Parental pre-pregnancy BMI is a dominant early-life risk factor influencing BMI of offspring in adulthood

Objective

We examined parental and early‐life variables in order to identify risk factors for adulthood overweight and obesity in offspring. We report here on the longitudinal prevalence of overweight and obesity in Australian children born between 1989 and 1991 and followed from birth to age 22.

Methods

Data were analysed on 1355 participants from the Western Australian Pregnancy Cohort (Raine) Study, with anthropometry collected during pregnancy, at birth, one year and at three yearly intervals thereafter. Multivariate analyses and cross‐sectional logistic regression quantified the timing and contribution of early‐life risk factors for overweight and obesity in young‐adulthood.

Results

At five years of age 12.6% of children were overweight and 5.2% were obese. By early adulthood, the prevalence of obesity had increased to 12.8%, whilst overweight remained relatively stable at 14.2% (range from early childhood to adulthood 11–16%). Parental pre‐pregnancy body mass index (BMI) was the strongest determinant of adult offspring BMI. Although rapid first year weight gain was associated with increased offspring BMI, the impact of first year weight‐gain diminished over childhood, whilst the impact of parental BMI increased over time.

Conclusions

Parental pre‐pregnancy BMI and rapid early‐life weight gain predispose offspring to obesity in adulthood.

The clinical use of corticosteroids in pregnancy

BACKGROUND

The use of antenatal steroid therapy is common in pregnancy. In early pregnancy, steroids may be used in women for the treatment of recurrent miscarriage or fetal abnormalities such as congenital adrenal hyperplasia. In mid-late pregnancy, the antenatal administration of corticosteroids to expectant mothers in anticipation of preterm birth is one of the most important advances in perinatal medicine; antenatal corticosteroids are now standard care for pregnancies at risk of premature delivery in high- and middle-income countries. The widespread uptake of this therapy is due to a compelling body of evidence demonstrating improved neonatal outcomes following antenatal corticosteroid exposure, stemming most notably from corticosteroid-driven maturation of fetal pulmonary function. As we approach the 50th anniversary of landmark work in this area by Liggins and Howie, it is apparent that much remains to be understood with regards to how we might best apply antenatal corticosteroid therapy to improve pregnancy outcomes at both early and mid to late gestation.

METHODS

Drawing on advances in laboratory science, pre-clinical and clinical studies, we performed a narrative review of the scientific literature to provide a timely update on the benefits, risks and uncertainties regarding antenatal corticosteroid use in pregnancy. Three, well-established therapeutic uses of antenatal steroids, namely recurrent miscarriage, congenital adrenal hyperplasia and preterm birth, were selected to frame the review.

RESULTS

Even the most well-established antenatal steroid therapies lack the comprehensive pharmacokinetic and dose-response data necessary to optimize dosing regimens. New insights into complex, tissue-specific corticosteroid signalling by genomic-dependent and independent mechanisms have not been used to inform corticosteroid treatment strategies. There is growing evidence that some fetal corticosteroid treatments are either ineffective, or may result in adverse outcomes, in addition to lasting epigenetic changes in a variety of homeostatic mechanisms. Nowhere is the need to better understand the intricacies of corticosteroid therapy better conveyed than in the findings of Althabe and colleagues who recently reported an increase in overall neonatal mortality and maternal morbidity in association with antenatal corticosteroid administration in low-resource settings.

CONCLUSIONS

New research to clarify the benefits and potential risks of antenatal corticosteroid therapy is urgently needed, especially with regard to corticosteroid use in low-resource environments. We conclude that there is both significant scope and an urgent need for further research-informed refinement to the use of antenatal corticosteroids in pregnancy.

Effects of maternal dexamethasone treatment early in pregnancy on glucocorticoid receptors in the ovine placenta

The effects of endogenous cortisol on binucleate cells (BNCs), which promote fetal growth, may be mediated by glucocorticoid receptors (GRs), and exposure to dexamethasone (DEX) in early pregnancy stages of placental development might modify this response. In this article, we have investigated the expression of GR as a determinant of these responses. Pregnant ewes carrying singleton fetuses (n = 119) were randomized to control (2 mL saline/ewe) or DEX-treated groups (intramuscular injections of 0.14 mg/kg ewe weight per 12 hours) at 40 to 41 days of gestation (dG). Placental tissue was collected at 50, 100, 125, and 140 dG. Total glucocorticoid receptor protein (GRt) was increased significantly by DEX at 50 and 125 dG in females only, but decreased in males at 125 dG as compared to controls. Glucocorticoid receptor α (GRα) protein was not changed after DEX treatment. Three BNC phenotypes were detected regarding GRα expression (++, +-, --), DEX increased the proportion of (++) and decreased (--) BNC at 140 dG. Effects were sex- and cell type dependent, modifying the responsiveness of the placenta to endogenous cortisol. We speculate that 3 maturational stages of BNCs exist and that the overall activity of BNCs is determined by the distribution of these 3 cell types, which may become altered through early pregnancy exposure to elevated glucocorticoids.

Multiple prenatal ultrasound scans and ocular development: 20-year follow-up of a randomized controlled trial

OBJECTIVES

Through comprehensive ophthalmic examination of adult offspring we sought to determine the impact of multiple prenatal ultrasound scans on ocular development.

METHODS

2743 pregnant women recruited to the Western Australian Pregnancy (Raine) Cohort study during 1989-1991 were randomized to receive at King Edward Memorial Hospital, Western Australia either multiple prenatal ultrasound scans and Doppler flow studies (intensive group) or a single ultrasound scan at 18 weeks' gestation. Neonatal birth weight of the offspring and other physical measurements were collected prospectively. At age 20 years, participants underwent a comprehensive ophthalmic examination including measurement of ocular biometry and visual acuity.

RESULTS

Complete data were available for 1134 adult offspring participants. The mothers of 563 of these had been randomized to receive multiple prenatal ultrasound scans. The mean age of participants at follow-up was 20.0 years. There was no statistically significant difference between the two groups with regard to ocular biometric or visual outcomes, except for slightly higher intraocular pressure identified in individuals exposed to multiple ultrasound scans (P = 0.034). Although infants in the intensive-ultrasound arm were more likely to have birth weights in the lower quartiles, this was not reflected in adult eye development. Axial length, lens thickness, corneal curvature and thickness and optic cup to disc ratio (a risk factor for glaucomatous optic neuropathy) were not significantly influenced by the more frequent ultrasound protocol.

CONCLUSIONS

Prior to this study, there was a paucity of safety data for ultrasound with regard to eye development. We found that frequent in-utero exposure to ultrasound, including B-mode imaging and the use of spectral Doppler mode from 18 weeks' gestation, had no significant impact on visual outcomes or ocular biometry.

Frequent nocturnal awakening in early life is associated with nonatopic asthma in children

Sleep deprivation has become a common phenomenon of the Western world and is associated with a variety of medical problems in children. This retrospective longitudinal analysis of a community-based birth cohort was undertaken to determine whether frequent nocturnal awakening during early life was associated with the development of childhood asthma. 2,398 children born to mothers recruited from the antenatal clinics of a single hospital in Perth, Australia during 1989-1991 were followed up at years 1, 2, 3, 6, 8, 10 and 14. Parent-completed questionnaires were analysed. The odds ratio for asthma at age 6 and 14 yrs in children with frequent nocturnal awakening during the first 3 yrs after birth was determined from multiple logistic regression. Following adjustment for asthma risk factors, co-sleeping and family stress, persistent nocturnal awakening was associated with nonatopic asthma at age 6 and 14 yrs (at age 14 yrs: OR 2.18, 95% CI 1.15-4.13) but not with atopic asthma. We found an increased risk of nonatopic asthma in children following frequent nocturnal awakening during the first 3 yrs of life. These hypothesis-generating data suggest the need for further systematic study of the effects of disordered sleep in early life on the development of asthma.

The relationship between maternal and umbilical cord androgen levels and polycystic ovary syndrome in adolescence: a prospective cohort study

CONTEXT

The prenatal antecedents of polycystic ovary syndrome (PCOS) are not known, but prenatal androgen exposure is thought to contribute. This has not previously been investigated in large prospective studies of normal human pregnancy.

OBJECTIVE

The aim of the study was to establish the prospective relationship between early life androgen exposure and PCOS in adolescence.

DESIGN AND SETTING

A prospective cohort study was conducted in the general community.

PATIENTS OR OTHER PARTICIPANTS

A total of 2900 pregnant women were recruited at 18 wk gestation. Prenatal androgen exposure was measured from maternal blood samples (at 18 and 34-36 wk) and umbilical cord blood. Timed (d 2-5 menstrual cycle) blood samples were collected, clinical hyperandrogenism was assessed, and transabdominal ultrasound examination of ovarian morphology was performed in 244 unselected girls from the Raine cohort aged 14-17 yr.

MAIN OUTCOME MEASURE(S)

We examined the relationship between early life androgen exposure and PCOS in adolescence.

RESULTS

We did not observe a statistically significant relationship between early life androgen exposure and PCOS in adolescence.

CONCLUSIONS

This is the first prospective study to evaluate the relationship between prenatal androgen exposure and PCOS in adolescence in normal pregnancy. Our findings do not support the hypothesis that maternal androgens, within the normal range for pregnancy, directly program PCOS in the offspring.

Effectiveness and safety of a structured swimming program in previously sedentary women during pregnancy

OBJECTIVE

To determine whether undertaking a swimming program in sedentary women during pregnancy would improve maternal fitness without adverse fetal consequences.

METHODS

Prospective observational investigation of healthy sedentary pregnant women participating in a monitored swimming program.

RESULTS

Twenty-three women attended swimming sessions from 16 to 28 weeks of gestation resulting in increasing distances swum and improved aerobic fitness as measured by physical work capacity (PWC170) (p = 0.003). Resting maternal heart rate decreased (p = 0.041) and resting systolic (p = 0.092) and diastolic (p = 0.971) blood pressures remained unchanged over gestation. The mean fetal heart rates decreased with advancing gestational age (p = 0.001), consistent with normal physiology. Non-stress tests and umbilical artery systolic/diastolic ratios were similar before and after swimming sessions, providing evidence that fetal well-being was unchanged.

CONCLUSIONS

A structured swimming program in sedentary pregnant women increases maternal fitness without any alteration in maternal and fetal well-being.

The prediction of pregnancy outcome by haemoglobin measurement before 20 weeks` gestation

Maternal haemoglobin levels were measured before 21 weeks' gestation in a prospective study of 1276 singleton pregnancies. Reference ranges were constructed and then applied to a further cohort of 1227 singleton pregnancies to determine the ability of haemoglobin level before 21 weeks' gestation to predict pregnancy outcome. Haemoglobin level decreased significantly with advancing gestational age from 6 to 21 weeks (P < 0.05). Low haemoglobin level was associated with a decreased risk of pregnancy-induced hypertension (adjusted odds ratio 0.51, 95% CI 0.35-0.74). High haemoglobin level was positively correlated with subsequent pregnancy-induced hypertension (P = 0.002) with values > 95th percentile for gestational age having positive and negative predictive values of 33% and 94% respectively. Haemoglobin values (either high or low) were not predictive of proteinuric pre-eclampsia, preterm prelabour rupture of the membranes, preterm birth, low birth weight or the need for neonatal resuscitation of admission to the special care baby unit. The finding of a high maternal haemoglobin before 21 weeks' gestation is not sufficiently predictive of pregnancyinduced hypertension to be of clinical use, but the ability of a low level to predict favourable outcome may be of use in a scoring system designed to identify women suitable for midwifery-based care.

Second trimester placental location as a predictor of an adverse pregnancy outcome

OBJECTIVE

To determine if the second trimester placental location is associated with perinatal outcomes.

MATERIALS AND METHODS

Observational study of placental location and the subsequent risk of an adverse pregnancy outcome. Placental location was divided into three categories, low, high lateral and high fundal.

RESULTS

There were 3336 pregnancies analyzed in this study. Low implantation sites had a greater risk of preterm labor (odds ratio (OR) 1.70, 95% confidence interval (CI) 1.38 to 2.90, P<0.001), preterm delivery (OR 1.86, 95% CI 1.36 to 2.54, P<0.001), fewer fetuses with macrosomia (OR 0.56, 95% CI 0.38 to 0.83, P=0.010) and reduced risk of postpartum hemorrhage (OR 0.56, 95% CI 0.46 to 0.95, P=0.026). High lateral implantations had a greater risk of low 1-min (OR 1.80, 95% CI 1.11 to 2.93, P=0.017) and 5-min (OR 3.49, 95% CI 1.46 to 8.36, P=0.005) Apgar scores.

CONCLUSIONS

Low placental implantation was associated with an increased risk of preterm labor, preterm delivery and a reduced risk of postpartum hemorrhage, and of a macrosomic fetus. High lateral implantation was associated with low Apgar scores.

Pre-pregnancy body mass index and pregnancy outcomes

OBJECTIVE

To determine the effect of maternal pre-pregnancy BMI on pregnancy outcomes.

METHODS

Pregnancy cohort recruited pregnancies between 16 and 18 weeks. BMI evaluated underweight, BMI<18.5, normal, BMI 18.5-25, overweight BMI 25-30, and obese BMI>30 women.

RESULTS

Pre-pregnancy BMI classified 331 women as underweight (11.7%), 1982 normal (69.9%), 326 overweight (11.5%), and 188 as obese (6.6%). Obese women were more likely to develop gestational diabetes (p<0.001), hypertension (p<0.001), preeclampsia (p<0.001), need labor induction (p<0.001), cesarean delivery for fetal distress (p<0.001), postpartum hemorrhage (p=0.003), need neonatal resuscitation (p=0.001) and deliver hypoglycemic infants (p=0.007). Being underweight is correlated with fetal growth restriction (p=0.001).

CONCLUSION

Pre-pregnancy obesity is a risk factor for gestational diabetes, preeclampsia, labor induction, cesarean for fetal distress, postpartum hemorrhage and neonatal hypoglycemic and need for resuscitation. Being underweight is risk factor for fetal growth restriction.

Perinatal and childhood origins of cardiovascular disease

BACKGROUND

Features of the metabolic syndrome comprise a major risk for cardiovascular disease and will increase in prevalence with rising childhood obesity. We sought to identify early life influences on development of obesity, hypertension and dyslipidemia in children.

METHODS AND RESULTS

Cluster analysis was used on a subset of a longitudinal Australian birth cohort who had blood samples at age 8 (n=406). A quarter of these 8-year-olds fell into a cluster with higher body mass index, blood pressure (BP), more adverse lipid profile and a trend to higher serum glucose resembling adult metabolic syndrome. There was a U-shaped relationship between percentage of expected birth weight (PEBW) and likelihood of being in the high-risk cluster. The high-risk cluster had elevated BP and weight as early as 1 and 3 years old. Increased likelihood of the high-risk cluster group occurred with greatest weight gain from 1 to 8 years old (odds ratio (OR)=1.4, 95% confidence interval (CI)=1.3-1.5/kg) and if mothers smoked during pregnancy (OR=1.82, CI=1.05-3.2). Risk was lower if children were breast fed for >/=4 months (OR=0.6, 95% CI=0.37-0.97). Newborns in the upper two quintiles for PEBW born to mothers who smoked throughout pregnancy were at greatest risk (OR=14.0, 95% CI=3.8-51.1) compared to the nadir PEBW quintile of non-smokers.

CONCLUSION

A U-shaped relationship between birth weight and several components of the metabolic syndrome was confirmed in a contemporary, well-nourished Western population of full-term newborns, but post-natal weight gain was the dominant factor associated with the high-risk cluster. There was a prominence of higher as well as lowest birth weights in those at risk. Future health programs should focus on both pre- and post-natal factors (reducing excess childhood weight gain and smoking during pregnancy), and possibly the greatest benefits may arise from targeting the heaviest, as well as lightest newborns, especially with a history of maternal smoking during pregnancy.

Synthetic glucocorticoids: antenatal administration and long-term implications

A clear relationship between intrauterine development and later life predisposition to long-term disease is well established. Weight at birth provides a surrogate measure for fetal development and low birth weight predicts changes in most endocrine axes in adulthood. The exposure of the fetus to elevated levels of either endogenous or synthetic glucocorticoids, pre and periconceptional nutritional status and immediate postnatal development including catch-up growth all contribute substantially to the development of adult onset disease. Fetal exposure to high levels of glucocorticoids has direct clinical relevance. Synthetic glucocorticoids (betamethasone/ dexamethasone) are administered to women at risk of preterm delivery to advance fetal maturation and reduce neonatal morbidity and mortality. However, in human pregnancy, evidence suggests that fetal exposure to synthetic glucocorticoids has detrimental effects on birth outcome, childhood cognition and long-term behavior. Studies in animals have established a link between prenatal exposure to synthetic glucocorticoids and alterations in fetal development as well as changes in placental function. These developmental alterations appear to be permanent. Whether this is the case in humans awaits long-term follow-up of children enrolled in randomized controlled trials of prenatal glucocorticoid therapy. The research challenges in this field are now centered on uncovering the mechanisms by which glucocorticoids are involved in programming the fetus for its future life, and discovering ways in which the effectiveness and safety of antenatal glucocorticoids can be enhanced. The purpose of this mini-review is to provide a background into the use of antenatal synthetic corticosteroids and to highlight and summarize recently published clinical and animal-based studies.

Predictors of body mass index and associations with cardiovascular risk factors in Australian children: a prospective cohort study

OBJECTIVE

To examine predictors of body mass index (BMI) at the age of 8 y in a prospective study of Australian children.

DESIGN

Longitudinal survey of a cohort of Australian children followed from the 16th week of gestation to 8 y.

SUBJECTS

In total, 741 boys and 689 girls who attended the survey as 8 y olds.

MEASUREMENTS

Weight and height, blood pressure measured by automated oscillometry, fasting blood lipids and glucose. Questionnaire assessment of activity and diet.

RESULTS

Proportions of overweight including obesity in boys and girls were, respectively, 22 and 25% at 1 y, 14 and 14% at 3 y, 13 and 18% at 5 y and 15 and 20% at 8 y. At the age of 1, 3, 6 and 8 y, children with overweight including obesity showed significantly more adverse cardiovascular risk factors. Blood pressure (BP) was significantly higher by 2/3 mmHg (systolic/diastolic) at 1 y, 3/2 mmHg at 3 y, 4/2 mmHg at 5 y and 6/2 mmHg at 8 y; HDL was significantly lower (P=0.002) by 8% and triglycerides were significantly higher by 27% (P<0.001). In multivariate regression, BMI at the age of 8 y was significantly predicted positively by birth weight, mother's BMI and hours spent in watching television at the time of the survey of 6 y olds. Mothers being ex-smokers or non smokers and children being 'slightly active' and 'active' negatively predicted BMI in 8 y olds. In a subset of 298 children with information about fathers, paternal BMI was an additional independent predictor. Maternal or paternal overweight including obesity each independently increased risk of overweight including obesity at the age of 8 y three-fold. A food factor with consumption of cereals and breads as the major components derived from a Food Frequency Questionnaire in a subset of 340 children was also an independent negative predictor of BMI in multivariate models.

CONCLUSION

The increasing rate of overweight including obesity, particularly in girls, is associated with an increase in cardiovascular risk factors very early in life. Improvement of health-related behaviours within the family and a focus on promotion of activity in children should be priorities in achieving weight control.

007.Recent advances in understanding and preventing pre-term birth - the oral health connection

Pre-term birth remains one of the major unsolved problems in human health. The incidence is increasing in many Western countries, despite several decades of research studies aimed at findings ways that early birth may be prevented. Nearly two-thirds of very early pre-term births are associated with features of inflammation in the newborn, suggesting that infection may be the origin. Many studies have focussed on the possibility that pre-labour rupture of membranes or the early onset of uterine activity may result from infection spreading upward from the vagina. Unfortunately, trials designed to identify potential pathogens in the genital tract followed by appropriate use of antibiotics have failed to prevent prematurity. The strong association between features of intra-uterine inflammation and pre-term birth, and the ineffectiveness of antibiotics to prevent the problem, suggest that the source of inflammation may be from a distant site. We are addressing the possibility that the site may be the gums. Periodontal disease affects 15% of the adult Australian population, is often undiagnosed and is not responsive to systemic antibiotic therapy. In our pregnant population, we have shown that periodontal disease is strongly associated with low birth weight. Our sheep studies have taught us that the lipopolysaccharides (LPS) from periodontal pathogens, when injected into the amniotic cavity, have much greater lethality than enteric LPS, and similar effects in inducing inflammation. We are now investigating the effects of treating periodontal disease during mid-pregnancy in a randomised controlled trial, which aims to screen approximately 5000 pregnant women and allocates those with periodontal disease to treatment during pregnancy or soon after. This study is known as the Smile Study and commenced in February 2005. Improving oral health is an exciting, but yet unproven, strategy by which a major health problem may be prevented by a relatively simple and community-based intervention.

Repeated maternal glucocorticoid administration and the developing liver in fetal sheep

Prenatal glucocorticoid exposure has been associated with a reduction in birth weight and postnatal alterations in glucose homeostasis and hypothalamic-pituitary-adrenal (HPA) axis function. The mechanisms underlying these responses are unknown, although changes in fetal hepatic development may play an important role. The fetal liver produces key regulators of fuel metabolism and of the developing HPA axis that are altered by glucocorticoids. The local availability of glucocorticoids is regulated, in part, by corticosteroid-binding protein (CBG), glucocorticoid receptors (GR) and by the enzyme 11beta-hydroxysteroid dehydrogenase (11betaHSD), but the effects of maternal glucocorticoid administration on the expression of these genes in the fetal liver are unknown. 11betaHSD1 is the predominant form of this enzyme present in the liver and is responsible for the conversion of cortisone to cortisol. To determine if prenatal glucocorticoid exposure alters fetal hepatic regulation of CBG, 11betaHSD1 and GRs, we treated pregnant ewes with betamethasone (0.5 mg/kg) intramuscularly at 104, 111 and 118 days of gestation (term 150 days). Animals were killed at 125 or 146 days of gestation. Maternal betamethasone administration did not alter mean cord plasma glucose but significantly decreased cord plasma insulin levels (P<0.05) at 125 days of gestation. At 146 days of gestation, cord plasma glucose levels were significantly increased without alterations in insulin levels following maternal betamethasone treatment (P<0.05). Maternal betamethasone administration resulted in a significant increase in fetal hepatic 11betaHSD1 mRNA and protein levels at 125 days of gestation (P<0.05). CBG mRNA levels were significantly elevated over control at 125 days although levels of CBG protein were not significantly different. GR protein levels were not statistically different at either 125 or 146 days of gestation following glucocorticoid administration. These data suggest that prenatal betamethasone exposure in the ovine fetus results in alterations in cord glucose and insulin levels as well as alterations in hepatic 11betaHSD1 mRNA and protein expression. These changes in 11betaHSD1 increase the potential to generate local cortisol from circulating cortisone. We speculate that this could affect expression of glucocorticoid-dependent hepatic enzymes involved with the regulation of glucose production and HPA responsiveness.

Prenatal ultrasound biometry related to subsequent blood pressure in childhood

STUDY OBJECTIVE

To relate measures of fetal growth/size other than birth weight with subsequent blood pressure measured on the same individuals within the context of the "fetal origins of adult disease".

DESIGN

A prospective cohort study in which measurements of fetal dimensions obtained by serial ultrasound imaging between 18 and 38 weeks gestation were analysed with reference to systolic blood pressure measurements on the offspring at age 6 years.

SETTING

Perth, Western Australia.

PARTICIPANTS

A subgroup of 707 eligible mother-fetus pairs from a cohort of 2876 pregnant women and their offspring. The number of mother-fetus pairs varied at each gestational age and by measurement of fetal dimension. Subsequent blood pressure recordings were obtained on approximately 300 of the offspring at age 6 years.

MAIN RESULTS

The findings confirmed the inverse association between birth weight and systolic blood pressure at age 6. There was, also, an inverse relation between fetal femur length and systolic blood pressure at age 6, adjusted for current height. Furthermore, an inverse association was demonstrated between a statistically derived measure of fetal growth (conditional z score) between 18 and 38 weeks gestation and later systolic blood pressure at age 6. The effect sizes for all three relations were in the order of 1-2 mm Hg per standard deviation change.

CONCLUSION

The mechanisms underpinning the "fetal origins" hypothesis may be operative early in pregnancy and may be reflected in the length of the fetal femur in early to mid-pregnancy.

The effects of overcoming experimental bladder outflow obstruction in fetal sheep

OBJECTIVE

To develop an ovine model of fetal bladder outflow obstruction and to investigate the effect on the kidney of surgical relief of the obstruction in the prenatal period.

METHODS

Ultrasound examination and amniocentesis were performed on 68 date-bred pregnant ewes at day 57 of pregnancy (term = 150 days). Fetal gender was determined using a molecular technique to identify single male fetuses. The urethra and urachus were ligated at hysterotomy on 20 of these fetuses at 75 days' gestation. Comparisons were made with six controls that did not undergo operation. Changes that occurred in fetal urinary tract appearance were detected using serial ultrasound examinations. Seven obstructed cases chosen at random had further prenatal surgery on day 94 to decompress the obstructed urinary tract by vesicostomy. The animals were killed at 110 days' gestation and post-mortem studies were performed.

RESULTS

Fourteen days after surgical obstruction, there were increases in the summed renal lengths (33 mm vs. 28 mm, p = 0.003) and renal pelvis anteroposterior (A-P) diameters (8 mm vs. 5.5 mm, p = 0.02). In the group allocated to receive surgical decompression, 9 days' relief of obstruction resulted in significant reductions in summed renal lengths (30 mm vs. 41 mm, p = 0.024; controls 31 mm) and renal pelvis A-P diameters (5.8 mm vs. 8.9 mm, p = 0.012; controls < 2 mm). Postmortem histological examination in the surgical decompression group revealed an estimated number of glomeruli similar to controls and greater than in the obstructed cases.

CONCLUSION

Surgical relief of fetal bladder outflow obstruction in ovine mid-pregnancy results in improved renal appearance on ultrasonic and histopathological examinations.

The effect of prenatal betamethasone administration on postnatal ovine hypothalamic-pituitary-adrenal function

Prenatal exposure to glucocorticoids is associated with alterations in fetal growth and endocrine function. However, few studies have examined the effects of clinically relevant doses of glucocorticoids on postnatal hypothalamic-pituitary-adrenal (HPA) function. To determine the effects of maternal or fetal betamethasone administration (0.5 mg/kg maternal or estimated fetal weight) on postnatal HPA function at 6 months and 1 year postnatal age, pregnant ewes were randomized into the following treatment groups: no treatment (n=6); maternal saline (n=6); single maternal betamethasone (M1) (n=6); repeated maternal betamethasone (M4) (n=6); fetal saline (n=5); single fetal betamethasone (n=6) and repeated fetal betamethasone (F4) (n=6). Single injections were given at 104 days of gestation and repeated injections at 104, 111, 118 and 125 days. Lambs were born spontaneously and the ACTH and cortisol responses to i.v. corticotropin-releasing hormone (CRH) (0.5 microg/kg) plus arginine vasopressin (AVP) (0.1 microg/kg) were measured at 6 months and 1 year postnatally. At 6 months postnatal age, neither maternal nor fetal prenatal betamethasone administration altered significantly the ACTH and cortisol responses to CRH+AVP. However, in animals at 1 year postnatal age, a previous single injection of betamethasone to the mother (M1) resulted in significantly elevated basal and stimulated cortisol levels (P<0.05), without significant change in the ACTH response. In contrast, betamethasone administration to the fetus resulted in significantly attenuated ACTH responses to CRH+AVP at 1 year compared with control animals (P<0.05), but these were not associated with any significant changes in basal or stimulated cortisol levels. All control animals exhibited a significant increase in peak ACTH responses to CRH+AVP between 6 months and 1 year postnatal age (P<0.05). After prenatal betamethasone (F4, M4) the difference in peak ACTH response between animals at 6 months and 1 year postnatal age was abolished. We conclude that in sheep between 6 months and 1 year postnatal age, HPA function undergoes developmental changes that are influenced by prenatal glucocorticoid exposure. Furthermore, the effects of glucocorticoid on postnatal HPA responses may vary according to the time in gestation that the steroid was administered, and whether it was given directly into the fetal or maternal compartment.

Statistical measures of foetal growth using linear mixed models applied to the foetal origins hypothesis

Statistical models of the relationship between the distribution of each of five foetal dimensions and gestational age are developed based on serial ultrasound biometric data from a prospective longitudinal study in Perth, Western Australia. Both the response variable and the gestational age timescale are transformed to establish an approximately linear relationship within subjects. This relationship is modelled using a linear mixed effects model that accounts for between-subject heterogeneity by incorporating subject specific random effects for both intercept and gradient. These models are used to motivate three measures of foetal growth: the conditional centile or z-score of a current measurement given an earlier value for the same measurement; the best linear unbiased predictor (BLUP) of the subject specific random effect gradient (which is shown to be invariant to transformations of location and scale), and the standardized residual at a given gestational age, which characterizes departures from the modelled growth trajectory. We illustrate how these three measures of growth might be applied to subsequent health outcomes in later life by relating growth in foetal abdominal circumference to blood pressure in children from the same cohort at six years of age. Foetuses whose summary measures indicate poor growth in abdominal circumference have higher blood pressure in early childhood, supporting the 'foetal origins' hypothesis that many chronic diseases of adulthood have their origins before birth.

Is prenatal glucocorticoid administration another origin of adult disease?

1. The intra-uterine environment is now believed to play a major role in the origin of many adult diseases. Illnesses in which there is significant 'programming' before the time of birth include hypertension, diabetes, coronary heart disease and stroke. Acting on a genetic predisposition, intra-uterine triggers appear to programme the individual's metabolism and endocrine milieu and, after birth, these risk factors are then either amplified or minimized by environmental influences. The triggers operative during fetal life that have been studied most extensively are undernutrition and glucocorticoid exposure. 2. Over the past decade, a series of studies in sheep have focused on the perinatal and life-long consequences of glucocorticoid exposure in mid- to late-pregnancy. These studies in the sheep model have shown that maternal injections with glucocorticoids, in a manner similar to clinical treatment for women at risk of preterm birth, enhance fetal lung maturation, but were also associated with developmental and other functional alterations that are of concern. With weekly doses to the mother, there is restricted fetal growth, delayed myelination of the central nervous system, altered blood pressure soon after birth and increased insulin response to glucose challenge in early adulthood. If the glucocorticoids are given to the fetus by ultrasound-guided intramuscular injection, rather than to the mother, the effects on lung maturation are similar, but growth is spared and blood pressure after birth is unaltered. Increased insulin response to glucose challenge occurs in early adulthood with glucocorticoid by either route and is independent of growth restriction. 3. The findings in experimental animals are supported by studies of children in the Western Australian Preterm Infant Follow-up Study. Multivariate analyses have shown that increasing the number of glucocorticoid exposures, for the purpose of enhancing lung maturation prior to preterm birth, is associated with reduced birthweight and behavioural disorders at 3 years of age. 4. The results of these animal and clinical studies provide further support for a role of prenatal glucocorticoid exposure in triggering predisposition to adult disease. Further exploration of these models is expected to uncover the mechanisms and lead to effective strategies that may underpin clinical interventions.

Repeated ultrasound guided fetal injections of corticosteroid alter nervous system maturation in the ovine fetus

INTRODUCTION

Recent studies in sheep have shown that repeated maternal injections of betamethasone are associated with adverse effects within the nervous system. Repeated fetal injections of betamethasone achieve serial improvements in preterm lung function in sheep and are a possible alternative to repeated maternal therapy. We have evaluated the effect of repeated fetal administration of betamethasone on nervous system maturation in an ovine model.

METHODS

Date-mated ewes (n = 48) were randomized to receive ultrasound-guided fetal injections of betamethasone or saline between days 104 to 124 of gestation and were delivered by cesarean section on day 125 or 145 (term = 150). Optic and sciatic nerves were prepared for light and electronmicroscopy. Eye diameters were measured and transverse sections of retinae were evaluated. Data were analyzed using a mixed model analysis of variance.

RESULTS

Repeated fetal administration of corticosteroid did not significantly affect optic nerve myelination but resulted in significant delays in sciatic axonal growth (p < 0.02) and retinal maturation (p < 0.04). The process of performing repeated fetal injections also significantly affected some retinal parameters.

CONCLUSION

Repeated fetal administration of betamethasone alters some aspects of nervous system maturation in sheep. It is premature to plan trials of repeated fetal corticosteroid therapy in humans.

Dose and time response after intraamniotic endotoxin in preterm lambs

Intraamniotic endotoxin causes chorioamnionitis, which is followed by improved fetal lung function after 4 d in fetal sheep. We evaluated 0.1 mg, 1 mg, 4 mg, and 10 mg endotoxin for inflammation and lung maturation effects after 7 d. Four and 10 mg endotoxin caused similar lung maturation and inflammation in the lung and chorioamnion. The number of neutrophils in cord blood and the inflammatory cells in alveolar lavage and fetal lung tissue increased in a dose-dependent manner. Lower endotoxin doses induced indicators of chorioamnionitis, lung and systemic inflammation without inducing lung maturation. Therefore, some degree of inflammation can occur without subsequent lung maturation. The inflammatory changes caused by 4 mg endotoxin were assessed after 5 h, 24 h, 72 h, and 7 d to discern local versus systemic inflammation after intraamniotic endotoxin. At 5 h active inflammatory cells were in the airways producing hydrogen peroxide, and interleukin-6 and -8 were increased in the cord blood indicating both lung and systemic responses. Cells recruited into the amniotic fluid produced proinflammatory cytokine mRNA for 7 d with no cytokine mRNA in chorioamnion, lung, or spleen after 72 h. The cells in the amniotic fluid may be a source of prolonged fetal exposure to proinflammatory cytokines.

Programming effects in sheep of prenatal growth restriction and glucocorticoid exposure

Our aim was to determine the postnatal effects of single and repeated glucocorticoid injections during late gestation. Repeated (104, 111, 118, 125 days) or single (104 days) injections of betamethasone or saline were given to the ewe or by ultrasound guided injection to the fetus (term 150 days). Lambs were born spontaneously and studied at 3 and 6 mo and 1 yr of age. Arterial pressure was measured at each age, and we performed intravenous glucose tolerance tests at 6 mo and 1 yr. Repeated maternal, but not single maternal or fetal, betamethasone injections prolonged gestation, reduced weight at birth and 3 mo, and was associated with low arterial pressure at 3 mo but not at 6 mo and 1 yr. Glucose metabolism was altered in all betamethasone treatment groups, regardless of the number or route of injections. Our data demonstrate that glucocorticoid-induced fetal growth restriction is associated with a transient reduction in postnatal arterial pressure, but glucocorticoid exposure with or without growth restriction alters glucose metabolism.

Repeated prenatal corticosteroid administration delays astrocyte and capillary tight junction maturation in fetal sheep

Glucocorticoids are powerful regulators of cell differentiation and maturation. Their synthetic counterparts, the corticosteroids, are used widely in obstetric practice to enhance fetal lung maturation in cases of threatened preterm birth. Here we examined the effects of repeated corticosteroid administration on astrocyte and capillary tight junction development in the fetal sheep brain, selecting the corpus callosum for analysis. Pregnant ewes were given saline or betamethasone (0.5 mg/kg) at 104, 111, 118 and 124 days gestation. Lambs were delivered at term, terminally anaesthetized and transcardially perfused. Transverse semi-thin sections of the corpus callosum were cut and immuno-stained with antibody against glial fibrillary acidic protein (GFAP). Ultra-thin sections were examined in the electron microscope. The percentage area of GFAP staining was reduced in the corticosteroid-treated group compared to control (5.2 vs. 8.7%, P<0.05). The expression of GFAP in peri-capillary and parenchymal astrocytes was also reduced compared to control (peri-capillary: 3.0 vs. 9.5 microm2; parenchymal: 14.6 vs. 29.4 microm2, P<0.05). Furthermore, capillary tight junction maturation was delayed compared to control. Immature 'type II' junctions were more common in the corticosteroid-treated group (63 vs. 22%, P<0.05), whereas more mature 'type III' junctions were less common (27 vs. 65%, P<0.05). Our data suggest that repeated corticosteroids delay both astrocyte and capillary tight junction maturation. The implications for clinical practice are as yet unknown.

Antenatal glucocorticoids and growth: single versus multiple doses in animal and human studies

In recent years, many clinicians have prescribed repeated courses of glucocorticoids to pregnant women at risk of early preterm birth. The published literature has provided reassurance from randomized controlled trials that single-course treatment improves postnatal lung function without deleterious consequences, but we do not yet have data from randomized trials designed specifically to investigate the effects of repeated courses. Data from animal studies have, for many years, provided evidence that prenatal exposure to glucocorticoids restricts fetal growth and, more recently, has suggested a role in programming the individual to adult disease. Multivariate analyses from non-randomized cohorts have also suggested associations between repeated treatments and reduced birth weight, but we await results from randomized controlled trials currently in progress to provide more definitive answers. Regardless of any effect on growth, the possibility that adult health and disease may be programmed by fetal exposure to glucocorticoids will ensure our need to balance the ability of these agents to improve newborn survival with the potential consequences in later life.

The interactive effects of endotoxin with prenatal glucocorticoids on short-term lung function in sheep

OBJECTIVE

Previously we have shown that neonatal lung function in sheep after preterm birth is profoundly enhanced by intra-amniotic injection of endotoxin, with a magnitude at least equal to that induced by maternal betamethasone administration. This study investigated the effects of betamethasone on lung maturation and growth in the presence of inflammation by treating sheep with both maternal intramuscular betamethasone and intra-amniotic endotoxin injections.

STUDY DESIGN

Time-mated pregnant ewes at 118 days' gestation were allocated at random to receive maternal intramuscular or intra-amniotic saline solution injection (n = 10), maternal intramuscular betamethasone injection (0.5 mg/kg; n = 7), intra-amniotic endotoxin injection (20 mg Escherichia coli B055;B5; n = 11) by ultrasonographic guidance, or both betamethasone and endotoxin injections (n = 7). The lambs were delivered abdominally at 125 days' gestation (term is 150 days' gestation), and the neonates were ventilated for 40 minutes before postmortem examination.

RESULTS

Combined treatment with betamethasone and endotoxin resulted in significantly greater improvements in neonatal lung function than occurred after treatment with either agent alone, and this effect was not accompanied by a further increase in surfactant levels. The reduction in birth weight that is seen after maternal betamethasone treatment was not seen when this treatment was combined with endotoxin. Endotoxin treatment resulted in inflammatory responses in cord blood and alveolar wash, and these responses were not inhibited by betamethasone treatment. There were no pregnancy losses.

CONCLUSION

Both intra-amniotic endotoxin injection and maternal intramuscular betamethasone injection promoted fetal lung maturation. When these treatments were combined, there were additive effects on short-term postnatal lung function but not on surfactant levels. Endotoxin negated the growth restriction in sheep caused by maternal betamethasone treatment. These findings provide evidence that the lung maturation induced by glucocorticoids and that induced by endotoxin are mediated by different mechanisms.

Repeated prenatal corticosteroid administration delays myelination of the corpus callosum in fetal sheep

Glucocorticoids regulate oligodendrocyte maturation and the myelin biosynthetic pathways. Synthetic glucocorticoids, the corticosteroids have been successfully used in clinical practice as a single course to enhance lung maturation and reduce mortality and morbidity in preterm infants with no long-term neurologic or cognitive side effects. However, a trend has arisen to use repeated courses despite an absence of safety data from clinical trials. We examined the effects of clinically appropriate, maternally administrated, repeated courses of corticosteroids on myelination of the corpus callosum using sheep as a large animal model. The corpus callosum is a major white matter tract that undergoes protracted myelination, underpins higher order cognitive processing and developmental damage to which is associated with, for example, cerebral palsy, mental retardation and attention deficit hyperactivity disorder. Pregnant ewes were given saline or betamethasone (0.5 mg/kg) at 104,111,118 and 124 days gestation, stages equivalent to the third trimester in humans. Lambs were delivered at 145 days (term), perfused and the corpus callosum examined light and electron microscopically. Total axon numbers were unaffected (P>0.05). However, myelination was significantly delayed. Myelinated axons were 5.7% in the experimental group and 9.2% in controls (P<0.05); conversely, unmyelinated axons were 88.3 and 83.7% (P<0.05). Myelinated axon diameter and myelin sheath thickness were also reduced (0.68 vs. 0.94 and 0.11 vs. 0.14 microm, P<0.05). Our data suggest that repeated prenatal corticosteroid administration delays myelination of the corpus callosum and that further safety data are needed to evaluate clinical practice.

Placental weight and placental ratio as predictors of later blood pressure in childhood

OBJECTIVE

A significant inverse relationship between blood pressure and birth weight is firmly established. This association may be the result of fetal adaptations to an adverse intrauterine environment. Further markers of intrauterine growth include the weight of the placenta and the placental ratio (the ratio of placental weight to birth weight). A number of studies suggest that a decreased placental weight or an elevated placental ratio may be independent risk factors for subsequent high blood pressure. The overall evidence for this is, however, inconclusive. The purpose of the present study was to clearly define the relationships between placental weight, placental ratio and subsequent blood pressure during childhood.

DESIGN

Prospective cohort study of 2507 singleton children, born at term during 1989-1992. Blood pressures were recorded at ages 1, 3 and 6 years, using a semi-automated oscillometric device.

RESULTS

Inverse relationships existed between both systolic and diastolic blood pressure and placental weight, adjusted for current weight at ages 1, 3 and 6 years. The relationships between placental weight and systolic blood pressure were statistically significant at ages 1 and 3 years. There was no consistent relationship between placental weight and later blood pressure within birth weight categories. No clinically or statistically significant association was seen between the placental ratio and either systolic or diastolic blood pressures at any age.

CONCLUSIONS

Birth weight, rather than placental weight or their ratio, is the early life factor most importantly related to subsequent blood pressure in childhood.

Endotoxin-induced lung maturation in preterm lambs is not mediated by cortisol

Antenatal exposure to glucocorticoids, amnionitis, intraamniotic interleukin (IL)-1alpha, or endotoxin can improve postnatal lung function after preterm delivery. The relationship between early lung maturation and the dose and duration of a proinflammatory stimulus has not been evaluated. The effects of proinflammatory stimuli on fetal plasma cortisol also have not been evaluated. We hypothesized that intraamniotic endotoxin would induce early lung maturation in fetal sheep without increasing fetal cortisol. Intraamniotic injections of 1, 4, 20, or 100 mg of Escherichia coli 055:beta5 endotoxin caused 2-fold increases in compliance, 4- to 5-fold increases in lung gas volumes, and 20-fold increases in alveolar saturated phosphatidylcholine (Sat PC) when given 7 d before preterm delivery at 125 d gestation. Animals treated with 20 mg endotoxin for treatment to delivery intervals of 5 h to 15 d had no significant elevations in cord plasma cortisol levels. Increases in Sat PC in lung tissue and alveolar washes were detected 2 d after endotoxin treatment and lung function improved 4 d after endotoxin treatment. Two doses of endotoxin given 3 and 7 d or 7 and 15 d before treatment resulted in lung maturation responses equivalent to single dose comparison groups without elevations in cortisol. Early lung maturation induced by intraamniotic endotoxin in fetal sheep occurred without an increase in fetal plasma cortisol, indicating that endotoxin promoted lung maturation by a mechanism independent of cortisol.

Adjustment for current weight and the relationship between birth weight and blood pressure in childhood

OBJECTIVE

To determine the role of current weight in mediating the relationship between birth weight and blood pressure within the context of the 'fetal origins' hypothesis.

DESIGN

Prospective cohort study of 2507 pregnant women and their singleton offspring, delivered live at term, in Perth, Western Australia between 1989 and 1992. The study commenced at 16 weeks gestation with serial weight and blood pressure measurements recorded through early childhood.

RESULTS

Inverse associations were found between birth weight and systolic blood pressure at ages 1, 3 and 6. The effect of birth weight on systolic blood pressure at age 6 reached statistical significance and was increased fourfold in magnitude to -2.3 mmHg [95% confidence interval = (-3.3 to -1.3), P < 0.01] after adjustment for current weight. The interaction term for birth weight and current weight was not statistically significant. Including intermediate weights did not produce a statistically significantly better model but did increase the magnitude of the estimated regression coefficient of birth weight on blood pressure, and only the birth weight and current weight terms were significant

CONCLUSIONS

Adjustment for current weight serves to highlight the relationship between birth weight and blood pressure in childhood. Nevertheless, birth weight, rather than birth weight adjusted for current weight, is still the relevant predictor of later blood pressure within the context of the 'fetal origins' hypothesis.

Fetal sciatic nerve growth is delayed following repeated maternal injections of corticosteroid in sheep

AIMS

A single course of prenatal corticosteroid reduces the mortality and morbidity of preterm birth. Repeated courses of prenatal corticosteroids are widely prescribed despite a lack of safety data. Repeated corticosteroids delay myelination in the ovine central nervous system at the time of preterm delivery but with catch-up at term. We aimed to evaluate their effect in the peripheral nervous system.

METHODS

Thirty date-mated ewes were administered either saline, a single injection of betamethasone, or four injections of betamethasone between 104 and 124 days' gestation, with delivery on day 125 or 145 (term = 150 days). Sciatic nerves were dissected and fixed in modified Karnovsky's fixative and prepared for light and electron microscopy to determine the proportion of myelinated axons and mean axon diameter.

RESULTS

Repeated, but not single, corticosteroid administration resulted in significant decreases in the total cross-sectional and fascicle-containing areas of the sciatic nerve, and in the mean diameter of myelinated and unmyelinated axons. Deficits persisted at term. The proportion of myelinated axons was unaffected.

CONCLUSION

Repeated prenatal corticosteroids have the capacity to affect the growth of peripheral nerve axons in sheep. Documentation of their effects in human pregnancy await randomized trials.

Effects of repeated maternal betamethasone administration on growth and hypothalamic-pituitary-adrenal function of the ovine fetus at term

Synthetic glucocorticoids have become an important clinical tool with which to advance fetal lung maturation in women at risk of early preterm birth, and this has succeeded in reducing neonatal mortality and morbidity from respiratory distress syndrome. Although previous studies have shown that glucocorticoids have deleterious consequences on fetal development, there is little information regarding the effects of clinically relevant repeated maternal doses of glucocorticoids on fetal growth and hypothalamic-pituitary-adrenal (HPA) function. We hypothesised that repeated prenatal exposure to increased concentrations of glucocorticoids would alter fetal growth and HPA axis development. Pregnant ewes were injected with betamethasone (0.5 mg/kg) or vehicle at 104, 111 and 118 days of gestation (term 150 days). Animals were sacrificed at 125 and 146 days of gestation, at which time fetal weights were recorded. Maternal and fetal blood samples were gathered and fetal tissue collected. Maternal oestradiol concentrations were significantly greater than those in controls at 125 days of gestation, but were not different at 146 days. Maternal plasma progesterone concentrations were similar between groups at both 125 and 146 days of gestation. Weight at birth was significantly reduced by 23% at 125 days and 19% at 146 days of gestation (P<0.05) after exposure to glucocorticoid. Cord plasma ACTH concentrations were not significantly different between groups at day 125, but were significantly increased in day 146 fetuses of ewes that had received betamethasone (P<0.05). Cord plasma cortisol concentrations followed the same trend, although differences were not statistically significant. Cord plasma corticosteroid binding capacity (CBC) was significantly increased at 125 days of gestation in fetuses of betamethasone-treated animals (P<0.05), but not at 146 days of gestation. To examine the mechanisms regulating the increase in cord plasma ACTH of 146-day fetuses, we used in situ hybridisation to determine the distribution and levels of mRNA encoding key pituitary and hypothalamic neuropeptides of the HPA axis. In pituitaries of 146-day fetuses, there were no significant differences in the regional pattern of distribution or amounts of pro-opiomelanocortin (POMC) mRNA between betamethasone-treated animals and controls, in either the pars intermedia or the inferior and superior regions of the pars distalis. Neither prohormone convertase (PC)-1 nor PC-2 mRNA levels in pituitaries of 146-day fetuses were significantly different between treatment groups. After maternal betamethasone, immunoreactive ACTH peptide content in the fetal pars distalis was not different but glucocorticoid receptor (GR) mRNA levels in the pars distalis were increased significantly (P<0.05). No significant difference in distribution pattern or concentrations of corticotrophin-releasing hormone (CRH) mRNA, GR mRNA, oxytocin mRNA and pre-proenkephalin mRNA were found in hypothalami from fetuses at 146 days of gestation after betamethasone treatment. We conclude that antenatal betamethasone given to pregnant sheep in a manner similar to that used in human obstetric practice results in reduced weight at birth at 125 and 146 days, and altered basal cord levels of plasma ACTH and corticosteroid binding capacity, but these changes are not reflective of changes in steady state concentrations of POMC and CRH mRNA in the fetal pituitary or hypothalamus.

Effects of antenatal endotoxin and glucocorticoids on the lungs of preterm lambs

OBJECTIVE

We hypothesized that the proinflammatory response to intra-amniotic endotoxin would induce lung maturation in preterm lambs.

STUDY DESIGN

Ewes were randomly assigned to receive 20 mg Escherichia coli endotoxin by intra-amniotic injection, maternal betamethasone (0.5 mg/kg), or sodium chloride solution. Preterm lambs were delivered at 125 days' gestation and underwent ventilation to assess lung function. Lung gas volume, surfactant concentrations, and inflammation were subsequently evaluated, with data analyzed by analysis of variance.

RESULTS

Fetal endotoxin exposure 6 days before delivery increased compliance by 59%, increased lung gas volume 2.3-fold, increased concentrations of surfactant lipids, increased surfactant A and B protein levels, and increased messenger ribonucleic acid expressions for surfactant proteins (all P <.01, vs control group). Betamethasone exposure resulted in less consistent effects. White blood cell counts were increased in fetal membranes and lungs after endotoxin exposure, but there was no severe inflammation.

CONCLUSION

A single fetal exposure to endotoxin resulted in large improvements in postnatal lung function and increases in surfactant concentrations after preterm delivery. These effects were qualitatively larger than those achieved with betamethasone.

Retinal maturation is delayed by repeated, but not single, maternal injections of betamethasone in sheep

PURPOSE

The safety and efficacy of prescribing a single maternal course of corticosteroid during pregnancy has been documented in human trials. However, the current trend is to prescribe repeated courses of corticosteroid. We investigated an aspect of the safety of this practice in an animal model.

METHODS

Date-mated ewes received saline, single or four corticosteroid injections between days 104 and 124 of gestation (term = 150). Lambs were delivered on day 125 or 145 by caesarian section after spinal anaesthesia. Eye diameters were measured and semi-thin toluidine-blue-stained transverse sections of retinae were analysed using an Optimus Image Analysis program.

RESULTS

At 125 days, retinal measures in the ventral periphery and area centralis were significantly thinner than control (p = 0.0001). At 145 days, total eye size was significantly reduced compared with control (p = 0.03), and retinal measures in the ventral periphery (p = 0.0001), but not the area centralis (p = 0.19), remained significantly different from control.

CONCLUSION

Repeated maternal administration of corticosteroid may affect retinal maturation in the fetus.

Maternal cigarette smoking during pregnancy, low birth weight and subsequent blood pressure in early childhood

Given the widely acknowledged inverse relationship between birth weight and blood pressure, a raised blood pressure in the offspring of smoking mothers as compared to those whose mothers did not smoke, would be anticipated by virtue of the reduction in birth weight associated with smoking during pregnancy. The objective of the present study was to test the hypothesis that maternal cigarette smoking during pregnancy has an effect on blood pressure in childhood independent of its effect on birth weight. Data was obtained from a prospective cohort study of 1708 pregnant women and their singleton offspring, delivered live at term, in Perth, Western Australia, commenced at 16 weeks gestation with serial blood pressure measurements through early childhood. Statistically significant associations were found between maternal smoking during pregnancy and systolic blood pressure at age six, between birth weight and systolic blood pressure at ages three and six, and between maternal smoking during pregnancy and birth weight. The relationship between birth weight and blood pressure in early childhood differed significantly on the basis of maternal cigarette smoking or not during pregnancy. This differential relationship persisted after adjustment for the child's current weight and socio-economic status. We concluded that intra-uterine exposure to maternal cigarette smoking increased children's blood pressure at age one through to age six. This was not wholly attributable to an effect on birth weight or confounding of the association between birth weight and subsequent blood pressure by the child's current weight or socio-economic factors. Furthermore, maternal smoking during pregnancy does not account for the acknowledged elevation in blood pressure associated with low birth weight. The present study is an exploration of a possible causal pathway underlying the birth weight/blood pressure association rather than simply a confirmation of such an association which has been detailed in many other papers.