. Specific nutrients and their availability modify the expression of genetically determined metabolic and transfer systems. Hormones and growth factors of maternal, fetal, and placental origin regulate nutrient transfer and fetal organ development. Fetal development is ultimately determined by dynamic interactions between all of these factors beginning prior to conception and proceeding to delivery.