Early pregnancy weight gain and fat accrual predict pregnancy outcome in growing adolescent sheep.

The competition for nutrients when pregnancy coincides with continuing growth in biologically immature adolescent girls increases their risk of preterm delivery and low birthweight and is partly replicated in the overnourished adolescent sheep paradigm. Although overfeeding to promote rapid maternal growth robustly leads to a reduction in average birthweight relative to slow-growing control-fed adolescents of equivalent age, the extent of prenatal compromise is variable. This retrospective analysis of a large cohort of identically managed pregnancies determined whether maternal anthropometry predicts the severity of fetal growth-restriction (FGR) in growing adolescents. Singleton pregnancies were established by embryo transfer in adolescents subsequently control-fed (n = 96) or overnourished. The latter pregnancies were classified as non-FGR (n = 116) or FGR (n = 96) if lamb birthweight was above or below the optimally fed control mean minus 2SD. A similar approach categorised placental growth-restriction (PlGR) and preterm delivery. Gestation length, placental mass and lamb birthweight were FGR < non-FGR < control (post hoc P < 0.01). Relative to the non-FGR group, overnourished dams with FGR were marginally leaner and lighter at conception (P = 0.023/P = 0.014) and had greater gestational weight gain (GWG) during the first-third of pregnancy (P < 0.001). GWG during this early period was also higher in PlGR compared with non-PlGR, and in very preterm vs term deliveries (P < 0.01). Likewise maternal leptin concentrations (fat accrual biomarker) were FGR > non-FGR by day 60, and changes in leptin throughout pregnancy predicted attenuated fetal cotyledon mass and birthweight (P = 0.01 to <0.001). The anthropometric antecedents of FGR in still-growing adolescent sheep originate in early pregnancy coincident with early placental development.

Ovine prenatal growth restriction impacts glucose metabolism and body composition throughout life in both sexes.

Low birthweight is a risk factor for later adverse health. Here the impact of placentally mediated prenatal growth restriction followed by postnatal nutrient abundance on growth, glucose metabolism and body composition was assessed in both sexes at key stages from birth to mid-adult life. Singleton-bearing adolescent dams were fed control or high nutrient intakes to induce normal or growth-restricted pregnancies respectively. Restricted lambs had ~40% reduced birthweight. Fractional growth rates were higher in restricted lambs of both sexes predominantly during suckling/juvenile phases. Thereafter, rates and patterns of growth differed by sex. Absolute catch-up was not achieved and restricted offspring had modestly reduced weight and stature at mid-adulthood necropsy (~109 weeks). Dual-energy X-ray absorptiometry revealed lower bone mineral density in restricted vs normal lambs at 11, 41, 64 and 107 weeks, with males > females from 41 weeks onwards. Body fat percentage was higher in females vs males throughout, in restricted vs normal lambs at weaning (both sexes) and in restricted vs normal females at mid-adulthood. Insulin secretion after glucose challenge was greater in restricted vs normal of both sexes at 7 weeks and in restricted males at 32 weeks. In both sexes, fasting glucose concentrations were greater in restricted offspring across the life course, while glucose area under the curve after challenge was higher in restricted offspring at 32, 60, 85 and 106 weeks, indicative of persistent glucose intolerance. Therefore, prenatal growth restriction has negative consequences for body composition and metabolism throughout the life course with the effects modulated by sex differences in postnatal growth rates, fat deposition and bone mass accrual.

Impact of donor and recipient adiposity on placental and fetal growth in adolescent sheep.

The influence of maternal obesity during oocyte development and its putative interaction with nutrient reserves at conception on pregnancy outcome were examined in an adolescent sheep model. Donor ewes were nutritionally managed to achieve contrasting adiposity (control (CD)/obese (ObD)) for 6 weeks prior to superovulation and inseminated by a non-obese sire. Morulae from 6 CD and 7 ObD were transferred in singleton into adolescent recipients of identical age but differing adiposity, classified as relatively fat or thin respectively. Thereafter, all were overnourished to promote rapid growth/adiposity (2 × 2 design, 13/14 pregnancies/group). A fifth recipient group of intermediate adiposity received embryos from another 5 CD, was offered a moderate intake to maintain adiposity throughout gestation and acted as controls for normal pregnancy outcome (optimally treated control (OTC), 19 pregnancies). Donor obesity did not influence ovulation, fertilisation or recovery rates or impact embryo morphology. Gestation length and colostrum yield were unaffected by donor or recipient adiposity and were reduced relative to OTC. Total fetal cotyledon and lamb birth weights were independent of initial donor adiposity but reduced in relatively thin vs relatively fat recipients and lower than those in the OTC group. In spite of high placental efficiency, the incidence of fetal growth restriction was greatest in the thin recipients. Thus, maternal adiposity at conception, but not pre-conception maternal obesity, modestly influences the feto-placental growth trajectory, whereas comparison with the OTC indicates that high gestational intakes to promote rapid maternal growth remain the dominant negative influence on pregnancy outcome in young adolescents. These findings inform dietary advice for pregnant adolescent girls.

Peri- and Postnatal Effects of Prenatal Adenoviral VEGF Gene Therapy in Growth-Restricted Sheep.

Uterine artery (UtA) adenovirus (Ad) vector-mediated overexpression of vascular endothelial growth factor (VEGF) enhances uterine blood flow in normal sheep pregnancy and increases fetal growth in the overnourished adolescent sheep model of fetal growth restriction (FGR). Herein, we examined its impact on gestation length, neonatal survival, early postnatal growth and metabolism. Singleton-bearing ewes were evenly allocated to receive Ad.VEGF-A165 (5 × 10(10) particles/ml, 10 ml, n = 17) or saline (10 ml, n = 16) injected into each UtA at laparotomy (0.6 gestation). Fetal growth was serially monitored (blind) by ultrasound until delivery. Lambs were weighed and blood was sampled weekly and a glucose tolerance test performed (68-day postnatal age). Hepatic DNA/RNA was extracted at necropsy (83-day postnatal age) to examine methylation status of eight somatotropic axis genes. IGF1 mRNA and protein expression were measured by RT-PCR and radioimmunoassay, respectively. All pregnancies remained viable following Ad.VEGF-A165 treatment. Fetal abdominal circumference and renal volume were greater in the Ad.VEGF-A165 group compared with the saline group at 21/28 days (P ≤ 0.04) postinjection. At delivery, gestation length (P = 0.07), lamb birthweight (P = 0.08), umbilical girth (P = 0.06), and plasma glucose (P = 0.09) tended to be greater in Ad.VEGF-A165-treated lambs. Levels of neonatal intervention required to ensure survival was equivalent between groups. Absolute postnatal growth rate (P = 0.02), insulin area under the curve (P = 0.04) and carcass weight at necropsy (P = 0.04) were increased by Ad.VEGF-A165 treatment. There was no impact on markers of insulin sensitivity or methylation/expression of key genes involved in somatic growth. Ad.VEGF-A165 gene therapy increased fetal growth in a sheep FGR model, and lambs continued to thrive during the neonatal and early postnatal period.

Impact of embryo donor adiposity, birthweight and gender on early postnatal growth, glucose metabolism and body composition in the young lamb.

Intrauterine growth restriction (IUGR) is a risk factor for metabolic syndrome, notably when associated with rapid postnatal catch-up growth. A sheep paradigm was used to assess relationships between prenatal and early postnatal growth trajectories, metabolism and body composition. Singletons (single-sire embryo transfer from obese and control donors) were gestated and suckled by overnourished adolescent dams and categorised by birthweight as IUGR or normal (N). Gestation length was equivalent in both categories and all lambs were delivered spontaneously preterm (PT; mean (±s.e.m.) 139.8±1.7 days; term=145-147 days). The IUGR lambs were smaller at birth, but fractional growth rates (FGR) for eight anthropometry parameters were higher and independent of gender (except thorax girth; males (M)N; M>F) and first-phase insulin response (to 20min; IUGRF) and leptin (M

Inter-pregnancy weight change impacts placental weight and is associated with the risk of adverse pregnancy outcomes in the second pregnancy.

BACKGROUND: The inter-pregnancy period is considered a teachable moment when women are receptive to weight- management guidance aimed at optimising pregnancy outcome in subsequent pregnancies. In population based studies inter-pregnancy weight change is associated with several adverse pregnancy outcomes but the impact on placental size is unknown. METHODS: The association between inter-pregnancy weight change and the primary risk of adverse pregnancy outcomes in the second pregnancy was investigated in 12,740 women with first two consecutive deliveries at a single hospital using logistic regression. RESULTS: Compared with women who were weight stable, weight loss (>1BMI unit) between pregnancies was associated with an increased risk of spontaneous preterm delivery, low placental weight and small for gestational age (SGA) birth, while weight gain (>3BMI units) increased the risk of pre-eclampsia, gestational hypertension, emergency caesarean section, placental oversize and large for gestational age (LGA) birth at the second pregnancy. The relationship between weight gain and pre-eclampsia risk was evident in women who were overweight at first pregnancy only (BMI ≥25 units), while that between weight loss and preterm delivery was confined to women with a healthy weight at first pregnancy (BMI <25 units). In contrast, the association between weight loss and SGA was independent of first pregnancy BMI. A higher percentage of women who were obese at first pregnancy were likely to experience a large weight gain (P < 0.01) or weight loss (P < 0.001) between consecutive pregnancies compared with the normal BMI reference group. CONCLUSION: Inter-pregnancy weight change in either direction increases the risk of a number of contrasting pregnancy complications, including extremes of placental weight. The placenta may lie on the causal pathway between BMI change and the risk of LGA or SGA birth.

Fetoplacental biometry and umbilical artery Doppler velocimetry in the overnourished adolescent model of fetal growth restriction.

OBJECTIVE: The purpose of this study was to evaluate ultrasonographically fetal growth trajectories, placental biometry, and umbilical artery (UA) Doppler indices in growth-restricted pregnancies of overnourished adolescent ewes and normally developing pregnancies of control-fed ewes. STUDY DESIGN: Singleton pregnancies were established using embryo transfer in 42 adolescent ewes that were overnourished (n = 27) or control-fed (n = 15) and were scanned at weekly intervals from 83-126 days' gestation and necropsied at 131 days' gestation (term = 145 days). RESULTS: Ultrasonographic placental measurements were reduced and UA Doppler indices were increased from 83 days' gestation; measurements of fetal abdominal circumference and femur length, renal volume and tibia length, and biparietal diameter were reduced from 98, 105, and 112 days' gestation, respectively, in overnourished vs control-intake pregnancies. CONCLUSION: Overnourishment of adolescent sheep dams produced late-onset asymmetric fetal growth restriction that was commensurate with brain sparing. Ultrasonographic placental biometry was already reduced and UA Doppler indices increased by mid gestation in overnourished pregnancies, preceding reduced fetal growth velocity and indicating an early nutritionally mediated insult on placental development.

Adverse metabolic phenotype in low-birth-weight lambs and its modification by postnatal nutrition.

Both high and low maternal dietary intakes adversely affect fetal nutrient supply in adolescent sheep pregnancies. Aims were: (a) to assess the impact of prenatal nutrition on pregnancy outcome, offspring growth and offspring glucose metabolism and (b) to determine whether the offspring metabolic phenotype could then be altered by modifying postnatal nutrition. Dams carrying a single fetus were offered either an optimal control (C) intake to maintain adiposity throughout pregnancy, undernourished to maintain weight at conception but deplete maternal reserves (UN), or overnourished to promote rapid maternal growth and adiposity (ON). Placental weight and gestation length were reduced in ON dams and lamb birth weights were C>UN>ON (P < 0·001). All offspring were fed ad libitum from weaning to 6 months of age. ON offspring exhibited rapid catch-up growth and had increased fasting glucose and relative glucose intolerance compared with C offspring (P < 0·05). Irrespective of prenatal diet and sex, birth weight correlated negatively with these indices of glucose metabolism. From 7 to 12 months offspring either had continued ad libitum diet (ADLIB; to induce an obesogenic state) or a decreased ration appropriate for normal growth (NORM). At 12 months, the negative relationship between birth weight and indices of glucose metabolism persisted in ADLIB females (for example, fasting glucose, r - 0·632; P < 0·03) but was absent in NORM females and in both male groups. Therefore, low-birth-weight offspring from differentially achieved prenatal malnutrition exhibit an early adverse metabolic phenotype, and this can apparently be ameliorated by postnatal nutrition in females but not in males.

Postnatal hypothalamic-pituitary-adrenal function in sheep is influenced by age and sex, but not by prenatal growth restriction.

The relationship between impaired fetal nutrient supply and postnatal hypothalamic-pituitary-adrenal (HPA) function was examined in ovine models of prenatal growth restriction (GR) caused by small placental size (SP) or by maternal undernutrition (UN). Adrenocorticotrophin (ACTH) and cortisol responses following corticotrophin-releasing hormone (CRH) plus arginine vasopressin (AVP) challenge were examined at 9, 18 and 24 months in growth-restricted (GR-SP) and normal birthweight (control) females (Experiment 1), and at 6 months in growth-restricted (GR-SP, GR-UN) and normal weight males and females (Experiment 2). In Experiment 1, GR-SP offspring were born early, were 40% lighter at birth and had higher fractional weight gains to weaning than control offspring. Baseline ACTH and cortisol were independent of GR and cortisol decreased with age. GR did not affect the HPA response to CRH+AVP challenge at any stage, but ACTH increased with age. In Experiment 2, birthweight was greater in control offspring than in GR-UN offspring, which had a higher birthweight again compared with GR-SP offspring. Only the latter group was born early and exhibited rapid catch-up growth to weaning. Neither nutritional route to GR altered HPA function at 6 months. Males grew faster than females and HPA responses after stimulation were lower in males. Together, the results of these studies demonstrate that postnatal HPA function in sheep is influenced by age and sex, but not by GR.

Perinatal complications and maximising lamb survival in an adolescent paradigm characterised by premature delivery and low birthweight.

The competition for nutrients in overnourished and still-growing adolescent sheep negatively impacts gestation length, colostrum supply and lamb birthweight, all of which may affect neonatal morbidity and survival to weaning. Herein perinatal complications and the requirement for supplementary feeding were analysed in relation to gestational-intake, and the degree of premature delivery and prenatal growth-restriction exhibited. Pregnancies were established by embryo transfer and the mean/standard deviation (SD) gestation length and birthweight of the optimally-fed control group (n = 100) was used to define early delivery and reduced birthweight categories (1.5 and 3.0 SDs below the control mean for each aspect). Control lambs were largely delivered at term (94%), and had a normal birthweight (92%), while very preterm (≤139days, 18.5%) and preterm delivery (140-142days, 54.8%), extremely low birthweight (ELBW; females ≤2838g and males ≤3216g, 21.1%) and low birthweight (LBW; females 2839 to ≤4001g and males 3217 to ≤4372g, 32.2%), were common in the overnourished group (n = 270, P<0.001). Accordingly, overnourished dams were more likely to lamb without assistance while the incidence of major dystocia was greater in controls. Initial lamb vigour at birth was independent of gestational-intake, delivery or birthweight category but both ELBW and very premature lambs required more assistance with feeding in the first 24h postnatal, primarily reflecting low colostrum availability. Indeed, relative to normal, ELBW lambs had a greater risk of experiencing mismothering, and enhanced likelihood of requiring supplementary feeding throughout the neonatal period (P<0.001). ELBW lambs also had a greater possibility of respiratory issues at birth (P<0.01) and renal complications (P<0.001), while very preterm delivery was associated with an increased risk of gastrointestinal tract problems (P<0.01). In spite of these complications, all-cause mortality was low (5.4%) suggesting that our proactive neonatal care regime can overcome many of the issues associated with extreme prematurity and low birthweight.

Effect of weight and adiposity at conception and wide variations in gestational dietary intake on pregnancy outcome and early postnatal performance in young adolescent sheep.

Nutritional backgrounds prior to pregnancy may interact with subsequent gestational intake to influence pregnancy outcome, particularly in young, growing adolescents. To investigate this interaction, singleton pregnancies were established in two groups of adolescent sheep of identical age but different initial weight and adiposity score, classified as good (G) and poor (P) body mass index (BMI). Thereafter, ewes were offered either an optimal control (C) intake to maintain adiposity throughout pregnancy, undernourished (UN) to maintain weight at conception but deplete maternal body reserves, or overnourished (ON) to promote rapid maternal growth and adiposity, resulting in a 2 x 3 factorial design. Gestation length was independent of BMI and reduced in ON dams. Average placental and lamb birth weights were influenced by initial BMI (G > P) and gestational intake (C > UN > ON), with the highest incidence of growth restriction in ON groups. Metabolic challenges at two thirds of gestation revealed enhanced insulin insensitivity in ON dams (higher glucose postinsulin challenge and higher insulin postglucose challenge), but nevertheless fetal growth was constrained. Initial colostrum yield, total IgG, and nutrient supply were reduced in ON groups, but these low-birth-weight lambs exhibited rapid catch-up growth to weaning. Thus, both maternal BMI at conception and gestational intake have a profound influence on pregnancy outcome in young, putatively growing adolescent sheep and may have implications for the nutritional management of pregnant adolescent humans.

A new customised placental weight standard redefines the relationship between maternal obesity and extremes of placental size and is more closely associated with pregnancy complications than an existing population standard.

Placental weight is a valuable indicator of its function, predicting both pregnancy outcome and lifelong health. Population-based centile charts of weight-for-gestational-age and parity are useful for identifying extremes of placental weight but fail to consider maternal size. To address this deficit, a multiple regression model was fitted to derive coefficients for predicting normal placental weight using records from healthy pregnancies of nulliparous/multiparous women of differing height and weight (n = 107,170 deliveries, 37-43 weeks gestation). The difference between actual and predicted placental weight generated a z-score/individual centile for the entire cohort including women with pregnancy complications (n = 121,591). The association between maternal BMI and placental weight extremes defined by the new customised versus population-based standard was investigated by logistic regression, as was the association between low placental weight and pregnancy complications. Underweight women had a greater risk of low placental weight [<10thcentile, OR 1.84 (95% CI 1.66, 2.05)] and obese women had a greater risk of high placental weight [>90th centile, OR 1.98 (95% CI 1.88, 2.10)] using a population standard. After customisation, the risk of high placental weight in obese/morbidly obese women was attenuated [OR 1.17 (95% CI 1.09, 1.25)]/no longer significant, while their risk of low placental weight was 59%-129% higher (P < 0.001). The customised placental weight standard was more closely associated with stillbirth, hypertensive disease, placental abruption and neonatal death than the population standard. Our customised placental weight standard reveals higher risk of relative placental growth restriction leading to lower than expected birthweights in obese women, and a stronger association between low placental weight and pregnancy complications generally. Further, it provides an alternative tool for defining placental weight extremes with implications for the placental programming of chronic disease.

Ovine prenatal growth-restriction and sex influence fetal adipose tissue phenotype and impact postnatal lipid metabolism and adiposity in vivo from birth until adulthood.

Adipose tissue development begins in utero and is a key target of developmental programming. Here the influence of nutritionally-mediated prenatal growth-restriction on perirenal adipose tissue (PAT) gene expression and adipocyte phenotype in late fetal life was investigated in both sexes in an ovine model. Likewise circulating leptin concentrations and non-esterified fatty acid (NEFA) and glycerol responses to glucose challenge were determined in relation to offspring adiposity at key stages from birth to mid-adult life. In both studies' singleton-bearing adolescent sheep were fed control or high nutrient intakes to induce normal or growth-restricted pregnancies, respectively. Fetal growth-restriction at day 130 of gestation (32% lighter) was characterised by greater body-weight-specific PAT mass and higher PAT expression of peroxisome proliferator-activated receptor gamma (PPARɤ), glycerol-3-phosphate dehydrogenase, hormone sensitive lipase (HSL), insulin-like growth factor 1 receptor, and uncoupling protein 1. Independent of prenatal growth, females had a greater body-weight-specific PAT mass, more multilocular adipocytes, higher leptin and lower insulin-like growth factor 1 mRNA than males. Growth-restricted offspring of both sexes (42% lighter at birth) were characterised by higher plasma NEFA concentrations across the life-course (post-fasting and after glucose challenge at 7, 32, 60, 85 and 106 weeks of age) consistent with reduced adipose tissue insulin sensitivity. Circulating plasma leptin correlated with body fat percentage (females>males) and restricted compared with normal females had more body fat and increased abundance of PPARɤ, HSL, leptin and adiponectin mRNA in PAT at necropsy (109 weeks). Therefore, prenatal nutrient supply and sex both influence adipose tissue development with consequences for lipid metabolism and body composition persisting throughout the life-course.

Fetoplacental growth and vascular development in overnourished adolescent sheep at day 50, 90 and 130 of gestation.

To establish the basis for altered placental development and function previously observed at late gestation, fetoplacental growth and placental vascular development were measured at three stages of gestation in a nutritional paradigm of compromised pregnancy. Singleton pregnancies to a single sire were established and thereafter adolescent ewes were offered an optimal control (C) or a high (H) dietary intake. At day 50, the H group had elevated maternal insulin and amniotic glucose, whereas mass of the fetus and placenta were unaltered. At day 90, the H group exhibited elevated maternal insulin, IGF1 and glucose; fetal weight and glucose concentrations in H were increased relative to C, but placental weight was independent of nutrition. By day 130, total placentome weight in the H group was reduced by 46% and was associated with lower fetal glucose and a 20% reduction in fetal weight. As pregnancy progressed from day 50 to 130, the parameters of vascular development in the maternal and fetal components of the placenta increased. In the fetal cotyledon, high dietary intakes were associated with impaired vascular development at day 50 and an increase in capillary number at day 90. At day 130, all vascular indices were independent of nutrition. Thus, high dietary intakes to promote rapid maternal growth influence capillary development in the fetal portion of the placenta during early to mid-pregnancy and may underlie the subsequent reduction in placental mass and hence fetal nutrient supply observed during the final third of gestation.

Competition for nutrients in pregnant adolescents: consequences for maternal, conceptus and offspring endocrine systems.

The competition for nutrients that arises when pregnancy coincides with continuing or incomplete growth in young adolescent girls increases the risk of preterm delivery and low birthweight with negative after-effects for mother and child extending beyond the perinatal period. Sheep paradigms involving nutritional management of weight and adiposity in young, biologically immature adolescents have allowed the consequences of differential maternal growth status to be explored. Although nutrient reserves at conception play a modest role, it is the dietary manipulation of the maternal growth trajectory thereafter which has the most negative impact on pregnancy outcome. Overnourishing adolescents to promote rapid maternal growth is particularly detrimental as placental growth, uteroplacental blood flows and fetal nutrient delivery are perturbed leading to a high incidence of fetal growth restriction and premature delivery of low birthweight lambs, whereas in undernourished adolescents further maternal growth is prevented, and depletion of the maternal body results in a small reduction in birthweight independent of placental size. Maternal and placental endocrine systems are differentially altered in both paradigms with downstream effects on fetal endocrine systems, organ development and body composition. Approaches to reverse these effects have been explored, predominantly targeting placental growth or function. After birth, growth-restricted offspring born to overnourished adolescents and fed to appetite have an altered metabolic phenotype which persists into adulthood, whereas offspring of undernourished adolescents are largely unaffected. This body of work using ovine paradigms has public health implications for nutritional advice offered to young adolescents before and during pregnancy, and their offspring thereafter.

An immunohistochemical study of the localization and developmental expression of ghrelin and its functional receptor in the ovine placenta.

BACKGROUND: Ghrelin is an orexigenic hormone principally produced by the stomach, but also by numerous peripheral tissues including the placenta. Ghrelin acts via growth hormone secretagogue receptors (GHSR-1a) to alter food intake, fat utilization, and cellular proliferation, and has been suggested to play a role in the developmental growth of the fetoplacental unit. The placental expression of ghrelin and its role in ruminant species is not known. We tested the hypotheses that ghrelin and its functional receptor, GHSR-1a, are present in tissues of the ovine placenta, and that their expression is linked to the stage of development. METHODS: Antibodies raised against ghrelin and GHSR-1a were used in standard immunohistochemical protocols on placental tissues collected from pregnant ewes (n = 6 per gestational time point) at days 50, 80, 100, 128 and 135 of gestation (term approximately day 145). Immunostaining for ghrelin and GHSR-1a was quantified using computer-aided image analysis. Image analysis data were subjected to one-way ANOVA, with differences in immunostaining between time-points determined by Fisher's least significant difference. RESULTS: Positive immunostaining for ghrelin was detected in ovine placentae at all gestational time points, with staining localized to the maternal epithelium, caruncle and trophectoderm. There was a significant effect of gestational age (p < 0.001) on the placental expression of ghrelin, with maximal levels at gestational day 80. GHSR-1a immunostaining was detected in the fetal trophectoderm at all time points. In contrast to the gestational pattern of ghrelin expression, there was no effect of gestational age on placental GHSR-1a immunoexpression. CONCLUSION: Ghrelin and GHSR-1a are both present in the ovine placenta, and ghrelin displays a developmentally-related pattern of expression. Therefore, these data strongly suggest that the ghrelin system may have a role in feto-placental development in sheep.

Weight change across the start of three consecutive pregnancies and the risk of maternal morbidity and SGA birth at the second and third pregnancy.

BACKGROUND: Weight-change across parities and/or current BMI may influence maternal and fetal morbidity and requires to be differentiated to better inform weight-management guidance. METHODS: Direction, pattern and magnitude of weight-change across three consecutive parities and thereby two inter-pregnancy periods was described in 5079 women. The association between inter-pregnancy weight-change versus current BMI and adverse maternal events, SGA-birth and preterm delivery at second and third pregnancy were investigated by logistic regression. RESULTS: More women gained weight across the defined childbearing period than lost it, with ~35% of normal and overweight women gaining sufficient weight to move up a BMI-category. Nine patterns of weight-change were defined across two inter-pregnancy periods and 50% of women remained weight-stable throughout (within 2BMI units/period). Women who were overweight/obese at first pregnancy had higher risk of substantial weight-gain and loss (>10kg) during each of two inter-pregnancy periods. Inter-pregnancy weight-gain (> 2BMI units) between first and second pregnancy increased the risk of maternal morbidity (1or more event of hypertensive disease, caesarean-section, thromboembolism) at second pregnancy, while weight-loss (>2BMI units) increased the risk of SGA-birth. Similarly, increased risk of maternal morbidity at the third pregnancy was influenced by weight-gain during both inter-pregnancy periods but not by current BMI-category. Both weight-gain between first and second pregnancy, and being overweight/obese by third pregnancy protected the fetus against SGA-birth whereas weight-loss between second and third pregnancy doubled the SGA risk. CONCLUSION: Half the women studied exhibited significant weight-fluctuations. This influenced their risk of maternal morbidity and SGA-birth at second and third pregnancy.

Overnourishing pregnant adolescent ewes preserves perirenal fat deposition in their growth-restricted fetuses.

Overnourishing the adolescent sheep promotes rapid maternal growth at the expense of the gravid uterus. The growth of the placenta is impaired and results in the premature delivery of low-birthweight lambs. The present study details fetal adipose tissue development in these growth-restricted pregnancies. Singleton pregnancies were established by embryo transfer and, thereafter, adolescent ewes were offered a high (H; n = 12) or moderate (M; n = 14) level of a complete diet until necropsy on Day 131 of gestation. Fetal weight was lower (P < 0.001) in H compared with M groups. High maternal intake preserved brain and perirenal fat weight (P < 0.003), whereas relative weights of the heart, lungs, spleen and liver were unaltered. High nutrient intake resulted in significantly elevated maternal plasma concentrations of insulin, leptin, prolactin and glucose, no significant changes in fetal insulin, leptin or non-esterified fatty acids and attenuated fetal prolactin concentrations. Irrespective of nutritional intake, maternal plasma leptin, prolactin and glucose concentrations were negatively correlated with fetal weight and were positively correlated with fetal perirenal fat proportion (all P < 0.01). The mRNA expression for leptin, prolactin receptor and uncoupling protein (UCP) 1 in fetal perirenal fat was equivalent between groups, but, irrespective of maternal nutrition, UCP1 mRNA levels were negatively correlated with fetal weight (P < 0.01). Thus, overnourishing pregnant adolescent sheep preserves fat deposition in their growth-restricted fetuses, which may have implications for neonatal thermogenesis and for programming of postnatal adiposity.

Inter-Pregnancy Weight Change and the Risk of Recurrent Pregnancy Complications.

Women with specific adverse pregnancy outcomes in their first pregnancy may be receptive to inter-pregnancy weight management guidance aimed at preventing these complications reoccurring in subsequent pregnancies. Thus the association between inter-pregnancy weight change and the risk of recurrent pregnancy complications at the second pregnancy was investigated in a retrospective cohort study of 24,520 women with their first-ever and second consecutive deliveries in Aberdeen using logistic regression. Compared with women who were weight stable, weight loss (>2BMI units) between pregnancies was associated with an increased risk of recurrent small for gestational age (SGA) birth and elective Cesarean-section, and was protective against recurrent pre-eclampsia, placental oversize and large for gestational age (LGA) birth. Conversely weight gain (>2BMI units) between pregnancies increased the risk of recurrent gestational hypertension, placental oversize and LGA birth and was protective against recurrent low placental weight and SGA birth. The relationships between weight gain, and placental and birth weight extremes were evident only in women with a healthy weight at first pregnancy (BMI<25units), while that between weight gain and the increased risk of recurrent gestational hypertension was largely independent of first pregnancy BMI. No relationship was detected between inter-pregnancy weight change and the risk of recurrent spontaneous preterm delivery, labour induction, instrumental delivery, emergency Cesarean-section or postpartum hemorrhage. Therefor inter-pregnancy weight change impacts the risk of recurrent hypertensive disorders, SGA and LGA birth and women with a prior history of these specific conditions may benefit from targeted nutritional advice to either lose or gain weight after their first pregnancy.

Placental vascularity and markers of angiogenesis in relation to prenatal growth status in overnourished adolescent ewes.

INTRODUCTION: Placental vascularity may be important in the development of fetal growth restriction (FGR). The overnourished adolescent ewe is a robust model of the condition, with ∼50% of offspring demonstrating FGR (birthweight >2 standard deviations below optimally-fed control mean). We studied whether placental vascularity, angiogenesis and glucose transport reflect FGR severity. METHODS: Singleton pregnancies were established in adolescent ewes either overnourished to putatively restrict fetoplacental growth (n = 27) or control-fed (n = 12). At 131d (term = 145d) pregnancies were interrupted and fetuses classified as FGR (n = 17, <4222 g, -2SD below control-fed mean) or non-FGR (n = 10). Placentome capillary area density (CAD), number density (CND), surface density (CSD), and area per capillary (APC) in the fetal cotyledon (COT) and maternal caruncle (CAR) were analysed using immunostaining. COT/CAR mRNA expression of angiogenic ligands/receptors and glucose transporters were measured by qRT-PCR. RESULTS: Fetal weight was reduced in FGR vs. Non-FGR/Control groups. Total placentome weight was Control > Non-FGR > FGR and fetal:placental weight ratios were higher in overnourished versus Control groups. COT vascular indices were Non-FGR > FGR > Control. COT-CAD, CSD and APC were significantly greater in Non-FGR overnourished versus Control and intermediate in FGR groups. CAR vascularity did not differ. CAR-VEGFA/FLT1/KDR/ANGPT1/ANGPT2/SLC2A1/SLC2A3 mRNA was lower and COT-ANGPT2 higher in overnourished versus Control groups. DISCUSSION: Relative to control-intake pregnancy, overnourished pregnancies are characterised by higher COT vascularity, potentially a compensatory response to reduced nutrient supply, reflected by higher fetal:placental weight ratios. Compared with overnourished pregnancies where fetal growth is relatively preserved, overnourished pregnancies culminating in marked FGR have less placental vascularity, suggesting incomplete adaptation to the prenatal insult.