Dietary protein during gestation affects placental development in heifers

The influence of nutritional protein during the first and second trimesters of pregnancy on placental measures at term and caruncle numbers in the uteri of adult offspring was determined in composite beef heifers. At artificial insemination (AI), heifers were divided by weight and composite genotype into four dietary treatment groups, identified by the level of protein components fed during the first and second trimesters: high/high (HH), high/low (HL), low/high (LH), low/low (LL). Expelled placentas were collected and weighed, and cotyledons were dissected, counted, weighed, and measured. Uteri from mature female offspring were dissected at slaughter and caruncles counted. The number of cotyledons in the expelled placenta was increased by high dietary protein in the second trimester (P = 0.02) and varied with genotype (P = 0.03). Placental weight was influenced by maternal undernutrition during early gestation dependent on dam genotype (P = 0.001). Placental efficiency, as determined by calf weight:placental weight, increased with dam age (P = 0.03). Calf birth weight was closely associated with placental weight (P = 0.002) and cotyledonary weight (P = 0.001) and surface area (P = 0.04), but not with the number of cotyledons. Leptin concentrations during early (R = -0.29) and late gestation (R = -0.25) correlated with placental weight, and Insulin-like growth factor binding proteins throughout gestation correlated with the number of cotyledons (R = -0.28 to-0.33). The number of uterine caruncles in the nonpregnant adult offspring did not correlate with the dam's genotype, nutrition treatment, or cotyledon number in the expelled placenta.     

Maternal nutrition in early and late pregnancy in relation to placental and fetal growth.

OBJECTIVE: To assess how nutrient intakes of mothers in early and late pregnancy influence placental and fetal growth. DESIGN: Prospective observational study. SETTING: Princess Anne Maternity Hospital, Southampton. SUBJECTS: 538 mothers who delivered at term. MAIN OUTCOME MEASURES: Placental and birth weights adjusted for the infant''s sex and duration of gestation. RESULTS: Mothers who had high carbohydrate intakes in early pregnancy had babies with lower placental and birth weights. Low maternal intakes of dairy and meat protein in late pregnancy were also associated with lower placental and birth weights. Placental weight fell by 49 g(95% confidence interval 16 g to 81 g; P=0.002) for each log g increase in intake of carbohydrate in early pregnancy and by 1.4 g (0.4 g to 2.4 g; P=0.005) for each g decrease in intake of dairy protein in late pregnancy. Birth weight fell by 165 g (49 g to 282 g; P=0.005) for each log g increase in carbohydrate intake in early pregnancy and by 3.1 g (0.3 g to 6.0 g; P=0.03) for each g decrease in meat protein intake in late pregnancy. These associations were independent of the mother''s height and body mass index and of strong relations between the mother''s birth weight and the placental and birth weights of her offspring. CONCLUSION: These findings suggest that a high carbohydrate intake in early pregnancy suppresses placental growth, especially if combined with a low dairy protein intake in late pregnancy. Such an effect could have long term consequences for the offspring''s risk of cardiovascular disease.     

Influence of maternal nutrition on outcome of pregnancy: prospective cohort study

ObjectiveTo investigate the relations of maternal diet and smoking during pregnancy to placental and birth weights at term.DesignProspective cohort study.SettingDistrict general hospital in the south of England.Participants693 pregnant nulliparous white women with singleton pregnancies who were selected from antenatal booking clinics with stratified random sampling.ResultsPlacental and birth weights were unrelated to the intake of any macronutrient. Early in pregnancy, vitamin C was the only micronutrient independently associated with birth weight after adjustment for maternal height and smoking. Each ln mg increase in vitamin C was associated with a 50.8 g (95% confidence interval 4.6 g to 97.0 g) increase in birth weight. Vitamin C, vitamin E, and folate were each associated with placental weight after adjustment for maternal characteristics. In simultaneous regression, however, vitamin C was the only nutrient predictive of placental weight: each ln mg increase in vitamin C was associated with a 3.2% (0.4 to 6.1) rise in placental weight. No nutrient late in pregnancy was associated with either placental or birth weight.ConclusionsConcern over the impact of maternal nutrition on the health of the infant has been premature. Maternal nutrition, at least in industrialised populations, seems to have only a small effect on placental and birth weights. Other possible determinants of fetal and placental growth should be investigated.

Key messages

• Placental and infant birth weights were not associated with the intake of any macronutrient early or later in pregnancy
• After adjustment for the effects of maternal height and smoking, only vitamin C independently predicted birth weight. The expected mean difference in birth weight for infants with mothers in the upper and lower thirds of intake was about 70 g
• Vitamin C was the only nutrient that independently predicted placental weight, but again this relation was of doubtful clinical significance
• Among relatively well nourished women in industrialised countries, maternal nutrition seems to have only a marginal impact on infant and placental size. Other causes of variation in the size of clinically normal infants should now be investigated

     

Placental growth patterns affect birth weight for given placental weight

BACKGROUND: An important contributor to fetal growth is growth of the placenta, the fetus' sole source of nutrients and oxygen. Here we use placental growth measures (larger and smaller disk diameters, reflecting the laterally expanding chorionic plate, and disk thickness) to test the hypothesis that placental growth patterns, while associated with placental weight and birth weight, measure placental functional efficiency, and will have independent effects on the feto-placental weight ratio (FPR). METHODS: Placental measures were available from 23,313 participants in the Collaborative Perinatal Project delivered between 34 and 43 completed weeks. Continuous variables were analyzed by regression for associations with placental weight, birth weight, and FPR, to further explore effects of placental growth patterns on the FPR (lateral chorionic plate growth and chorionic disk thickness were grouped as low, normal, and high values). The relationships of the nine resultant combinations of placental growth categories to the FPR using birth weight adjusted for gestational age, infant gender, parity, and African American race were analyzed (ANOVA). RESULTS: As chorionic disk area and thickness increased, birth weight and placental weight increased, and the FPR decreased (each p < .0001) after adjustment for gestational age, parity, race, and infant gender. Small, thin placental disks had an adjusted FPR of 8.46; the largest, thickest placentas had an adjusted FPR of 6.33. The nine categories of FPRs were significantly different, consistent with chorionic plate area and disk thickness combining to determine the FPR. CONCLUSIONS: Patterns of placental growth, relating to different functional dimensions of the placenta, deliver a different birth weight for a given placental weight.     

Effects of dietary enrichment with a marine oil-based n-3 LCPUFA supplement in sows with predicted birth weight phenotypes on birth litter quality and growth performance to weaning

The effects of a marine oil-based n-3 long-chain polyunsaturated fatty acid (mLCPUFA) supplement fed to the sow from weaning, through the rebreeding period, during gestation and until end of lactation on litter characteristics from birth until weaning were studied in sows with known litter birth weight phenotypes. It was hypothesized that low birth weight (LBW) litters would benefit more from mLCPUFA supplementation than high birth weight litters. A total of 163 sows (mean parity=4.9±0.9) were rebred after weaning. Sows were pair-matched by parity and litter average birth weight of the previous three litters. Within pairs, sows were allocated to be fed either standard corn/soyabean meal-based gestation and lactation diets (CON), or the same diets enriched with 0.5% of the mLCPUFA supplement at the expense of corn. Each litter between 9 and 16 total pigs born was classified as LBW or medium/high average birth weight (MHBW) litter and there was a significant correlation (P<0.001) between litter average birth weight of the current and previous litters within sows (r=0.49). Sow serum was harvested at day 113 of gestation for determination of immunoglobulin G (IgG) concentrations. The number of pigs born total and alive were lower (P=0.01) in mLCPUFA than CON sows, whereas the number of stillborn and mummified pigs were similar between treatments. Number of stillborns (trend) and mummies (P<0.01) were higher in LBW than MHBW litters. Tissue weights and brain : tissue weight ratios were similar between treatments, but LBW litters had decreased tissue weights and increased brain : tissue weight ratios compared with MHBW litters. Placental weight was lower (P=0.01) in LBW than MHBW litters, but was not different between treatments. Average and total litter weight at day 1 was similar between treatments. mLCPUFA increased weaning weight (P=0.08) and average daily gain (P<0.05) in MHBW litters, but not in LBW litters. Pre-weaning mortality was similar between treatments, but was higher (P<0.01) in LBW than MHBW litters. IgG concentration in sow serum was similar between treatments and litter birth weight categories. In conclusion, litter birth weight phenotype was repeatable within sows and LBW litters showed the benchmarks of intra-uterine growth retardation (lower placental weight and brain sparing effects). As maternal mLCPUFA supplementation decreased litter size overall, only improved litter growth rate until weaning in MHBW litters, and did not affect pre-weaning mortality, maternal mLCPUFA supplementation was not an effective strategy in our study for mitigating negative effects of a LBW litter phenotype.     

Metals content in placentas from moderate cigarette consumers: correlation with newborn birth weight

Cigarette consumption during pregnancy produces deleterious effects in both, mother and fetus, some of them due to the presence of toxic elements in cigarette smoke, such as cadmium. Placenta constitutes a dual-purpose specimen for evaluating the pollutant burden exerted on the mother as well as on the fetus. The main objective of this study was to establish a correlation between placental concentration and distribution of some metal elements and birth weight of neonates delivered by mothers, who were either moderate smokers or nonsmokers. Forty nonsmoking and moderate smoking pregnant women paired per age, parity, weight, height and body mass index were selected. Smoking was assessed by self-reported cigarette consumption during pregnancy and urine cotinine concentration before delivery. Placental metal concentrations were evaluated by atomic absorption spectrometry (copper and cadmium) and neutron activation analysis (zinc and iron). Newborns from smokers had lower birth weights compared to infants from nonsmokers. Birth weights were correlated with placental cadmium concentrations in both, smokers and nonsmokers. Placental zinc and cadmium of smokers were mainly located at the maternal side and their levels were higher than those found in nonsmokers placentas. In addition, all metal nutrient/pollutant ratios were decreased in the smoker group. In this first study performed in our region, we found that moderate smoking mothers deliver neonates with decreased birth weight and highly correlated to placental cadmium concentration. Decreased metal nutrient/pollutant ratios, a condition here found in smokers, may indicate a placental dysfunction, contributing to impair birth weight.     

Birth weight from pregnancies dated by ultrasonography in a multicultural British population.

OBJECTIVE--To produce standard curves of birth weight according to gestational age validated by ultrasonography in the British population, with particular reference to the effects of ethnic origin. DESIGN--Retrospective analysis of computerised obstetric database. SETTING--Three large maternity units associated with Nottingham University with over 16,000 deliveries a year. PATIENTS--41,718 women with ultrasound dated singleton pregnancies and delivery between 168 and 300 days'' gestation. MAIN OUTCOME MEASURES--Length of gestation, ethnic origin, parity, maternal height and weight at booking, smoking during pregnancy; the effect of these variables on birth weight. RESULTS--Birth weights from ultrasound dated pregnancies have a higher population mean and show less flattening of the birthweight curve at term than those of pregnancies dated from menstrual history. Significant differences were observed in mean birth weights of babies of mothers of European origin (3357 g), of Afro-Caribbean origin (3173 g), and from the Indian subcontinent (3096 g). There were also significant interethnic differences in length of gestation, parity, maternal height, booking weight, and smoking habit which affected birth weight. The ethnic differences in birth weight were even greater when the effect of smoking was excluded. CONCLUSIONS--Birthweight standards require precise dating of pregnancy and should describe the population from which they were derived. In a heterogeneous maternity population the accurate assessment of an individual baby''s weight needs to take the factors which affect birthweight standards into consideration.     

Relationship between placental vascular endothelial growth factor expression and placental/endometrial vascularity in the pig

We investigated the temporal association between placental vascular endothelial growth factor (VEGF), a potent stimulator of angiogenesis and vascular permeability, and changes in placental/endometrial vascularity on selected days throughout gestation in the pig. Placental and endometrial tissues were collected from sows on Days 25 (n = 4), 36 (n =6), 44 (n = 6), 70 (n =5), 90 (n =5 ), and 112 (n = 7) of gestation. Cross sections of the placental/endometrial interface of each conceptus were used to estimate the number of blood vessels per unit area via image analysis and the intensity of VEGF staining via immunohistochemistry. Placental tissues were also collected on these days to evaluate VEGF mRNA expression. Placental VEGF mRNA expression and the numbers of blood vessels per unit area of placental and adjacent endometrial tissue were low and decreasing from Day 25 to Day 44, before increasing (P < 0.05) markedly and progressively through Day 112. These data are consistent with the marked increase in VEGF immunostaining in the chorionic and uterine luminal epithelium from early to late gestation. Further, these increases in placental VEGF mRNA were positively correlated with fetal weight (r = 0.73; P < 0.0001) and placental efficiency (fetal weight/placental weight ratio; r = 0.66, P < 0.0001). These data are consistent with a role for VEGF in increasing the number of blood vessels at the placental endometrial interface, resulting in an increased capacity for nutrient transfer from the maternal to the fetal compartment.     

Prospective cohort study of factors influencing the relative weights of the placenta and the newborn infant.

OBJECTIVES: To determine the demographic, environmental, and medical factors that influence the relative weights of the newborn infant and the placenta and compare this ratio with other factors known to predispose to adult ill health. DESIGN: Prospective cohort study. SETTING: The tertiary referral centre for perinatal care in Perth, Western Australia. SUBJECTS: 2507 pregnant women who delivered a single live infant at term. MAIN OUTCOME MEASURES: Placental weight, birth weight, and the ratio of placental weight to birth weight. RESULTS: By multiple regression analysis the placental weight to birthweight ratio was significantly and positively associated with gestational age, female sex, Asian parentage, increasing maternal body mass index, increased maternal weight at booking, lower socioeconomic status, maternal anaemia, and increasing number of cigarettes smoked daily. There were no consistent relations between the placental weight to birthweight ratio and measures of newborn size. CONCLUSIONS: The ratio of placental weight to birth weight is not an accurate marker of fetal growth. In its role as a predictor of adult disease the ratio may be acting as a surrogate for other factors which are already known to influence health and may act before or after birth. Determining the role that relative growth rates of the fetus and placenta have in predisposing to adult disease requires prospective study to account for the many confounding variables which complicate this hypothesis.     

Sexually dimorphic effects of maternal alcohol intake and adrenalectomy on left ventricular hypertrophy in rat offspring

In humans, low birth weight and increased placental weight can be associated with cardiovascular disease in adulthood. Low birth weight and increased placental size are known to occur after fetal alcohol exposure or prenatal glucocorticoid administration. Thus the effects of removing the alcohol-induced increase in maternal corticosterone by maternal adrenalectomy on predictors of cardiovascular disease in adulthood were examined in rats. Alcohol exposure of dams during the last 2 wk of gestation resulted in significantly decreased fetal weight and increased placental weight on gestational day 21. Adult female, but not male, offspring of alcohol-consuming mothers exhibited left ventricular hypertrophy. Placental 11beta-hydroxysteroid dehydrogenase-2 (11beta-HSD-2) mRNA levels, measured by Northern blot, were decreased in females but not males. Adrenalectomy of alcohol-consuming dams reversed the increase in placental weight and the decrease in female placental 11beta-HSD-2 expression and eliminated the left ventricular hypertrophy of adult female offspring. These data suggest that alcohol-induced changes in placental 11beta-HSD-2 mRNA levels and left ventricular weight are coupled in female offspring only and depend on maternal adrenal status.     

Analyses of factors influencing the birth weight and neonatal growth rate of Cheetah (Acinonyx jubatus) cubs

Birth weight and the neonatal growth rate are reliable indicators of neonatal survival prospects. Data on weight at birth and consecutive weights until 40 days of age were recorded for cheetah cubs in 16 litters. Growth was found to be linear during the first 40 days of life. Weight data were used to evaluate the influence of several factors on birth weight and neonatal growth. The factors used in these analyses were sex, litter identity, litter size, average litter size over the first 40 days, birth weight, parents, gestation length, parity of the dam, and inbreeding. For birth weight and neonatal growth, litter identity was the major explanatory factor (81.8 and 85.3%). For birth weight, a significant influence of gestation length was found (p < 0.05), whereas inbreeding coefficient tended to decrease the birth weight (p = 0.09). Together, gestation length and inbreeding coefficient account for 57.5% of the between‐litter variation for birth weight. Factors with significant influences on neonatal growth are gestation length and parity (p < 0.05). The average litter size over the first 40 days tended to influence neonatal growth (p = 0.07). These three variables together account for 99.9% of the between‐litter variation for neonatal growth during the first 40 days of life. A comparison of neonatal growth between mother‐raised and hand‐raised cubs revealed a lower growth rate in hand‐raised cubs (45 vs. 27 g/day). Zoo Biol 18:129–139, 1999. © 1999 Wiley‐Liss, Inc.     

The relationship between plasma oestrone sulphate concentrations in pregnant dairy cattle and calf birth weight, calf viability, placental weight and placental expulsion

A total of 54 Holstein-Friesian cows (13 primiparous and 41 multiparous) was used to study maternal plasma oestrone sulphate (E1S) during pregnancy and its relationship to birth weight and viability of calves and time required for placental expulsion after calving. Plasma samples were obtained from the tail vein of cows once every month from days 90 to 180, every 2 weeks from days 181 to 270, and every day from day 270 of gestation to parturition. The E1S concentrations were measured by radioimmunoassay, and birth weight, placental measurements, neonatal viability and the period from calving to placental expulsion were recorded. E1S concentrations were correlated positively (0.71 > or = r > or = 0.32, P < 0.05 or P < 0.01) with calf birth weight and weights of cotyledons, intercotyledonary membranes and total placenta from days 210 of gestation to 1 day prepartum. Calf birth weight was correlated positively (p < 0.01) with the weight of the cotyledons (r = 0.87), intercotyledonary membranes (r = 0.78) and total placenta (r = 0.88). In addition, E1S concentrations were positively correlated (0.63 > or = r > or = 0.28, P < 0.05 or P < 0.01) with the neonatal viability after day 195 of pregnancy, and were negatively correlated (-0.29 > or = r > or = -0.55, P < 0.05 or P < 0.01) with the intervals from parturition to placental expulsion after 225 days of pregnancy. The results suggest that variation among dams for circulating E1S levels during late pregnancy may be caused by variation of placental development and ability for oestrogen production and conjugation, and they may influence fetal growth, neonatal viability and retained placenta.     

Effect of heat stress on ovine placental growth in early pregnancy.

Ditocous Dorset ewes were fed to predicted requirements and kept in environmental chambers at 21 degrees C (n = 6) or 40 degrees C (n = 5) between days 50 and 75 of gestation. Ewes were slaughtered and the pregnant uterus was dissected for measurement of conceptus weights and in vitro estimations of placental mitotic activity. Heat caused a 19% reduction in placental weight but did not affect fetal weight. Placental DNA and protein concentrations and protein/DNA were similar in both groups. Total placental DNA content was significantly reduced in the heated ewes, suggesting a reduction in cell number; however, DNA synthetic rate tended to be higher. These results are consistent with the hypothesis that fetal growth retardation in chronically heat-stressed ewes occurs in late pregnancy as a consequence of a primary reduction in placental growth in early gestation.     

Familial Trends in Low Birth Weight

The reproductive performance of sisters and sisters-in-law of 185 women who had delivered “light-for-dates” and “premature expulsion” low birth weight infants was studied. Percentile birth weights were compared taking into account length of gestation, fetal sex, and the height, weight, parity, and smoking habits of the mother. Sisters of women who had delivered light-for-dates babies had lighter babies than the general population, their sisters-in-law, or the sisters of women in the premature expulsion group. These other groups, however, had the expected distribution of percentile birth weights. Data on familial trends in smoking habits and unknown gestation are also presented. The results are consistent with the theory that the mother''s own intrauterine experience affects her reproductive performance but could also be explained by shared family learning experience of as yet unidentified microsocial factors related to pregnancy performance.     

Birth weight and birth rate of heavy calves conceived by transfer of in vitro or in vivo produced bovine embryos

The aim of this study was to evaluate the difference in birth weight and gestation length between Japanese Black calves obtained from transfer of bovine embryos produced in vitro (IVP) and those developed in vivo (IVD). An additional objective was to clarify the sire effect on birth weight and gestation length and to examine the birth rate of heavier calves. Two Japanese Black bulls breed at our experimental station were used as a semen source for production of IVP and IVD embryos. Thirty-eight Japanese Black heifers and cows of various genetic backgrounds were used as embryo donors for IVD embryos. Ovaries for IVP embryos were collected at random at a local slaughterhouse from Japanese Black cattle of various genetic backgrounds. IVP embryos were produced using co-culturing with cumulus cells in 5% CS+TCM 199. Both the IVD and IVP embryos were transferred non-surgically to Holstein recipients on day 7+/-1 of estrous cycle. In this study, the birth weights and gestation lengths of half-sib single calves for bull A and B were analyzed.The numbers of single calves born by transfer of IVP and IVD embryos for bull A and B were 133 and 121, 243 and 465, respectively. The birth weight of the IVP calves was significantly higher (P<0.01) than that of the IVD (bull A: 31.0+/-0.4 kg versus 27.2+/-0.4 kg and bull B: 29.9+/-0.6 kg versus 26.6+/-0.2 kg). Gestation length of the IVP calves for bull A was significantly longer (P<0.01) than that of the IVD (291.9+/-0.9 days versus 283.6+/-0.5 days). However, for bull B, there were no differences in gestation length between the IVP and IVD calves (285.9+/-0.7 days versus 286.2+/-0.3 days). These results clearly indicated that IVP calves had heavier birth weights than IVD calves but that the average gestation length of IVP calves was not always longer than that of IVD calves. Furthermore, the birth rate of heavier calves and the incidence of stillbirth and perinatal mortality up to 48 h post partum in IVP calves (bull A: 11.3%, bull B: 7.8%) were greater (P<0.05) than those in IVD calves from both bulls (bull A: 4.1%, bull B: 3.7%).     

Host response to malaria during pregnancy: placental monocyte recruitment is associated with elevated beta chemokine expression

Malaria during pregnancy is associated with poor birth outcomes, particularly low birth weight. Recently, monocyte infiltration into the placental intervillous space has been identified as a key risk factor for low birth weight. However, the malaria-induced chemokines involved in recruiting and activating placental monocytes have not been identified. In this study, we determined which chemokines are elevated during placental malaria infection and the association between chemokine expression and placental monocyte infiltration. Placental malaria infection was associated with elevations in mRNA expression of three beta chemokines, macrophage-inflammatory protein 1 (MIP-1) alpha (CCL3), monocyte chemoattractant protein 1 (MCP-1; CCL2), and I-309 (CCL1), and one alpha chemokine, IL-8 (CXCL8); all correlated with monocyte density in the placental intervillous space. Placental plasma concentrations of MIP-1 alpha and IL-8 were increased in women with placental malaria and were associated with placental monocyte infiltration. By immunohistochemistry, we localized placental chemokine production in malaria-infected placentas: some but not all hemozoin-laden maternal macrophages produced MIP-1 beta and MCP-1, and fetal stromal cells produced MCP-1. In sum, local placental production of chemokines is increased in malaria, and may be an important trigger for monocyte accumulation in the placenta.     

Selenium in placenta predicts birth weight in normal but not intrauterine growth restriction pregnancy

Placental selenium, lead and cadmium concentrations were determined in a group of pregnancies with birth weight appropriate for gestational age and in a group of intrauterine growth restriction cases. Following adjustment for a number of confounding variables, selenium was found to be a significant predictor of newborn weight only in the group of pregnancies with birth weights appropriate for gestational age. Placental lead and cadmium levels were not associated with birth weight in either group.     

Atopic dermatitis and birth factors: historical follow up by record linkage.

OBJECTIVE: To study if factors at birth are associated with later development of atopic dermatitis. DESIGN: Historical follow up by record linkage from Danish medical birth register. Children were followed up for 5.5 to 8.5 years. Second historical follow up study comprising questionnaire to mothers of singleborn children 6.5 to 9.5 years after birth. SETTING: Private dermatology clinics and dermatology and paediatric departments in the municipality of Aarhus, Denmark. SUBJECTS: 7862 singletons born in hospital between 1 January 1984 and 31 December 1986 to mothers living in the municipality of Aarhus. Questionnaires sent to 985 mothers. MAIN OUTCOME MEASURES: Gestational age, birth weight, parity, and age of mother at the time of birth. Atopy in children diagnosed by specialists in dermatology and physicians. Family size; diagnosis of atopic dermatitis, allergic rhinitis, and asthma; family predisposition; and mothers'' smoking habits during pregnancy determined from questionnaires. RESULTS: Of 7862 children, 403 were diagnosed as having atopic dermatitis by a specialist; the cumulative incidence at age 7 was 5.6%. High gestational age and low parity were associated with an increased risk of atopic dermatitis. Among 985 children atopic dermatitis had been diagnosed by any physician in 184; the cumulative incidence at age 7 was 18.7%. High birth weight, high gestational age, and family history of atopy were associated with increased risk of atopic dermatitis. CONCLUSION: In both studies the incidence of atopic dermatitis was associated with high gestational age and in one with high birth weight also. The causes for these associations are at present unknown but may indicate that even during gestation factors associated with atopic dermatitis influence maturation.     

Parturition in gilts: duration of farrowing, birth intervals and placenta expulsion in relation to maternal, piglet and placental traits

Large White x Meishan F2 crossbred gilts (n = 57) were observed continuously during farrowing while the placentae of their offspring were labeled in order to examine the duration of farrowing and placenta expulsion in relation to maternal-, piglet- and placental traits and the duration of birth interval in relation to birth weight, birth order and placental traits. Independently from each other, litter size, gestation length and offspring directed aggression significantly (P 0.05) affected duration of farrowing. An increase in litter size was associated with an increase of duration of farrowing and an increase in gestation length was associated with a decrease of duration of farrowing. Aggressive gilts took longer to farrow, compared to non-aggressive ones. After taking into account litter size, gestation length and offspring directed aggression, placental thickness (i.e., placental weight corrected for placental surface area) was significantly (P < 0.05) related to duration of farrowing, i.e., litters with on average thicker placentae took longer to farrow. The latter effect is the result of the fact that individual placental thickness significantly (P < 0.01) affected individual birth interval, independent of birth weight. The piglet has to break its own membranes to be able to start its journey through the uterus towards the birth channel. Apparently, a thicker placenta offers more resistance and thus prolongs the process of birth. Independent of placental thickness, birth interval significantly (P < 0.01) decreased with an increase in birth order (first born to last born). The high variation of birth intervals for the last born piglets, caused a slight increase in average birth interval for the latter piglets. Litters with on average more areolae per placenta took significantly (P < 0.001) less time to be born than litters with on average less areolae per placenta (independent of total number of piglets born and other placental traits), while birth intervals within litters were not affected by this trait. Thus, these results are probably due to a gilt trait rather than a piglet trait. Since the number of areolae represent the number of uterine glands present, the gilt trait might be uterine development. Duration of placenta expulsion significantly (P < 0.01) increased with an increase of duration of farrowing. Furthermore, the first placenta was expelled significantly (P < 0.01) earlier relative to last piglet when duration of farrowing was protracted, while there was no relation of the time interval between first placenta and last piglet and the duration of placenta expulsion. In conclusion, the most important finding of this study is that placental thickness rather than birth weight appears to play an important role in the duration of birth intervals and as a result, of duration of parturition in gilts.     

The expression of Akt and ERK1/2 proteins decreased in dexamethasone-induced intrauterine growth restricted rat placental development

The placenta is a complicated tissue that lies between maternal and fetal compartments. Although the architecture of the human and rodent placentas differ a little in their details, their overall structures and the molecular mechanisms of placental developments are thought to be very similar. In rats, fetal–placental exposure to maternally administered glucocorticoids decreases birth weight and placental weight. The mechanism underlying the placental growth inhibitory effects of glucocorticoids have not been elucidated. Moreover it is still not determined that how Akt and ERK1/2 proteins related proliferation and apoptosis mechanisms are influenced by dexamethasone-induced IUGR (Intrauterine Growth Restriction) placentas. The aim of this study was to investigate the expression levels and spatio-temporal immunolocalizations of Akt, p-Akt, ERK1/2 and p-ERK1/2 proteins in normal and dexamethasone treated placental development in pregnant Wistar rats. Pregnant rats were subcutaneously injected with 100 μg/kg dexamethasone 21-acetate in 0.1 ml 10% ethanol on day 10 and 12 of gestation. Afterwards injection was continued as 200 μg/kg until they were killed on day 12 (injection started on day 10), 14, 16, 18 and 20 (injections started on day 12) of pregnancy. Placental and embryonal tissues were collected for immunohistochemistry and Western blot analysis. We found that maternal dexamethasone treatment led to a decrease in ERK1/2 and Akt activation during rat placental development. The decrease in Akt and ERK1/2 activations may result with cell survival inhibition or apoptosis stimulation. Hence, dexamethasone induced placental and embryonal developmental abnormalities could be associated with reduction of Akt and ERK1/2 activation.