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Biomedical subjects

B S Ward

Publications and source records attributed to B S Ward.

At least 19 recordsLinked to original sources
PubMed2007

Perinatal outcome of quadruplet pregnancies in relation to chorionicity.

OBJECTIVE: To compare the perinatal outcome of quadruplets in relation to chorionicity. PATIENTS AND METHODS: In this retrospective study, the maternal, neonatal and chorionicity data were collected from 24 sets of quadruplet pregnancies delivered between January 1985 and December 2001. Perinatal and neonatal data were evaluated in relation to chorionicity. RESULTS: Sixteen pregnancies were quadra-chorionic quadramniotic (QC) and eight had at least one monochorionic pair (TC). The median gestational age at delivery was 31 weeks (23 to 34 weeks) with overall perinatal mortality rate of 177 per 1000 total birth. Delivery before 30 weeks (OR 89; 95% CI 9 to 607; P<0.01) and discordant birth weight of >25% (OR 7.6; 95% CI 2 to 29; P<0.01) had independent effects on perinatal loss rate. The perinatal loss was five fold higher in TC quadruplets than those of QC (OR 5.1; 95% CI 1.7 to 15.4; P<0.001). This was attributed to higher risk of very low birth weight (69 vs 13%; P<0.01), delivery before 30 weeks (63 vs 13%; P<0.001) in TC quadruplets compared to QC gestation. CONCLUSIONS: The quadruplets with MC pair have 5 times higher perinatal mortality than quadra-chorionic quadruplet pregnancies owing to preterm delivery and discordant birth weight.

Birth Weight↗
PubMed2006

Artificial perfusion of the fetal circulation of the in situ mouse placenta: methodology and validation.

Here we present methodology and validation (including measurement of unidirectional maternofetal clearance (Kmf) of (45)Ca and (14)C-mannitol) for in situ perfusion of the mouse placenta. On day 18 of gestation (term=19 days) mice were anaesthetised and the uterus delivered into a saline bath (40 degrees C). A fetus was selected, the umbilical artery and vein catheterised and perfused with Krebs Ringer (pH 7.4) at 60 microl/min. (45)Ca/(14)C-mannitol (2 microCi/5 microCi in 50 microl saline) was injected via maternal tail vein. Perfusate samples were collected every 5 min for 45 min. Maternal carotid artery pressure was monitored throughout perfusion. A terminal maternal cardiac blood sample was taken and analysed. Placentas were immersion fixed and processed for electron microscopy. Kmf for (45)Ca and (14)C-mannitol was calculated as perfusate [(45)Ca or (14)C-mannitol] x perfusion rate/maternal plasma [(45)Ca or (14)C-mannitol]xplacental weight. Maternal cardiac blood chemistry at termination (n=8-15, mean+/-SEM) was as follows: pH 7.153+/-0.016, PCO(2) 45.48+/-2.06 mmHg, PO(2) 66.47+/-7.10 mmHg, Na(+) 151.4+/-1.2 mmol/l, K(+) 5.54+/-0.17 mmol/l, Ca(2+) 1.15+/-0.03 mmol/l, glucose 7.2+/-0.5 mmol/l, and lactate 1.76+/-0.77 mmol/l. A successful 45 min perfusion in which perfusate recovery was >95% occurred in >50% of animals. Perfusion did not alter placental morphology or carotid pressure. Kmf (microl/min/g placenta) for (45)Ca (66.0+/-8.4 (n=7)) was significantly higher than Kmf for (14)C-mannitol (20.0+/-2.4 (n=5)) (p<0.01). These data demonstrate physiological perfusion of the mouse placenta in situ and its usefulness for measurement of solute transfer.

Animals↗
PubMed2005

Electrical potential difference between mother and conceptus in the mouse.

This study aimed to determine whether there is a maternofetal potential difference (PD) in the mouse. The mean (+/- SEM) in vivo electrical potential difference (PD(sa)) between saline filled catheters in the maternal subcutaneous space (s) and the fetal amniotic sac (a) measured, according to strict criteria, in anaesthetised MF1 mice at a gestational age of 18-20 (term 20) days was 3.9+/-0.5 mV (significantly different from zero P<0.0001) in 16 conceptuses from 11 mice with the amniotic sac positive with respect to the maternal catheter. The PD(sv) between maternal tail vein (v) and maternal subcutaneous space was -0.8+/-0.4 mV (n=3: not significantly different from zero). Measurement of PD between two different maternal subcutaneous catheters (n=4) was < or =0.5 mV. This study shows that there is a maternofetal PD in the mouse and provides the foundation for studies addressing its mechanism of generation in this species.

Amniotic Fluid↗
PubMed2000

Attention to infants in the first year.

The time spent by 158 infants in contact with their carers at 6, 13, 26 and 52 weeks was reviewed prospectively. Periods of contact in the categories of (1) physical care, (2) holding the crying or sleeping infant, and (3) playing and interacting with the infant were recorded using 24-h log diaries completed by the mother. The mean total carer contact time over a 24-h day did not change significantly in the first year, varying between 6.5 and 73 h. Between 6 and 52 weeks, time spent by the mother in physical care declined significantly from 207 to 143 min and in holding the crying or sleeping infant from 61 to 17 min (P < 0.05 and 0.0001 respectively). There were no significant changes in the amount of time spent in playing and interacting with the infant over the first year by the mother and father, the time being on average 52.7 and 25.0 min respectively. Play and interaction with a non-parental carer increased significantly from 14 to 69 min (P < 0.0001). Relationships between infant size and holding became weaker as the infant became older. Infant gender, socioeconomic status and duration of breast-feeding did not influence infant contact time.

Analysis of Variance↗
PubMed1998

Site of catecholamine modulation of feto-maternal electric potential difference in the pig.

Feto-maternal vascular (PD(F-M)) and amniotic maternal (PD(A-M)) potential differences were measured simultaneously on seven occasions in six conscious pigs of 100-106 days gestation. Resting values of PD(F-M) and PD(A-M) were not significantly different although the range was wide. Fetal intravascular injection of 20 microg adrenaline, but not of saline, was associated with a prompt reversible change, of equal magnitude, in both PD(F-M) and PD(A-M). In some experiments polarity was reversed. Feto-amniotic potential difference did not change. There was no change in fetal plasma K+ and Na+ concentrations. Because of the simultaneous and equal alterations in PD(F-M) and PD(A-M) following adrenaline and the anatomical configuration of the pig conceptus, we conclude that the catecholamine modifiable component of PD(F-M) is generated by electrogenesis in the pig placenta, probably by its chorionic (trophoblastic) cell layer.

Animals↗
PubMed1995

Fetal and postnatal growth to age 2 years by mother's country of birth.

The objective of this study was to measure the physical growth of fetuses and infants in an inner city health district in the north of England and to compare their growth profiles according to mother's country of birth (British Isles or Indian subcontinent). The study was part of the Central Manchester Child Growth Project, a prospective longitudinal study of fetal and postnatal growth and development in a sample from the geographically-defined Central Manchester Health District. Data were collected from the beginning of the second trimester of pregnancy to the age of 2 years. One-hundred seventy-four singleton infants born at term ( > or = 37 weeks) had serial antenatal cephalometry every 3 weeks from the beginning of the second trimester and had serial head, length and weight measurements at birth and at the ages of 6, 13, 26, 52 and 104 weeks. Infants of Indian-born mothers tended to be lighter at birth than those of locally-born mothers, but the difference was not due to lower accumulation of soft tissue. Body length from 6 to 52 weeks in both groups of infants was similar. The major finding was the reduced head size in infants of Indian-born mothers, the difference being significant among boys, evident from mid-pregnancy and persisting postnatally to age 2 years. Reduced fetal growth is associated with the development of cardiovascular disease in adulthood, mortality from ischaemic heart disease being specifically linked with head size at birth. The reduced head size of boys of Indian-born mothers is of interest because male immigrants from the Indian subcontinent who live in England have an increased incidence of non-insulin dependent diabetes and a substantial excess mortality (standardised mortality ratio 313 at ages 20-29) from ischaemic heart disease.

Bangladesh↗
PubMed1995

Duration and pattern of crying in the first year of life.

In a prospective study of fetal and postnatal growth and development in a group of babies whose mothers were residents of an inner-city health district in the north of England, the total amount of crying of 157 infants was recorded at four periods during the first year of life by means of a 24-hour log. The mean number of crying episodes reduced from 4.4 at six weeks to 1.5 at one year. Early crying predicted later crying. It was not possible to predict which babies would cry a lot except that breast-fed infants tended to cry less. Mothers' perceptions of whether their babies cried a lot correlated with their perception of sleep difficulties. Rapid response to crying was associated with significantly less crying overall.

Crying↗
PubMed1990

Sleep in the first year of life.

The sleep patterns of 174 infants were recorded on one typical day at six, 13, 26 and 52 weeks of age, using a 24-hour log. During the first year of life the number of episodes of sleep was reduced by about 50 per cent, but total sleep time was reduced by only two hours. A circadian rhythm was established by six weeks of age. Smaller infants slept more than larger ones in the first months of life. Sex or birth-order of the child did not affect the duration or number of sleep episodes, but sleep pattern related significantly to whether or not mothers found their infants difficult to feed. Introduction of weaning food at an early stage reduced the number of sleep episodes, but increased the average length of each episode. Socio-economic status showed no significant relationship with number of episodes or total length of sleep.

Circadian Rhythm↗
PubMed1989

Maternofetal potential difference in pigs.

The maternofetal potential difference (PD) between catheters in maternal and fetal blood vessels has been measured in conscious sows between 97 and 107 days of gestation. The maternofetal PD was -18 +/- 4 mV (mean +/- SE, n = 13, fetus negative) on the day of surgery and -29 +/- 5 mV (n = 6) on the day after surgery. Injection of 2, 20, or 200 micrograms of epinephrine into the fetuses caused a marked rapid change in maternofetal PD such that the fetus became less negative and, in some cases, became positive with respect to the mother. The maximum change, obtained with 20 micrograms, was 19.9 +/- 5.6 mV (n = 7); measurements of fetal plasma epinephrine concentrations (using high-performance liquid chromatography) after injection of this dose gave a time 0-extrapolated concentration of 436.5 +/- 169.0 nmol/l (n = 4). Injection of 20 micrograms of the beta-agonist isoprenaline caused a maximum change in PD of 20 +/- 4 mV (n = 6); 2 mg of the alpha-agonist phenylephrine was required to produce a similar change (15 +/- 2 mV, n = 6). Injection of the beta-antagonist propranolol (1 mg) reduced the effect of 20 micrograms epinephrine by 40%. The effect of catecholamine on maternofetal PD is similar in polarity and specificity to that found for transplacental PD in vitro in the same species. There is, however, a difference between resting maternofetal and transplacental PD that remains unexplained.

Animals↗
PubMed1988

Sex difference in fetal head growth.

Growth of the fetal biparietal diameter (BPD) throughout the second and third trimesters was measured in a prospective longitudinal study. Linear-cubic equations were fitted to the data of individual fetuses and from these equations mean growth curves were produced for males and females. The head growth trajectories of males and females were significantly different. The study illustrates why the practice of dating pregnancies by ultrasonic fetal BPD measurement at about 16 weeks gestation can lead to error.

Cephalometry↗
PubMed1986

Electrical activity and sodium transfer across in vitro pig placenta.

Electrical activity generated by pieces of pig placenta, taken from anesthetized animals and mounted in Ussing chambers, has been investigated. Ten minutes after the start of voltage clamping, potential difference (PD; fetal side positive, open circuit), short circuit current (SCC), and resistance were 5.9 +/- 0.4 (SE) mV, 8.6 +/- 0.5 microA X cm-2, and 720 +/- 45 omega X cm2, respectively (n = 50). Ouabain (10(-4) M) added to the fetal side caused a maximum decline in PD and SCC from the time of addition of -3.7 +/- 0.98 mV and -3.9 +/- 1.4 microA X cm-2 (n = 6); epinephrine (10(-5) M) added to the fetal side caused increases of +1.0 +/- 0.2 mV and +4.0 +/- 1.4 microA X cm-2, respectively (n = 14). Drug concentrations for 50% maximum response for the effect of a series of adrenergic agonists on SCC were (in M) isoproterenol 1.2 +/- 0.05 X 10(-8), norepinephrine 6.1 +/- 0.3 X 10(-8), epinephrine 2.4 +/- 0.1 X 10(-7), and phenylephrine 4.7 +/- 0.2 X 10(-5), suggesting the involvement of fetally oriented beta-adrenergic receptors. Fetal epinephrine (10(-5) M) also stimulated net Na+ flux (Jnet) toward the fetal side to an extent equal to its effect on SCC. In control experiments Jnet was small but was inhibited by fetal side ouabain (10(-4) M) to produce a maternally directed Jnet, significantly different to the SCC. Replacement of Na+ by choline reduced SCC markedly but did not abolish it. In the absence of Na+, epinephrine had no effect on SCC. These results suggest that active Na+ transfer is not completely responsible for the control electrical activity of pig placenta. Epinephrine, however, modulates SCC entirely by stimulating net Na+ transfer toward the fetal side.

Adrenergic Agonists↗
PubMed1985

In vitro permeability of the pig placenta in the last third of gestation.

The pig placenta is membranous throughout gestation and is suitable for investigation as a membrane system. The site of maternal-fetal exchange in vivo is used for permeability measurements in vitro and its surface area can be measured morphometrically. Fetal weight, placental weight, placental DNA content, placental macroscopic surface area, epithelio-chorial membrane area and thickness, and permeability in vitro to urea, tritiated water and sodium were measured in eight conceptuses aged between 79 and 111 days. These solutes were selected in order to facilitate comparison with data for sheep. Urea permeability per unit DNA increased throughout the last third of gestation although placental weight and DNA content ceased to increase before term.

Animals↗
PubMed1983

Relationship of fetal to placental size: the pig model.

Placental weight and macroscopic surface area are closely correlated with fetal weight throughout the second half of gestation in the pig. The limiting effect of placental size on fetal weight becomes more obvious as gestation advances. Fetal weight/placental weight ratio increases as placental weight decreases. Within individual litters, lightweight placentas have up to 150% more macroscopic surface area per unit placental weight.

Animals↗
PubMed1976

Fetal growth retardation in the second trimester.

Growth of the fetal head was assessed by serial ultrasonic measurements in a prospective study of a randomly selected group of 126 mothers. Three cases exhibiting second trimester fetal head growth retardation with varying degrees of catch-up growth before term are illustrated.

Female↗