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Biomedical subjects

R P Ford

Publications and source records attributed to R P Ford.

At least 19 recordsLinked to original sources
PubMed1997

Smoking during pregnancy measured by population cotinine testing.

AIM: To establish a baseline cross-sectional prevalence of maternal smoking, measured by antenatal serum cotinine testing, in a population of pregnant women. METHODS: Residual sera from first and second routine antenatal blood samples were collected anonymously over a six-month period for pregnancies within the Canterbury region. Cotinine levels were measured by an ELISA test with a result of > 14 ng/mL indicative of active smoking. Only pregnancies ending in a confirmed live birth were considered in smoking prevalence calculations. There was a total of 1948 eligible residual blood samples. RESULTS: Of the 414 residual blood samples available for the first two months of pregnancy, 146 (35.3%) were found to be positive for cotinine. Smoking prevalence decreased over pregnancy so that by the third trimester 225 (26.8%) of 838 samples were cotinine positive. Infants born from smoking mothers had significantly lower birth weights. CONCLUSIONS: In 1994, a third of women tested in early pregnancy and a quarter of women tested in late pregnancy were identified as being smokers. Repeated objective cross-sectional surveys will allow accurate assessment of the efficacy of smokefree interventions both before and during pregnancy.

Birth Weight↗
PubMed1997

Housing and sudden infant death syndrome. The New Zealand Cot Death Study Group.

AIMS: This paper examined factors relating to the infants' place of domicile to see whether they increased the risk of sudden infant death syndrome (SIDS) beyond social and environmental effects previously published. METHODS: A case control study was undertaken in New Zealand between the years 1987-90. From all sudden infant death syndrome diagnoses over this time, parents of 393 (81%) sudden infant death syndrome infants consented to participate and these derive the cases. Controls were ascertained by randomly sampling 1800 infants from all babies born over 78% of the country. Parents of 1592 (88%) control infants consented to participate in the study. RESULTS: The relative risk of sudden infant death for infants usually residing in houses rented from the government (State houses) was 1.73 (95% CI: 1.13, 2.66) times that of infants with parents owning their house, after adjusting for likely social, economic and environmental confounding factors. However, the type of housing, construction of housing, heating and age of housing was not associated with sudden infant death syndrome. Although house size, measured in terms of bedroom numbers, was similar for sudden infant death syndrome and control infants (chi 2 = 0.40, df = 2, p = 0.82), the number of people normally residing within these houses was different. Sudden infant death syndrome infants' houses were less likely to have two adults and more likely to have more children normally resident. Density calculations (derived by calculating the children and/or adult numbers divided by bedroom numbers) revealed a non significant increase in relative risk, suggesting that housing overcrowding was not associated with sudden infant death syndrome in New Zealand. CONCLUSIONS: Infants domiciled in State houses are more likely to experience sudden infant death syndrome. However, this increased relative risk for sudden infant death syndrome appears to have little to do with the house per se and, perhaps, more to do with socioeconomic characteristics.

Adult↗
PubMed1997

The effect of season-of-response to ISAAC questions about asthma, rhinitis and eczema in children.

BACKGROUND: To examine whether responses to questions about the lifetime prevalence and 12-month period prevalence of symptoms of asthma and allergies are affected by the season in which the questions are asked. METHODS: The international Study of Asthma and Allergies in Childhood (ISAAC) Phase One was undertaken in six New Zealand centres; in three centres the effect of season was studied. Over three school terms at least 3000 children were studied in each of two age groups per centre (6-7 years; 13-14 years), one-third in each term respectively. The ISAAC standardized written questionnaires were used to identify asthma, rhinitis and eczema symptoms. The written questionnaire in the younger age group was completed by the parent/guardian. The older age group self-completed the written questionnaire and also a video questionnaire about asthma symptoms. RESULTS: The total number of respondents was 21,437, approximately half in each age group. The season of responding had no effect on the level of response to eczema questions. For the written asthma questionnaire no season-of-response effect was present for 6-7 year olds; for 13-14 year olds there was a trend to a higher rate of positive responses by those responding in winter, but in only one question did this reach statistical significance. With the video questionnaire there was a similar trend for a higher rate of positive responses when questions were asked in winter, but this did not reach statistical significance. For rhinitis symptoms there was a statistically significant season-of-response effect in both age groups with two questions; the fewest positive responses by the winter responders. CONCLUSIONS: There was no significant effect of season-of-response to questions on eczema symptoms, and most questions on asthma symptoms. There was a season-of-response effect on responses to questions on rhinitis symptoms suggesting a recall bias relating to recency of symptoms.

Adolescent↗
PubMed1997

The febrile stress of routine vaccination does not increase central apnoea in normal infants.

We tested the hypothesis that the febrile stress of routine vaccination would increase central apnoea in normal infants. Twenty-one normal infants had continuous overnight breathing and temperature recorded at home, before and after 58 routine vaccination episodes. Central apnoea, of at least 5 sec duration, was detected by computer algorithm and confirmed by human inspection. The longest recorded apnoea was 16 sec (n = 1) during 3629 h of sleep. Overnight rectal temperature increased after vaccination (median 0.52 degrees C, 95% CI 0.40, 0.65). Apnoea density reduced on 46/53 vaccination nights (median -29%, 95% CI -20, -37) followed by an increase on subsequent nights (median +10%, 95% CI +1%,+21%). Overall, apnoea density was similar during the 3 nights preceding and 4 nights following vaccination (median +1%, 95% CI +9,-6). The febrile stress of routine vaccination did not increase central apnoea in normal infants.

Body Temperature↗
PubMed1997

Influences on breastfeeding in southeast England.

Factors associated with not exclusively breastfeeding at discharge from the obstetric hospital and with duration of breastfeeding were examined in 700 randomly sampled infants. Obstetric records were examined in 97.7% of the subjects and 73.0% of subject families were interviewed. There were 444 (66.5%) infants exclusively breastfed at discharge from the obstetric hospital. Factors associated with not exclusively breastfeeding at discharge from the obstetric hospital after adjusting for potential confounders were: mother leaving school aged less than 18 years, mother not attending antenatal classes and the use of a dummy in the 2 weeks before the interview. Bed sharing practice in the 2 weeks before the interview was associated with exclusively breastfeeding at discharge from the obstetric hospital. Factors associated with a shorter duration of breastfeeding were: mother leaving school before 18 years of age, smoking 20 or more cigarettes per day and use of a dummy. Dummy use may causally reduce breastfeeding or might be a marker for breastfeeding difficulties. There was a dose-response relationship with smoking, with heavier smokers breastfeeding for the shortest time periods. Bed sharing was associated with a longer duration of breastfeeding. This may not necessarily be a causal relationship because breastfeeding may promote bed sharing. The effect of dummy use and bed sharing on breastfeeding warrants further study.

Adult↗
PubMed1997

SIDS, illness, and acute medical care. New Zealand Cot Death Study Group.

One component of the Back to Sleep campaign to reduce the risk of sudden infant death syndrome (SIDS) is the recommendation that parents seek medical attention if their infant is unwell. The aim of this study was to investigate of SIDS could in part be explained by sick infants not getting appropriate medical care. Data on symptoms of illness and on acute medical contacts made for infants dying from SIDS (n = 390) within two weeks of their death were compared with those from a randomly selected group of control infants (n = 1592). SIDS cases had more severe illness than controls (odds ratio (OR) = 3.43; 95% confidence interval (CI) = 1.69 to 5.38), and were more likely to have seen a general practitioner (OR = 1.37; 95% CI = 1.09 to 1.73) or attended hospital (OR = 3.43, 95% CI = 1.09 to 1.73). Only 1.3% of all SIDS cases had symptoms suggesting severe illness and had not seen a general practitioner. A lack of medical contacts in the two weeks before death does not contribute to the risk of SIDS.

Acute Disease↗
PubMed1997

Smoking during pregnancy: how reliable are maternal self reports in New Zealand?

OBJECTIVE: To determine the reliability of self reports of smoking during pregnancy. METHODS: Residual sera from early and late antenatal blood samples were tested for cotinine for all pregnancies over a six month period. Over an overlapping 12 month period, a postal questionnaire on smoking was also sent to all new mothers (n = 4857) when their baby was 4-8 weeks old. Smoking status from obstetric booking notes was also obtained. RESULTS: The cotinine-validated smoking prevalence was 31.3% for the first trimester and 27.7% for the third trimester. Questionnaire self reported prevalences were 19.2% and 15.7% for the first and third trimesters respectively, and 18.9% for obstetric booking. Of cotinine-validated smokers, 22% denied smoking-self deceivers. Of mothers who replied to the questionnaire, a half appeared to systematically under report the amount they smoked. CONCLUSIONS: Nearly a quarter of smoking pregnant women did not report smoking. Moreover, of those who did, the amount smoked was often under reported. This tendency to under report may rise as pressures to stop smoking increase. Accurate measures of smoking prevalence in pregnant women will require objective testing.

Cotinine↗
PubMed1997

Risk factors for sudden infant death syndrome following the prevention campaign in New Zealand: a prospective study.

OBJECTIVES: To identify the risk factors for sudden infant death syndrome (SIDS) following a national campaign to prevent SIDS. METHODS: For 2 years (October 1, 1991 through September 30, 1993) data were collected by community child health nurses on all infants born in New Zealand at initial contact and at 2 months. RESULTS: There were 232 SIDS cases in the postneonatal age group (2.0/1000 live births) and these were compared with 1200 randomly selected control subjects. Information was available for 127 cases (54.7%) and 922 (76.8%) of controls. The previously identified modifiable risk factors were examined. The prevalence of prone sleeping position of the infant was very low (0.7% at initial contact and 3. 0% at 2 months), but was still associated with an increased risk of SIDS. In addition, the side sleeping position was also found to have an increased risk of SIDS compared with the supine sleeping position (at 2 months: adjusted odds ratio (OR) = 6.57; 95% confidence interval (CI) = 1.71, 25.23). Maternal smoking was found to be the major risk factor for SIDS. Bed sharing was also associated with an increased risk of SIDS. There was an interaction between maternal smoking and bed sharing on the risk of SIDS. Compared with infants not exposed to either bed sharing or maternal smoking, the adjusted OR for infants of mothers who smoked was 5.01 (95% CI = 2.01, 12.46) for bed sharing at the initial contact and 5.02 (95% CI = 1.05, 24. 05) for bed sharing at 2 months. In this study breastfeeding was not associated with a statistically significant reduction in the risk of SIDS. The other risk factors for SIDS identified were: unmarried mother, leaving school at a younger age, young mother, greater number of previous pregnancies, late attendance for antenatal care, smoking in pregnancy, male infant, Maori ethnicity, low birth weight, and shorter gestation. CONCLUSIONS: After adjustment for potential confounders, prone and side sleeping positions, maternal smoking, and the joint exposure to bed sharing and maternal smoking were associated with statistically significant increased risk of SIDS. A change from the side to the supine sleeping position could result in a substantial reduction in SIDS. Maternal smoking is common in New Zealand and with the reduction in the prevalence of prone sleeping position is now the major risk factor in this country. However, smoking behavior has been difficult to change. Bed sharing is also a major factor but appears only to be a risk to infants of mothers who smoke. Addressing bed sharing among mothers who smoke could reduce SIDS by at least one third. Breastfeeding did not appear to offer a statistically significant reduction in SIDS risk after adjustment of potential confounders, but as breastfeeding rates are comparatively good in New Zealand, this result should be interpreted with caution as the power of this study to detect a benefit is small.

Beds↗
PubMed1996

Breastfeeding in Canterbury over three decades.

AIM: To document breastfeeding levels in Canterbury between 1968 to 1994. METHODS: The method of feeding at discharge from hospital, at 4 weeks and at 3 months of age was obtained from maternal obstetric records, Plunket nursing notes, parent interviews or by self completed questionnaires. Data were compiled for the years 1968 to 1994. RESULTS: In 1968, only half of all mothers were breastfeeding when discharged. However, rates have steadily increased since then so that by 1990, 90% of infants were recorded as being breastfed at discharge. Levels of exclusive breastfeeding have also increased. By 1992-4, 82.2% of babies were being exclusively breastfed at discharge from hospital, 72.4% at 4 weeks and 62.5% at 3 months. CONCLUSION: Levels of breastfeeding in Canterbury are now relatively high. The Public Health Commission has set a target for 75% of infants to be fully breastfed at 3 months of age by the year 2000. To achieve this the circumstances that hinder breastfeeding need to be addressed.

Bottle Feeding↗
PubMed1996

Prevalence of smoking in early pregnancy by census area: measured by anonymous cotinine testing of residual antenatal blood samples.

AIM: To accurately measure the prevalence of smoking in early pregnancy by census area units (CAU) in Christchurch. METHODS: Smoking status in pregnancy was determined by serum cotinine assay for all antenatal blood samples taken over a 6 month period. CAUs in Christchurch were grouped into quartiles according to the proportion of maternal smokers. Social factors from 1991 census data were used to describe the characteristics of each quartile. RESULTS: The overall rate of smoking in pregnancy was 33.0%. Rates ranged from 10.6% to 56.9% for the census area groups. CAUs in the upper quartile (39-57% of women smoking in pregnancy) were clustered together geographically and were associated with lower socioeconomic indices. The strongest correlation was between average income with smoking rates (Pearson correlation coefficient 0.76). CONCLUSION: Smoking rates in pregnancy have remained at around 30% for at least 20 years, with some areas of the city having rates nearly double this. It would seem logical to promote smoke-free pregnancy activities in localities with the highest rates of smoking. Future evaluation of the efficacy of such programmes should be done using objective measurements.

Confidence Intervals↗
PubMed1996

Infant room-sharing and prone sleep position in sudden infant death syndrome. New Zealand Cot Death Study Group.

BACKGROUND: There is evidence that the risk of sudden infant death syndrome is lower among ethnic groups in which parents generally share a room with the infant for sleeping. We investigated whether the presence of other family members in the infant's sleeping room affects the risk of the sudden infant death syndrome. METHODS: The case-control study covered a region with 78% of all births in New Zealand during 1987-90. Home interviews were completed with parents of 393 (81.0% of total) babies who died from the sudden infant death syndrome aged 28 days to 1 year and 1592 (88.4% of total) controls, selected from all hospital births in the study region. FINDINGS: The relative risk of sudden infant death for sharing the room with one or more adults compared with not sharing was 0.19 (95% CI 0.08-0.45) for sharing at night during the last 2 weeks and 0.27 (0.17-0.41) for sharing in the last sleep, after control for other confounders. Sharing the room with one or more children did not affect the relative risk (1.25 [0.86-1.82] for sharing during last 2 weeks; 1.29 [0.85-1.94] for sharing in last sleep). There was a significant interaction (p = 0.033) between not sharing the room with an adult and prone sleep position in the last sleep. Compared with infants sharing the room with an adult and not prone, the multivariate relative risk was 16.99 (10.43-27.69) for infants not sharing with an adult and prone, 3.28 (2.06-5.23) for infants sharing the room and prone, and 2.60 (1.58-4.30) for infants not sharing the room and not prone. The interaction between adult room-sharing and prone sleep position suggests that both exposures may affect the risk of sudden infant death syndrome through a common mechanism. INTERPRETATION: We recommend that infants sleep in the same bedroom as their parents at night to reduce the risk of sudden infant death syndrome.

Adult↗
PubMed1996

An enzyme-linked immunosorbent assay (ELISA) for the measurement of activated factor XII (Hageman factor) in human plasma.

A direct enzyme-linked immunosorbent assay (ELISA) employing 2/215 mouse monoclonal hybridoma antibody is described. The assay is capable of detecting activated factor XII in human plasma and can be used to assess early detection of the intrinsic blood coagulation pathway. No cross reactivity with human factor XII zymogen has been found. The assay was used to assess activation of factor XII in patients with renal failure, pregnancy and diabetes compared to a control group.

Antibodies, Monoclonal↗
PubMed1996

Symptoms, sweating and reactivity of infants who die of SIDS compared with community controls. New Zealand National Cot Death Study Group.

OBJECTIVE: To describe the symptoms of illness reported by the parents of infants who have died of sudden infant death syndrome (SIDS) compared with those reported by community controls. METHODOLOGY: A nationwide case-control study involving regions of New Zealand with 78% of all births between 1987 and 1990. Home interviews were completed with parents of 393 (81% of total) infants who died from SIDS in the post neonatal age group, and 1592 (88.4% of total) controls who were a representative sample of all hospital births in the study region. RESULTS: Symptoms of infection were common in both cases and controls, but were not significantly different. Infants dying of SIDS, however, were likely to have symptoms suggestive of more severe illness in the 2 days before death (odds ratio [OR] = 3.02, 95% confidence interval [CI] 1.69-5.38). After adjusting for potential confounding this was still statistically significant (adjusted OR 2.36, 95% Cl 1.14-4.90). Also, babies dying of SIDS were more likely to have been less reactive to their environment in the 2 weeks before death compared with the controls (univariate OR 0.88, 95% Cl 0.55- 1.39, adjusted OR 0.55, 95% CI 0.29-0.88). 'Drenching' sweats at least weekly were reported for 15.6% of case infants compared with 5.9% of control infants (adjusted OR 2.12, 95% CI 1.53-3.39). Forty per cent of these infants had this symptom in the first 4 weeks of life when it was also associated with a significantly raised risk of SIDS. Apnoea lasting more than 20 s was reported for 13.2% of case infants compared with 5.3% of control infants (adjusted OR 1.93, 95% CI 1.17-3.17). Similarly, 71.8% of case infants' faces were reported to never turn red while awake compared to 49.8% of control infants (adjusted OR 2.98, 95% CI 2.19-4.07). CONCLUSIONS: Only a small number (6.4%) of babies who die of SIDS have symptoms of serious illness in the 2 days before death. There is support for the hypothesis that there is a group of babies dying of SIDS who have subtle abnormalities in autonomic control or arousal ability.

Apnea↗
PubMed1996

Life events, social support and the risk of sudden infant death syndrome.

The effects of a lack of maternal social support and stressful life events on the risk of Sudden Infant Death Syndrome (SIDS) were examined by case-control design: 390 cases and 1592 control infants. A seven item index of mother's social support was used. A possible 21 life events experienced by each family were summed and then put into one of three categories: 0-2, 3-5, and 6 or more life events. Similar levels of maternal social support were found for both groups. SIDS families experienced significantly more stressful life events than control families, but once social factors had been taken into account this association was lost.

Analysis of Variance↗
PubMed1996

Breathing, sleep state, and rectal temperature oscillations.

Overheating may cause terminal apnoea and cot death. Rectal temperature and breathing patterns were examined in normal infants at home during the first 6 months of life. Twenty one infants had continuous overnight rectal temperature and breathing recordings for 429 nights (mean 20.4 nights, range 7-30) spaced over the first six months of life. Periods when breathing was 'regular' were directly marked on single night records. Sleep state was determined from respiratory variables. 'Regular' breathing was a reliable marker of 'quiet' sleep (specificity 93%). The duration of 'quiet' sleep increased from 6 to 22 minutes from two weeks to three months of age and then remained static, as did the proportion of sleep spent in the quiet phase (9% to 34%). Rectal temperature fell during 66% of quiet sleep and usually rose during rapid eye movement (REM) sleep. The drop in rectal temperature was maximal at the start of quiet sleep, whereas the maximum rise during REM sleep was reached after 10 to 15 minutes. Oscillations in rectal temperature are associated with changes in sleep and breathing state. The maturation of rectal temperature patterns during the first six months of life are closely related to a maturation of sleep state and breathing patterns.

Aging↗
PubMed1996

Allergy and the risk of sudden infant death syndrome. The Members of the New Zealand Cot Death Study Group.

BACKGROUND AND OBJECTIVE: There are several sources that suggest that there is a link between allergy and sudden infant death syndrome. We endevavoured to look for evidence of an association between allergic disease and the risk of sudden infant death syndrome (SIDS). METHODS: A nationwide case-control study covering a region with 78% of all births in New Zealand during 1987-90. Interviews were completed with the parents of 393 (81.0% of total) infants who died from the sudden infant death syndrome (SIDS), and 1592 (88.4% of total) control families who were a representative sample of all hospital births in the study region. RESULTS: Eczema was reported in 13.9% control infants compared with only 8.0% of the SIDS infants, univariate odds ratio for this in terms of risk for SIDS was 0.56 (95% confidence interval 0.37, 0.84) for infants with eczema compared with those without. This lesser risk for SIDS was unchanged when adjusted for potential confounding factors. The risk of SIDS was not associated with reported cow's milk reactions or a family history of allergic symptoms once adjustments were made for possible confounding factors. CONCLUSION: Infants with skin disorders identified by their parents as eczema had a low risk for SIDS. Families can be reassured that atopy is not a risk factor for SIDS.

Asthma↗
PubMed1995

The length of the referral chain after failing preschool tympanometry.

AIMS: To describe the time intervals during the process of detection and management of chronic secretory otitis media/glue ear. METHOD: Tympanometry records of 508 preschool children who failed both tympanometry screening and the subsequent retest were examined. Additional information was obtained from 205 parents/caregivers by telephone interview. RESULTS: Calculations of time intervals between tympanometry screening and retesting showed that 75% of children had been retested within 20 weeks and 95% by 40 weeks. Two-thirds (67%) of children had visited their general practitioner within 4 weeks of failing their retest, although 13% had still yet to be seen by 20 weeks. The mean time interval between the initial general practitioner visit and subsequently being seen by an ENT specialist was 20 weeks in the public system compared to 5 weeks if seen privately (p < 0.001). CONCLUSION: The preschool tympanometry screening programme functioned well, although there were delays in retesting 25% of preschoolers. There were substantial time intervals for some children for each link in the referral chain. The reasons for these delays needs investigation to determine how much it is a part of the treatment process and how much due to waiting list problems.

Acoustic Impedance Tests↗