Progesterone administration reduces the behavioural and physiological responses of ewes to abrupt weaning of lambs

Abrupt weaning, a usual management in sheep productive systems, may provoke behavioural and physiological responses indicative of stress in ewes and lambs. Progesterone (P4) has anxiolytic and sedative effects through the union of its metabolites that contain 3α-hydroxyl group to the γ-aminobutyricacid_A receptor. Our first aim was to determine whether P4 administration reduces the behavioural and physiological responses of ewes to abrupt weaning of lambs. A complementary aim was to determine whether P4 treatment affects the milk yield and composition of ewes, and the BW of their lambs. In experiment 1, seven ewes received P4 treatment for 32 days (group E1-P4), and eight ewes remained as an untreated control group (group E1-C). BW of the lambs was recorded during P4 treatment. Lambs were weaned at 59 days (Day 0 = weaning). The main behaviours of the ewes before and after weaning were recorded using 10 min scan sampling. The ewes’ serum total protein, albumin and globulin concentrations were measured before and after weaning of the lambs. In experiment 2, milk yield and composition were determined in two different groups of six ewes treated with P4 (group E2-P4) for 16 days and in five untreated controls (group E2-C). The BW of lambs increased with time (P = 0.001) in both groups and did not differ. The percentage of observations in which the ewes were seen pacing on Day 0 was greater in the E1-C group than in the E1-P4 group (P = 0.0007). Similarly, the percentage of observations in which the ewes were recorded vocalizing on Day 0 was greater in the E1-C group than in the E1-P4 group (P = 0.04). The percentage of observations in which E1-C ewes were recorded lying did not change from Days 0 to 1; however, it increased in E1-P4 ewes. Total serum protein concentration did not change in E1-P4 ewes from Days 0 to 3, although a decrease was seen in E1-C ewes (P = 0.04). Serum globulin concentration was greater in E1-P4 ewes on Day 3 than in E1-C ewes (P = 0.0008). In experiment 2, there were no differences between E2-P4 and E2-C ewes in terms of milk yield, protein, fat and lactose content. Progesterone administration reduced the behavioural and physiological responses of ewes to abrupt weaning of lambs, and this effect was not mediated by changes in milk yield and composition, or by lambs’ BW.     

Psychosocial stress in pregnancy and its relation to low birth weight.

The relation of low birth weight to psychosocial stress in pregnancy was examined using a life events inventory and a state anxiety index. Two hundred and fifty women were randomly selected and interviewed three times during pregnancy and shortly after delivery. Twenty six were excluded. Of the remaining 224 women, nine miscarried, 195 had healthy term babies, and 20 gave birth to babies that were either premature or of low birth weight at term. Low birth weight and prematurity were significantly associated with objective major life events but not state anxiety. The occurrence of objective major life events in the third trimester may be important in precipitating preterm labour. Cigarette smoking was the best predictor and objective major life events the second best predictor of low birth weight. The result was not dependent on social class. These findings suggest that cigarette smoking may be an important mediator of stress on the fetus. Antenatal care should take greater account of stress in pregnancy, and social support systems should be evaluated.     

Thermoregulation of nutrient-restricted hair ewes subjected to heat stress during late pregnancy

In summers with severe hot environmental temperatures, thermoregulation is expected to be critical during the last third of gestation of hair ewes, and this effect can be overstated by suboptimal feeding conditions. Twenty-four multiparous hair sheep ewes with approximately 100 d of pregnancy were randomly assigned to two treatments to evaluate the effects of nutritional restriction (NR) during late gestation on some serum metabolites, physiological variables, and thyroid hormone concentrations under intense heat load (maximum temperature 42–45 °C). Treatments were as follows: (1) control, ewes fed free choice wheat straw plus a concentrate at a rate of 500 g/d, and (2) nutritionally-restricted (NR) ewes, which were offered wheat straw only ad libitum. Body weight of NR ewes dropped 5.1 kg (P<0.05), while control ewes gained 4.7 kg during the study period. Rectal temperature was not affected (P>0.05) by feeding regime either in the morning or afternoon hours. Respiration rate was greater (P<0.05) in control ewes (20 and 40 breaths/min higher in the day and night, respectively) on d 130 and 145 of pregnancy compared to NR ewes. Skin temperatures during the morning and afternoon were affected (P<0.05) by feeding regime at d 130 and 145 of pregnancy. In the morning, NR ewes presented greater (P<0.05) head and rump temperature at day 145 of gestation, and lower (P<0.05) udder temperatures at d 130 and 145 than control ewes. In the afternoon, skin temperatures of NR ewes were higher (P<0.05) in head and right flank on d 130 and 145 of pregnancy, and in udder at day 145 compared to control ewes. Serum glucose was higher (P<0.05) in NR ewes than control animals at day 145 of pregnancy. Serum cholesterol, triglyceride and thyroid hormones were not affected by nutritional restriction. Overall, it was found that nutritionally restricted ewes were less affected by intense heat loads than well-fed ewes, apparently due to the lower metabolic heat produced by this underfed animals. Also, it was apparent that the lower respiration rate of NR ewes was compensated by a greater body surface temperature.     

Maternal serum progesterone concentration during pregnancy and lamb birth weight at parturition in Javanese Thin-Tail ewes with different litter sizes

Pregnant ewes, (N=38), with similar body weight and age (19, 13 and 6 carrying 1, 2 and 3 fetuses, respectively) were used to study the relationship between maternal serum progesterone concentration during pregnancy and lamb birth weight at parturition. Average maternal serum progesterone concentration in the ewes carrying 1, 2, and 3 fetuses was: 5.3±0.3, 6.2±0.7 and 6.6±0.5 ng/ml, during weeks 0 to 7 of gestation; 16.9±1.4, 25.3±1.5, and 26.8±2.5 ng/ml, during weeks 8 to 20; and 13.2±1.0, 18.7±1.0, and 19.8±1.7 ng/ml, during the entire gestation period respectively. Total lamb birth weight in ewes carrying 1, 2, and 3 fetuses was 1.9±0.1, 3.2±0.2, and 4.2±0.4 kg, respectively. In the respective litter sizes, ewes with higher mean serum progesterone concentration during the whole pregnancy gave birth to lambs with higher birth weight (r²=0.76, 0.42 and 0.46, for ewes carrying 1, 2 and 3 fetuses, respectively). The results of the study indicated that prenatal growth could probably be improved by increasing endogenous secretion of maternal progesterone during pregnancy.     

Urogenital schistosomiasis during pregnancy is associated with low birth weight delivery: analysis of a prospective cohort of pregnant women and their offspring in Gabon

An estimated 40 million women of childbearing age suffer from schistosomiasis. Animal models indicate a deleterious effect of maternal schistosomiasis on pregnancy outcomes. To date there is a lack of epidemiological evidence evaluating schistosomiasis-related morbidity in pregnancy. This study was designed to describe the impact of urogenital schistosomiasis on pregnancy outcomes in a highly endemic region of central Africa. Pregnant women attending antenatal clinics in Fougamou and Lambaréné, Gabon, were consecutively screened for the presence of Schistosoma haematobium eggs in diurnal urine samples. Maternal and newborn characteristics assessed at delivery were compared between infected and uninfected mothers. The impact of maternal schistosomiasis on low birth weight and preterm delivery was assessed using logistic regression analysis. Urogenital schistosomiasis was diagnosed in 103 (9%) of 1115 pregnant women. Maternal age was inversely associated with the prevalence of urogenital schistosomiasis, with a higher burden amongst nulliparous women. Low birth weight was more common amongst infants of S. haematobium-infected mothers. This association was unaffected by controlling for demographic characteristics, gestational age and Plasmodium infection status (adjusted Odds Ratio 1.93; 95% confidence interval: 1.08–3.42). Other risk factors associated with low birth weight delivery were underweight mothers (adjusted Odds Ratio 2.34; 95% confidence interval: 1.12–4.92), peripheral or placental Plasmodium falciparum infection (adjusted Odds Ratio 2.04; 95% confidence interval: 1.18–3.53) and preterm birth (adjusted Odds Ratio 3.12; 95% confidence interval: 1.97–4.96). Preterm delivery was not associated with S. haematobium infection (adjusted Odds Ratio 1.07 95% confidence interval: 0.57–1.98). In conclusion, this study indicates that pregnant women with urogenital schistosomiasis are at an increased risk for low birth weight deliveries. Further studies evaluating targeted treatment and prevention programmes for urogenital schistosomiasis in pregnant women and their impact on delivery outcomes are warranted.     

Mothers' birth weight and survival of their offspring: population based study.

OBJECTIVE: To test the hypothesis that a baby''s survival is related to the mother''s birth weight. DESIGN: Population based dataset for two generations. SETTING: Population registry in Norway. SUBJECTS: All birth records for women born in Norway since 1967 were linked to births during 1981-94, thereby forming 105104 mother-offspring units. MAIN OUTCOME MEASURES: Perinatal mortality specific for weight for offspring in groups of maternal birth weight (with 500 g categories in both). RESULTS: A mother''s birth weight was strongly associated with the weight of her baby. Maternal birth weight was associated with perinatal survival of her baby only for mothers with birth weights under 2000 g. These mothers were more likely to lose a baby in the perinatal period (odds ratio 2.3, 95% confidence interval 1.4 to 3.7). Among mothers with a birth weight over 2000 g there was no overall association between mother''s weight and infant survival. There was, however, a strong interaction between mother''s birth weight, infant birth weight, and infant survival. Mortality among small babies was much higher for those whose mothers had been large at birth. For example, babies weighing 2500-2999 g had a threefold higher mortality if their mother''s birth weight had been high (> or = 4000 g) than if the mother had been small (2500-2999 g). CONCLUSION: Mothers who weighed less than 2000 g at birth have a higher risk of losing their own babies. For mothers who weighed > or = 2000 g their birth weight provides a benchmark for judging the growth of their offspring. Babies who are small relative to their mother''s birth weight are at increased risk of mortality.     

Effects of ectoparasite infestation during pregnancy on physiological stress and reproductive output in a rodent-flea system

Biotic and abiotic stressors impose various fitness costs on individuals across a variety of taxa. In vertebrates, these stressors typically trigger complex neuroendocrine responses that stimulate glucocorticoid (GC) secretion from the adrenal cortex. Short-term elevation of GCs can be adaptive as it shifts energy toward physiological processes that cope with acute stressors; however, chronic increases in GC levels could have detrimental effects on fitness. Parasitism can be considered an important biotic stressor in nature and a possible cause of reproductive failure that could substantially affect an individual’s fitness. Thus, we aimed to test the effects of parasitism and maternal stress, as measured by GCs, during pregnancy and the relationship between these variables and measures of reproductive output using a rodent-flea system. Female Egyptian spiny mice (Acomys cahirinus) were randomly assigned to flea (Parapulex chephrenis) infested or uninfested treatments before and during pregnancy. The offspring of these females were flea-free. Feces were collected at five time points during the experiment to determine maternal fecal glucocorticoid metabolite (FGCM) concentrations. Overall, infested females had lower FGCM levels during gestation but higher FGCM levels post-parturition and larger mass changes than uninfested females. Additionally, models related to pup quality and quantity often included some measure of maternal investment or body condition moderating relationships between infestation and stress. This suggests that flea parasitism or high GC levels alone might not significantly impact host reproduction but rather females can experience different effects depending on their level of investment, which could be limited by body condition and/or the number of pups present in a litter.     

Effects of the presence of rams during pregnancy on lambing performance in ewes

Ewes of the Préalpes-du-Sud breed (n=112) were mated with fertile rams and were used to investigate the effect of the presence of vasectomized rams during pregnancy on reproductive outcomes. Ewes in the control group (n=56) were isolated from rams during the whole period of pregnancy, whereas those in the experimental group (n=56) were kept with vasectomized rams from day 10 post-mating until lambing. At day 10 post-mating, a series of blood samples was collected every 15 min for 8 h from five control ewes and five experimental ewes to determine their patterns of LH secretion. The introduction of the ram was associated with a rapid increase of pulsatile LH release. The lag between the introduction of the ram and the onset of the first episodic LH release was less than 15 min. The mean(±sem) number of LH pulses/4 h after the introduction of the ram (2.8±0.4) was significantly higher (P<0.01) than that observed/4 h before the introduction of the ram (1.4±0.2). Although more ewes were pregnant in the control group (87.5%) than in the ram-exposed group (82.1%), the difference was not significant. The presence of rams did not affect gestation length (145.8 days), overall lamb mortality (3.5%) or birth weights of single (3.96 kg), twin (3.24 kg) or triplet (2.59 kg) lambs. The proportion of ewes with multiple births in the control group (69.4%) was significantly greater (P<0.05) than that in the ram-exposed ewes (47.8%). The ewes in the control group had significantly more (P<0.01) twin lambs born alive (72.3%) than the ewes in the ram-exposed group (50.0%). In conclusion, the presence of vasectomized rams during early pregnancy affected the incidence of multiple births but did not affect pregnancy rate or gestation length. The altered fertility of ewes exposed to vasectomized rams may reflect changes in embryonic loss during early pregnancy.     

Low pasture allowance until late gestation in ewes: behavioural and physiological changes in ewes and lambs from lambing to weaning

Low pasture allowance during gestation affects ewes’ BW at parturition, the bond with their lamb, lamb development, and thus also may affect their responses to weaning. The objectives were to determine if native pasture allowance from before conception until late pregnancy affects ewe–lamb behaviours at lambing, ewes’ milk yield, lambs’ BW, and the behavioural and physiological changes of ewes and lambs at weaning. From 23 days before conception until 122 days of pregnancy, 24 ewes grazed on two different native pasture allowances: high (10 to 12 kg of dry matter (DM)/100 kg of BW per day; HPA treatment; n=12) or low (5 to 8 kg of DM/100 kg of BW per day; LPA treatment; n=12). Thereafter, all ewes grazed on Festuca arundinacea and received rice bran and crude glycerine. Ewes’ body condition score (BCS) and BW were recorded during pregnancy and postpartum periods. Milk yield was determined on days 32, 41 and 54 after lambing. Lambs’ BW was recorded from birth until 72 days after lambing. Latency from parturition until the ewe licked her lamb, maternal behaviour score (a test that evaluates maternal attachment to the lamb) and latency for lamb to stand up and suckle were determined. The behaviour of the lambs and ewes was recorded before and after weaning (at 65 days). The ewes’ serum total protein, albumin and globulin concentrations were measured before and after weaning. The HPA ewes presented greater BW (P<0.005) and BCS (P<0.005) than the LPA ewes during pregnancy and postpartum (P<0.04), and had a greater milk yield than the LPA ewes (P<0.03). Treatments did not influence any behaviour at lambing, lambs’ BW, neither the ewes’ behavioural and physiological changes at weaning. HPA lambs paced and vocalized more than LPA lambs (P<0.0001). The variation of albumin concentration before and after weaning was greater in the HPA lambs than in the LPA lambs (P<0.0001). In conclusion, although ewes’ BW, BCS and milk production were affected by pasture allowance until late pregnancy, this did not affect the behaviours that lead to the establishment of the mother–young bond, nor the ewes’ behavioural responses at weaning. Lambs reared by ewes that grazed on low pasture allowance during pregnancy presented fewer behavioural changes and a lower decrease of albumin concentration after weaning. Lambs’ BW was not affected by the feeding received by their mothers.     

Effects of quercetin on predator stress-related hematological and behavioural alterations in pregnant rats and their offspring

This study aims at investigating the effect of a psychogenic stress during gestation on the behaviour and haematological indices in dams as well as on the neonatal haematological status and periadolescent behaviour in their offspring. Moreover, the ability of quercetin, a natural flavonoid, to prevent the stress-induced changes was estimated. Pregnant Wistar rats were pretreated with quercetin before the exposure to a predator stress on gestational day 19. Post-stress maternal anxiety-like behaviour was assessed with a concomitant haematological analysis. In the offspring, haematological analysis and behavioural testing were performed during the postnatal stage. Our results revealed that predator stress causes an anxiety-like behaviour in dams along with a decrease in erythrocytes, a microcytosis, and a thrombocytosis. Prenatally stressed neonates manifested microcytosis and thrombocytosis with a significant polycythemia. Signs of motor hyperactivity, anxiety-like behaviour, and memory dysfunction were detected at periadolescence. Quercetin pretreatment alleviated the stress-induced behavioural and haematological impairments in dams but failed to attenuate the haematological changes in neonates. A sex-dependent effect of quercetin on behaviour was found at periadolescence. Our findings suggest that, besides a beneficial effect on haematological and behavioural anomalies in traumatized dams, quercetin may lastingly modulate the behaviour of their progeny.     

Consumption of a high-salt diet by ewes during pregnancy alters nephrogenesis in 5-month-old offspring

Maternal nutrition during pregnancy can affect kidney development in the foetus, which may lead to adverse consequences in the mature kidney. It was expected that high-salt intake by pregnant ewes would lead to a reduction in foetal glomerular number but that the ovine kidney would adapt to maintain homoeostasis, in part by increasing the size of each glomerulus. Merino ewes that were fed either a control (1.5% NaCl) or high-salt (10.5% NaCl) diet during pregnancy, as well as their 5-month-old offspring, were subjected to a dietary salt challenge, and glomerular number and size and sodium excretion were measured. The high-salt offspring had 20% fewer glomeruli compared with the control offspring (P < 0.001), but they also had larger glomerular radii compared with the control offspring (P < 0.001). Consequently, the cross-sectional area of glomeruli was 18% larger in the high-salt offspring than in the control offspring (P < 0.05). There was no difference in the daily urinary sodium excretion between the two offspring groups (P > 0.05), although the high-salt offspring produced urine with a higher concentration of sodium. Our results demonstrated that maternal high-salt intake during pregnancy affected foetal nephrogenesis, altering glomerular number at birth. However, the ability to concentrate and excrete salt was not compromised, which indicates that the kidney was able to adapt to the reduction in the number of glomeruli.     

Effects of progesterone on the responses of Merino ewes to the introduction of rams during anoestrus

The effects of progesterone on the responses of Merino ewes to the introduction of rams during anoestrus were investigated in two experiments. In the first experiment, the introduction of rams induced an increase in the levels of LH in entire ewes. The mean levels increased from 0.68 +/- 0.04 ng/ml (mean +/- s.e.m.) to 4.49 +/- 1.32 ng/ml within 20 min in ewes not treated with progesterone (n = 10). In ewes bearing progesterone implants that provided a peripheral concentration of about 1.5 ng progesterone per millilitre plasma, the LH response to the introduction of rams was not prevented, but was reduced in size so that the concentration was 1.38 +/- 0.15 ng/ml after 20 min (n = 5). Progesterone treatment begun either 2 days before or 6 h after the introduction of rams and maintained for 4 days prevented ovulation. In the second experiment ovariectomized ewes were used to investigate further the mechanism by which the ram evoked increases in tonic LH secretion. In ovariectomized ewes treated with oestradiol implants, the introduction of rams increased the frequency of the LH pulses and the basal level of LH. In the absence of oestradiol there was no significant change in pulse frequency but a small increase in basal levels. Progesterone again did not prevent but reduced the responses in ewes treated with oestradiol. It is suggested that following the withdrawal of progesterone treatment, the secretion of LH pulses in response to the ram effect would be dampened. This effect could be a component of the reported long delay between the introduction of rams and the preovulatory surge of LH in ewes treated with progesterone. Continued progesterone treatment prevented ovulation, probably by blocking positive feedback by oestradiol.     

Effects of stress on reproduction in ewes

Stressors, such as poor body condition, adverse temperatures or even common management procedures (e.g., transport or shearing) suppress normal oestrus behaviour and reduce ewe fertility. All these events are co-ordinated by endocrine interactions, which are disrupted in stressful situations. This disruption is usually temporary in adult ewes, so that, when prevailing conditions improve, normal fertility would resume. Imposition of an experimental stressor (shearing, transport, isolation from other sheep, injection of endotoxin or insulin or cortisol infusion) suppresses GnRH/LH pulse frequency and amplitude. Part of the cause is at the pituitary, but effects on GnRH/LH pulse frequency and the GnRH/LH surge are mediated via the hypothalamus. It is not yet clear whether delays in the surge are caused by interruption of the oestradiol signal-reading phase, the signal transmission phase or GnRH surge release. Stressors also delay the onset of behaviour, sometimes distancing this from the onset of the pre-ovulatory LH surge. This could have deleterious consequences for fertility.     

Housing conditions differentially affect physiological and behavioural stress responses of zebrafish, as well as the response to anxiolytics

Zebrafish are a widely utilised animal model in developmental genetics, and owing to recent advances in our understanding of zebrafish behaviour, their utility as a comparative model in behavioural neuroscience is beginning to be realised. One widely reported behavioural measure is the novel tank-diving assay, which has been often cited as a test of anxiety and stress reactivity. Despite its wide utilisation, and various validations against anxiolytic drugs, reporting of pre-test housing has been sparse in the literature. As zebrafish are a shoaling species, we predicted that housing environment would affect their stress reactivity and, as such, their response in the tank-diving procedure. In our first experiment, we tested various aspects of housing (large groups, large groups with no contact, paired, visual contact only, olfactory contact only) and found that the tank diving response was mediated by visual contact with conspecifics. We also tested the basal cortisol levels of group and individually housed fish, and found that individually housed individuals have lower basal cortisol levels. In our second experiment we found ethanol appeared to have an anxiolytic effect with individually housed fish but not those that were group housed. In our final experiment, we examined the effects of changing the fishes' water prior to tank diving as an additional acclimation procedure. We found that this had no effect on individually housed fish, but appeared to affect the typical tank diving responses of the group housed individuals. In conclusion, we demonstrate that housing represents an important factor in obtaining reliable data from this methodology, and should be considered by researchers interested in comparative models of anxiety in zebrafish in order to refine their approach and to increase the power in their experiments.     

Stunning fish with CO2 or electricity: contradictory results on behavioural and physiological stress responses

Studies that address fish welfare before slaughter have concluded that many of the traditional systems used to stun fish including CO₂ narcosis are unacceptable as they cause avoidable stress before death. One system recommended as a better alternative is electrical stunning, however, the welfare aspects of this method are not yet fully understood. To assess welfare in aquaculture both behavioural and physiological measurements have been used, but few studies have examined the relationship between these variables. In an on-site study aversive behaviours and several physiological stress indicators, including plasma levels of cortisol and ions as well as blood physiological variables, were compared in Arctic char (Salvelinus alpinus) stunned with CO₂ or electricity. Exposure to water saturated with CO₂ triggered aversive struggling and escape responses for several minutes before immobilization, whereas in fish exposed to an electric current immobilization was close to instant. On average, it took 5 min for the fish to recover from electrical stunning, whereas fish stunned with CO₂ did not recover. Despite this, the electrically stunned fish had more than double the plasma levels of cortisol compared with fish stunned with CO₂. This result is surprising considering that the behavioural reactions were much more pronounced following CO₂ exposure. These contradictory results are discussed with regard to animal welfare and stress physiological responses. The present results emphasise the importance of using an integrative and interdisciplinary approach and to include both behavioural and physiological stress indicators in order to make accurate welfare assessments of fish in aquaculture.     

Maternal exposure to exogenous sex hormones in relation to birth weight of offspring

Birth weight was analyzed among singleton live births (N = 665) in Upstate New York in 1974 to women who used oral contraceptives (OC) in comparison to live births to women who used no contraceptives (N = 716), within 11 months prior to last menstrual period (LMP). In addition, birth weight was examined among live births to women who received hormone support therapy (N = 97) and hormone pregnancy tests (N = 75) during pregnancy. There was no evidence for a reduction in mean birth weight, or an increase in frequency of lower weights, among births to OC users, including those who stopped using OC within 2 months of LMP. Generally similar findings held within three maternal age groups (less than 25, 25-29, and 30-39 years). There was no evidence for a reduction in birth weight among offspring of women who received hormone pregnancy tests. Mean birth weight was relatively low among male and female births to women who received hormone therapy for "threatened abortion," but this may reflect the selection of women for such treatment rather than an effect of exogenous hormones on fetal growth.     

Effects of grandmothers' smoking in pregnancy on birth weight: intergenerational cohort study

Objective To investigate the influences on birth weight of maternal smoking during pregnancy across generations.Design Intergenerational cohort study.Participants Members of the 1958 birth cohort and their offspring and mothers.Setting England, Scotland, and Wales.Main outcome measure Birth weight.Results Information on grandmothers'' smoking during pregnancy was available for 9028 singleton offspring of 4302 female cohort members. Assuming heritable transmission through the intergenerational association, grandmothers'' smoking was predicted to result in a 34 g reduction (95% confidence interval -41 g to -28 g) in the birth weight of grandchildren. Random effects models showed a negative association between grandmothers'' smoking and birth weight of grandchildren (β regression coefficient -24 g, -50 g to 3 g), but this effect was eliminated after adjustment for maternal smoking (0 g, -26 g to 26 g).No association was evident among the offspring of non-smoking mothers (n = 6105; 14 g, -17 g to 46 g), and after adjustment for maternal birth weight, adult height and body mass index, grandmothers'' smoking was positively associated with the birth weight of grandchildren (45 g, 10 g to 80 g).Conclusion Deficits in mothers'' birth weight attributable to their mother smoking was not evident in the grandchildren.